Vintage Simmons Drums (UK) Users Group

Hi,
After much procrastinating I opened up the brain, looking for obvious signs as to why the Hi-Tom isn't working & can't see anything -no fried components etc. Spent an evening trying to follow the circuitry using a bright light, magnifying glass & schematic but nothing obvious.
So not sure what to do now. My electronics isn't up to diagnosing this kind of stuff. Is there anyone on the UK who does synth repairs or a related business?

Also, just putting it back together and found that the schematic I'm following doesn't show (or I can't find - entirely probable) the connections to the power switch. I nearly took a photo but thought "it'll be on the schematic". Oops. There are 4 pins, 11, 12, 24 & 25 and the mains supply, blue & brown then orange & black going to the transformer. Can anyone tell me which way round they go. Many thanks.

Any help would be greatly appreciated as I've just started on fills in my drumming lessons & it's unsatisfactory doing them with a dead tom.
Cheers
Jonathan

I have no specs etc, but James Walker at Synthrestore (I think that's
the name) is a good guy. Not sure how he's when it comes to prices but
try thee mighty search engine of your choice to find him...

--
electronically yours, jesper

- -- --- ---- ----- ---- --- -- -
www.electronic-obsession.se


Jonathan skrev 2012-06-26 23:09:

> Hi,
> After much procrastinating I opened up the brain, looking for obvious
> signs as to why the Hi-Tom isn't working & can't see anything -no fried
> components etc. Spent an evening trying to follow the circuitry using a
> bright light, magnifying glass & schematic but nothing obvious.
> So not sure what to do now. My electronics isn't up to diagnosing this
> kind of stuff. Is there anyone on the UK who does synth repairs or a
> related business?
>
> Also, just putting it back together and found that the schematic I'm
> following doesn't show (or I can't find - entirely probable) the
> connections to the power switch. I nearly took a photo but thought
> "it'll be on the schematic". Oops. There are 4 pins, 11, 12, 24 & 25 and
> the mains supply, blue & brown then orange & black going to the
> transformer. Can anyone tell me which way round they go. Many thanks.
>
> Any help would be greatly appreciated as I've just started on fills in
> my drumming lessons & it's unsatisfactory doing them with a dead tom.
> Cheers
> Jonathan

Jesper,
Thanks, I've now emailed Synthrestore as other ppl have recommended them as well.

I'll wait for the price (ow). Will post any helpful developments.
Cheers
J

--- In Simmons_Drums@yahoogroups.com, jesper <jesper@...> wrote:
>
> I have no specs etc, but James Walker at Synthrestore (I think that's
> the name) is a good guy. Not sure how he's when it comes to prices but
> try thee mighty search engine of your choice to find him...
>
> --
> electronically yours, jesper
>
> - -- --- ---- ----- ---- --- -- -
> www.electronic-obsession.se
>
>
> Jonathan skrev 2012-06-26 23:09:
> > Hi,
> > After much procrastinating I opened up the brain, looking for obvious
> > signs as to why the Hi-Tom isn't working & can't see anything -no fried
> > components etc. Spent an evening trying to follow the circuitry using a
> > bright light, magnifying glass & schematic but nothing obvious.
> > So not sure what to do now. My electronics isn't up to diagnosing this
> > kind of stuff. Is there anyone on the UK who does synth repairs or a
> > related business?
> >
> > Also, just putting it back together and found that the schematic I'm
> > following doesn't show (or I can't find - entirely probable) the
> > connections to the power switch. I nearly took a photo but thought
> > "it'll be on the schematic". Oops. There are 4 pins, 11, 12, 24 & 25 and
> > the mains supply, blue & brown then orange & black going to the
> > transformer. Can anyone tell me which way round they go. Many thanks.
> >
> > Any help would be greatly appreciated as I've just started on fills in
> > my drumming lessons & it's unsatisfactory doing them with a dead tom.
> > Cheers
> > Jonathan
>

Planning ahead here - early indications are that I won't be able to get my SDS 9 restored for some while (just had a quote from Synthrestore and it coincides with over £2k bill for work on my car, so timing not good...)& it would then be gone for a while.

Probably heresy, but I was contemplating buying a cheap other brain so that me & a Small Person could keep practising and then have as a backup. I could probably slip ca £50 through the budget, seeing as we're paying for drumming lessons. A quick ebay scan has thrown up an Alesis DM5. A trawl through the posts here suggest that my SDS9 pads will trigger this OK? Or is this likely to be just as temperamental?

Can anyone advise on a suitable cheap backup till I can get the SDS sorted?

Many thanks
Jonathan

PS
Anyone had any experience of Antech Systems (http://www.antech-systems.com/) in Hailsham? Not too far from me & I could deliver personally rather than post.

I can confirm your pads will trigger a DM5. Sorry I can't help with
anything else, and bad luck with the car.


[Non-text portions of this message have been removed]

Some people actually prefer the D4 over the DM5, which is cool because
they're a little less expensive. Either one should work fine though.
They're made to do everything ok, but don't stand out as being excellent
in any one area.

I see the low-end Roland V-Drum brains (TD3 for example) selling for about
the same price, too. Those sound punchier imho, but they're less
programmable /flexible than the Alesis units.

If you don't like the sounds of the Alesis, you can just use it as a
trigger-to-MIDI convertor, and add something more
punchy/deeper/professional like an old Roland R8M. The prices on all these
are pretty level right now, so when your SDS9 is back you can very likely
sell it all off for what you paid for it :-)


all my best,
- Scott

it is really sad that i find that in a world that they say every thing recycleable and going green cheap products are being built that only last a year until warrantry is over and products are thrown out because it is cheaper to buy a new one than have it fixed,so any one with the knowledge to fix simmons drums are practically non exsistant not to mention trying to get a hold of schematics'.its a shame to see schematic boards being parted out,ie sds 7 ect.four modules down that are basically paper weights.............sad

[Non-text portions of this message have been removed]

ill try and get time to take my sds9 apart and send pictures to you as busy as i am ,im in the same situation with my mtms,sds 1,mtx 9 and it is vary frusterating

[Non-text portions of this message have been removed]

in my learning  of electronics if all other toms are workingfine i doubt it is the transformer,if capasiters blow they will become convex instead of being flat.diodes can be tested using a metre,special setting see manual on metre ics look up number on top of ic and see inputs and out puts for voltage.the other toms should pretty much be the same as the high tom so compare voltages from medium tom to high..if any thing the first place i would look at is the pots,volume and sensitivity as they get dusty ect ,create unwanted sounds when adjusting

[Non-text portions of this message have been removed]

Open the unit up and look for IC65 (A CD4051). The small dot on the IC is next to pin 1 on the IC so count along the IC from there and then back up the otherside till you get to pin 12. Apply a 5v carefully and quickly on then off. If the Hitom triggers the soundside of the unit is ok. IC65 provides the trigger pulses to the various voices so if the unit works when you do as I suggested, you need to start by replacing IC65. If all other functions of the SDS9 are working, this should fix the problem.

Let me know how you go

--- In Simmons_Drums@yahoogroups.com, "Jonathan" <capnfishy@...> wrote:
>
> Hi,
> After much procrastinating I opened up the brain, looking for obvious signs as to why the Hi-Tom isn't working & can't see anything -no fried components etc. Spent an evening trying to follow the circuitry using a bright light, magnifying glass & schematic but nothing obvious.
> So not sure what to do now. My electronics isn't up to diagnosing this kind of stuff. Is there anyone on the UK who does synth repairs or a related business?
>
> Also, just putting it back together and found that the schematic I'm following doesn't show (or I can't find - entirely probable) the connections to the power switch. I nearly took a photo but thought "it'll be on the schematic". Oops. There are 4 pins, 11, 12, 24 & 25 and the mains supply, blue & brown then orange & black going to the transformer. Can anyone tell me which way round they go. Many thanks.
>
> Any help would be greatly appreciated as I've just started on fills in my drumming lessons & it's unsatisfactory doing them with a dead tom.
> Cheers
> Jonathan
>

Hello,

servicing the SDS9 can be a horrible thing. I "repaired" several units by simply changing the software 6.0 or 5.0 back to 3.0. The explanation of this MAY be, that when the s/h capacitors age, they can't react to the "fast" scanning of software as 5.0 or higher. Or anybody has another idea why? Doesn't matter, the result counts :-)

Stories like this I can tell a lot. I hate to check SDS9's. People complain about parameters not being able to adjust or one trigger missing. In ALL cases one or some of the demuxer ICs (4051) are dead. They don't deliver the right data or trigger to the sound producing units. I always replace all at once, for me as a slightly experienced service person, this takes A DAY. It is very little space on the SDS9s PCB, meaning, that you can destroy a lot if you don't pay attention.

If someone is buing these old devices, he has to remember, that the components are aging, not only the capacitors. And if you fixed one thing today, tomorrow another thing might break. These old beasts are not reliable and I would never recommend to take them to stage. So frustration helps nobody, think of an old car like an MG. You spend much more time mending something than driving, and this is ok.

There are many people out there "shooting" an SDS9 at EBAY and later complaining, that nobody knows how to repair it. I know how to do it (this costs money) and I supply anybody with Thierry EPPHERREs worldwide best schematics (this is free).

SDS9: It is not plug and PLAY, it's plug and PRAY.

Good luck

Michael

----- Original Message -----
From: Brian Horton
To: Simmons_Drums@yahoogroups.com
Sent: Friday, July 20, 2012 7:23 AM
Subject: [Simmons Drums] Re: SDS 9 elementary problem & deeper fault



in my learning of electronics if all other toms are workingfine i doubt it is the transformer,if capasiters blow they will become convex instead of being flat.diodes can be tested using a metre,special setting see manual on metre ics look up number on top of ic and see inputs and out puts for voltage.the other toms should pretty much be the same as the high tom so compare voltages from medium tom to high..if any thing the first place i would look at is the pots,volume and sensitivity as they get dusty ect ,create unwanted sounds when adjusting

[Non-text portions of this message have been removed]





[Non-text portions of this message have been removed]

I fully agree with Michael's comments. There are people who can repair this gear but it is very time consuming and ultimately costs money. I have repaired many Simmons units and most of the faults are due to age or sadly with some units, poor build quality. This is not a poor reflection of simmons themselves. Most of the units were heavily hand built, built during a time where demand outstripped the ability to supply etc. Like an old car, don't buy one expecting to get years of trouble free use. These bits of old kit need regular TLC to keep them running. If you can't afford to do this or don't have the knowledge to do it yourself, vintage music gear is not for you. If you intend to hit the road and gig with them, expect things will go wrong. For gigging an old unit, you really need to go over any old gear resoldering all joints, replacing electrolytic capacitors, tightening screws, cleaning plugs etc. Yes there are people who will help keep it all going and many have spent lots of hours redrawing schematics etc. I myself have been slowly redrawing PCB's etc so at some point in the future new boards "could" be produced to keep the gear running. The SDS9 was a kick arse design that used a close connection between hardware and software to produce it's sounds, eproms for samples, curtis chips for analogue and the cpu itself generates the bassdrum waveshape in realtime. So it makes sense things will and do go wrong with them.

Michael Buchner skrev 2012-07-20 19:53:

> SDS9: It is not plug and PLAY, it's plug and PRAY.

Wise words Michael - this is the same for most old machines though some
are messier than others.

--
electronically yours, jesper

- -- --- ---- ----- ---- --- -- -
www.electronic-obsession.se

what i was trying to say is that all the electronic engineers that can repair simmons equipment are like jedi knights and will be no longer because electronics is changing so fast its cheaper to buy new than fix the old ,where one cant afford a living fixing electronics,i see it in my city. But saddly the old is the best quality and for simmons sound

[Non-text portions of this message have been removed]

Michael is one of the electronic engineers that i found  has been the most helpfull with all the questions i have asked  wished he resided in canada

[Non-text portions of this message have been removed]

It may be a hard fact to accept and I don't write this to irritate, but
as someone mentioned in another forum or list: With neither cash nor
ability to fix something - better stick with new gear.
I'm fortunate enough to have had patience to learn basic electronics to
solve smaller problems myself. When out of skills and/or knowledge I
have a good friend who loves digging into old gear.
I'm not saying the SDS-9 isn't a pain to repair, many digital things
are. But if you plan on a life with ancient electronic instruments you
have the mentioned choices, pay someone or do it yourself 'cause the
gear won't survive forever.
BTW - I think many of us europeans prefer if Michael stays here! ;)

--
electronically yours, jesper

- -- --- ---- ----- ---- --- -- -
www.electronic-obsession.se


Brian Horton skrev 2012-07-24 06:56:

> what i was trying to say is that all the electronic engineers that can
> repair simmons equipment are like jedi knights and will be no longer
> because electronics is changing so fast its cheaper to buy new than fix
> the old ,where one cant afford a living fixing electronics,i see it in
> my city. But saddly the old is the best quality and for simmons sound

*like*

--- In Simmons_Drums@yahoogroups.com, Brian Horton <brianhorton21@...> wrote:
>
> Michael is one of the electronic engineers that i found  has been the most helpfull with all the questions i have asked  wished he resided in canada
>
> [Non-text portions of this message have been removed]
>

I am able to put some money to getting this sorted (I had some money earmarked to get my Jen SX1000 resurrected, but that will have to wait) - it's going off to a local electronic instrument repairer tomorrow.
Armed with some of the nuggets of wisdom you've all helped me with may help to keep the bill down a bit. Maybe it'll be a write off, which would be a pity, and then I would have to go down the acoustic route, as the drumming is the main thing, although I enjoy analogue synthesisers, but its a fact - if you can't fix it or afford to get it fixed then there has to be a parting of ways.
Thanks for all the help I've had. Will update.
Jonathan.

--- In Simmons_Drums@yahoogroups.com, jesper <jesper@...> wrote:
>
> It may be a hard fact to accept and I don't write this to irritate, but
> as someone mentioned in another forum or list: With neither cash nor
> ability to fix something - better stick with new gear.
> I'm fortunate enough to have had patience to learn basic electronics to
> solve smaller problems myself. When out of skills and/or knowledge I
> have a good friend who loves digging into old gear.
> I'm not saying the SDS-9 isn't a pain to repair, many digital things
> are. But if you plan on a life with ancient electronic instruments you
> have the mentioned choices, pay someone or do it yourself 'cause the
> gear won't survive forever.
> BTW - I think many of us europeans prefer if Michael stays here! ;)
>
> --
> electronically yours, jesper
>
> - -- --- ---- ----- ---- --- -- -
> www.electronic-obsession.se
>
>
> Brian Horton skrev 2012-07-24 06:56:
> > what i was trying to say is that all the electronic engineers that can
> > repair simmons equipment are like jedi knights and will be no longer
> > because electronics is changing so fast its cheaper to buy new than fix
> > the old ,where one cant afford a living fixing electronics,i see it in
> > my city. But saddly the old is the best quality and for simmons sound
>

Richard,
Thanks for that - I gather this is a bit of a pig to work on so it's going in to a chap tomorrow - hopefully your info will be of use in the diagnostic process.
Regards
Jonathan

--- In Simmons_Drums@yahoogroups.com, "Richard" <warlandr63@...> wrote:
>
> Open the unit up and look for IC65 (A CD4051). The small dot on the IC is next to pin 1 on the IC so count along the IC from there and then back up the otherside till you get to pin 12. Apply a 5v carefully and quickly on then off. If the Hitom triggers the soundside of the unit is ok. IC65 provides the trigger pulses to the various voices so if the unit works when you do as I suggested, you need to start by replacing IC65. If all other functions of the SDS9 are working, this should fix the problem.
>
> Let me know how you go
>
> --- In Simmons_Drums@yahoogroups.com, "Jonathan" <capnfishy@> wrote:
> >
> > Hi,
> > After much procrastinating I opened up the brain, looking for obvious signs as to why the Hi-Tom isn't working & can't see anything -no fried components etc. Spent an evening trying to follow the circuitry using a bright light, magnifying glass & schematic but nothing obvious.
> > So not sure what to do now. My electronics isn't up to diagnosing this kind of stuff. Is there anyone on the UK who does synth repairs or a related business?
> >
> > Also, just putting it back together and found that the schematic I'm following doesn't show (or I can't find - entirely probable) the connections to the power switch. I nearly took a photo but thought "it'll be on the schematic". Oops. There are 4 pins, 11, 12, 24 & 25 and the mains supply, blue & brown then orange & black going to the transformer. Can anyone tell me which way round they go. Many thanks.
> >
> > Any help would be greatly appreciated as I've just started on fills in my drumming lessons & it's unsatisfactory doing them with a dead tom.
> > Cheers
> > Jonathan
> >
>

Hello,

I can attest to Michael's statements that these can be a real pain when not working. He has been a big help to me lately with one of these SDS9 units as well. After having replaced all the caps on the board, not just the demux ones, I am back to square one as well. My next step is IC replacement, and hopefully it gets mine working again soon. Only time will tell. The analogy of working on an old MG is rather appropriate here, and having owned several of those in the past, I know exactly of what he speaks. LOL!

~Paul

--- In Simmons_Drums@yahoogroups.com, "Michael Buchner" <buchnerelectronics@...> wrote:
>
> Hello,
>
> servicing the SDS9 can be a horrible thing. I "repaired" several units by simply changing the software 6.0 or 5.0 back to 3.0. The explanation of this MAY be, that when the s/h capacitors age, they can't react to the "fast" scanning of software as 5.0 or higher. Or anybody has another idea why? Doesn't matter, the result counts :-)
>
> Stories like this I can tell a lot. I hate to check SDS9's. People complain about parameters not being able to adjust or one trigger missing. In ALL cases one or some of the demuxer ICs (4051) are dead. They don't deliver the right data or trigger to the sound producing units. I always replace all at once, for me as a slightly experienced service person, this takes A DAY. It is very little space on the SDS9s PCB, meaning, that you can destroy a lot if you don't pay attention.
>
> If someone is buing these old devices, he has to remember, that the components are aging, not only the capacitors. And if you fixed one thing today, tomorrow another thing might break. These old beasts are not reliable and I would never recommend to take them to stage. So frustration helps nobody, think of an old car like an MG. You spend much more time mending something than driving, and this is ok.
>
> There are many people out there "shooting" an SDS9 at EBAY and later complaining, that nobody knows how to repair it. I know how to do it (this costs money) and I supply anybody with Thierry EPPHERREs worldwide best schematics (this is free).
>
> SDS9: It is not plug and PLAY, it's plug and PRAY.
>
> Good luck
>
> Michael
>
>
> ----- Original Message -----
> From: Brian Horton
> To: Simmons_Drums@yahoogroups.com
> Sent: Friday, July 20, 2012 7:23 AM
> Subject: [Simmons Drums] Re: SDS 9 elementary problem & deeper fault
>
>
>
> in my learning of electronics if all other toms are workingfine i doubt it is the transformer,if capasiters blow they will become convex instead of being flat.diodes can be tested using a metre,special setting see manual on metre ics look up number on top of ic and see inputs and out puts for voltage.the other toms should pretty much be the same as the high tom so compare voltages from medium tom to high..if any thing the first place i would look at is the pots,volume and sensitivity as they get dusty ect ,create unwanted sounds when adjusting
>
> [Non-text portions of this message have been removed]
>
>
>
>
>
> [Non-text portions of this message have been removed]
>

On 19 May 2013 at 13:20 simmonssds7fan <ptmetcalf@...> wrote:

> Hello,
>
> The analogy of working on an old MG is rather appropriate here, and having
> owned several of those in the past, I know exactly of what he speaks. LOL!
>
> ~Paul
>

At least an MG is easy to work on - by the sounds of it the SDS-9 is more like
working on a Jaguar E-Type.

Chris
(former MGB-GT owner)

I totally get the analogy, but I'm with Chris - as an ex MG owner myself, they're not so bad to work on though and I would have thought the crammed-in effect and temperamental nature was more apt with an E-Type or primadonna Ferrari...
J

--- In Simmons_Drums@yahoogroups.com, "chris@..." <chris@...> wrote:
>
>
>
> On 19 May 2013 at 13:20 simmonssds7fan <ptmetcalf@...> wrote:
> > Hello,
> >
> > The analogy of working on an old MG is rather appropriate here, and having
> > owned several of those in the past, I know exactly of what he speaks. LOL!
> >
> > ~Paul
> >
>
> At least an MG is easy to work on - by the sounds of it the SDS-9 is more like
> working on a Jaguar E-Type.
>
> Chris
> (former MGB-GT owner)
>

Anybody willing to trade an SDS9 fully working for an MG or Jaguar E-Type?

Michael

----- Original Message -----
From: Jonathan
To: Simmons_Drums@yahoogroups.com
Sent: Monday, May 20, 2013 4:05 PM
Subject: [Simmons Drums] Re: SDS 9 elementary problem & deeper fault





I totally get the analogy, but I'm with Chris - as an ex MG owner myself, they're not so bad to work on though and I would have thought the crammed-in effect and temperamental nature was more apt with an E-Type or primadonna Ferrari...
J

--- In Simmons_Drums@yahoogroups.com, "chris@..." <chris@...> wrote:
>
>
>
> On 19 May 2013 at 13:20 simmonssds7fan <ptmetcalf@...> wrote:
> > Hello,
> >
> > The analogy of working on an old MG is rather appropriate here, and having
> > owned several of those in the past, I know exactly of what he speaks. LOL!
> >
> > ~Paul
> >
>
> At least an MG is easy to work on - by the sounds of it the SDS-9 is more like
> working on a Jaguar E-Type.
>
> Chris
> (former MGB-GT owner)
>





[Non-text portions of this message have been removed]

> I can attest to Michael's statements that these can be a real pain when not working. He has been a big help to me lately with one of these SDS9 units as well. After having replaced all the caps on the board, not just the demux ones, I am back to square one as well. My next step is IC replacement, and hopefully it gets mine working again soon.

Any particular reason why you replaced the all the capacitors? Were they *all* faulty?

Don't just start ripping parts out and replacing them, without having some idea of why or whether or not it's likely to cause the symptoms you have. You've probably generated more faults than you had to begin with now...

--
Gordonjcp MM0YEQ

the capacitors are most likely to decay over time.

all of them suffer after 20-30 years in the field.

usually the power supply is first thing you fix, after which a unit will actually start working, but it's not until you update all the caps that it starts to sound as good or better than factory.

z




 
NEW ALLIANCE EAST!!!!

--------------------------------------


New Alliance East - Mastering

New Alliance East - Facebook

X :::: B :::: S




________________________________
From: gordonjcp <gordon@...>
To: Simmons_Drums@yahoogroups.com
Sent: Monday, May 20, 2013 2:32 PM
Subject: [Simmons Drums] Re: SDS 9 elementary problem & deeper fault



 

> I can attest to Michael's statements that these can be a real pain when not working. He has been a big help to me lately with one of these SDS9 units as well. After having replaced all the caps on the board, not just the demux ones, I am back to square one as well. My next step is IC replacement, and hopefully it gets mine working again soon.

Any particular reason why you replaced the all the capacitors? Were they *all* faulty?

Don't just start ripping parts out and replacing them, without having some idea of why or whether or not it's likely to cause the symptoms you have. You've probably generated more faults than you had to begin with now...

--
Gordonjcp MM0YEQ




[Non-text portions of this message have been removed]

Tell that to my 1950's Clavioline with original caps. ;)

The cap debate will go on, but no, I only replace those in need of
replacing.

--
electronically yours, jesper

- -- --- ---- ----- ---- --- -- -
www.electronic-obsession.se


Nick Zampiello skrev 2013-05-20 20:37:

> the capacitors are most likely to decay over time.
>
> all of them suffer after 20-30 years in the field.
>
> usually the power supply is first thing you fix, after which a unit will
> actually start working, but it's not until you update all the caps that
> it starts to sound as good or better than factory.
>
> z

right!

there's definitely times when you might not...

i thought this about my SDSV until i just did all of the caps not on the cards.

power supply and some on the back card seating board.

it was so much better sounding.

z


 
NEW ALLIANCE EAST!!!!

--------------------------------------


New Alliance East - Mastering

New Alliance East - Facebook

X :::: B :::: S




________________________________
From: jesper <jesper@...>
To: Simmons_Drums@yahoogroups.com
Sent: Monday, May 20, 2013 4:30 PM
Subject: Re: [Simmons Drums] Re: SDS 9 elementary problem & deeper fault



 
Tell that to my 1950's Clavioline with original caps. ;)

The cap debate will go on, but no, I only replace those in need of
replacing.

--
electronically yours, jesper

- -- --- ---- ----- ---- --- -- -
www.electronic-obsession.se

Nick Zampiello skrev 2013-05-20 20:37:

> the capacitors are most likely to decay over time.
>
> all of them suffer after 20-30 years in the field.
>
> usually the power supply is first thing you fix, after which a unit will
> actually start working, but it's not until you update all the caps that
> it starts to sound as good or better than factory.
>
> z

[Non-text portions of this message have been removed]

I replaced all of the caps that were the same value as the mux/demux circuits as advised by Michael Buchner (he said it was the mux/demux circuits), and that that was my issue with the machine. He said that they are usually worn out and are the major culprits of the problem I'm having with mine. It was a starting point.

If the mux/demux caps are worn out and ALL the caps are the same age on the board, wouldn't it make sense to change them all? They are cheap enough.

As I stated previously, that didn't change the issue I'm having with it, so now it has to be the mux/demux ICs, as stated earlier in this thread by Michael himself on the issue with this machine that this member is having.

If I've replaced all the caps with the proper values and it does the exact same thing it did before, how then could I have created more problems? Can you please explain that theory?

--- In Simmons_Drums@yahoogroups.com, "gordonjcp" <gordon@...> wrote:
>
>
> > I can attest to Michael's statements that these can be a real pain when not working. He has been a big help to me lately with one of these SDS9 units as well. After having replaced all the caps on the board, not just the demux ones, I am back to square one as well. My next step is IC replacement, and hopefully it gets mine working again soon.
>
> Any particular reason why you replaced the all the capacitors? Were they *all* faulty?
>
> Don't just start ripping parts out and replacing them, without having some idea of why or whether or not it's likely to cause the symptoms you have. You've probably generated more faults than you had to begin with now...
>
> --
> Gordonjcp MM0YEQ
>

If you're good at soldering it's no problem to switch caps. But that's a
common advice online and hence the scepticism. Michael knows what he's
talking about and you seems to know how to solder. But there are plenty
of stories from hobbyists digging into old gear causing soldering
bridges and other things making matters worse.

So my comment was not negative, just an advice to take it slow. But if
Michael adviced you to do it, it's a different matter. :D

--
electronically yours, jesper

- -- --- ---- ----- ---- --- -- -
www.electronic-obsession.se


simmonssds7fan skrev 2013-05-21 02:15:

> I replaced all of the caps that were the same value as the mux/demux
> circuits as advised by Michael Buchner (he said it was the mux/demux
> circuits), and that that was my issue with the machine. He said that
> they are usually worn out and are the major culprits of the problem I'm
> having with mine. It was a starting point.
>
> If the mux/demux caps are worn out and ALL the caps are the same age on
> the board, wouldn't it make sense to change them all? They are cheap enough.
>
> As I stated previously, that didn't change the issue I'm having with it,
> so now it has to be the mux/demux ICs, as stated earlier in this thread
> by Michael himself on the issue with this machine that this member is
> having.
>
> If I've replaced all the caps with the proper values and it does the
> exact same thing it did before, how then could I have created more
> problems? Can you please explain that theory?
>
> --- In Simmons_Drums@yahoogroups.com
> <mailto:Simmons_Drums%40yahoogroups.com>, "gordonjcp" <gordon@...> wrote:
> >
> >
> > > I can attest to Michael's statements that these can be a real pain
> when not working. He has been a big help to me lately with one of these
> SDS9 units as well. After having replaced all the caps on the board, not
> just the demux ones, I am back to square one as well. My next step is IC
> replacement, and hopefully it gets mine working again soon.
> >
> > Any particular reason why you replaced the all the capacitors? Were
> they *all* faulty?
> >
> > Don't just start ripping parts out and replacing them, without having
> some idea of why or whether or not it's likely to cause the symptoms you
> have. You've probably generated more faults than you had to begin with
> now...
> >
> > --
> > Gordonjcp MM0YEQ

About the caps, I'm facing 2 schools tech :
the one who is thinking logically than it's better to have new & full spec caps so they can provide their real electronic function... So it hsould end in a balanced result better than having random behaviours...

& the other one who says "NO", we change them if we have to & only if we have to...

But the fact is that 30 years after ... they are in theory ath the end of their Time.

Actually they are not necessary dead...
I also wonder if following the period of productions & marks, they are not all the same quality...

Were the ones used by Simmons some high quality ones ?
or cheaper to keep the cost production lower as possible... ??

We all know that, if the design & concept was top notch, Simmons was not top quality handcrafting, or mecanical engineering...

SO all your experiences guys about caps are really important to know !!

I have a vintage mixer with master fully recapped ... We have the tendancy to think that it's closer to original product like this than with some old drifting caps & components.

I'm not preaching for any of these 2 conceptions, both can be logical...
but I feel we all need to know about both & to experience about it !

Bless you :)
Patrice.













----- Mail d'origine -----
De: Nick Zampiello <newallianceeast@...>
À: Simmons Drums <Simmons_Drums@yahoogroups.com>
Envoyé: Mon, 20 May 2013 23:16:38 +0200 (CEST)
Objet: Re: [Simmons Drums] Re: SDS 9 elementary problem & deeper fault





right!


there's definitely times when you might not...


i thought this about my SDSV until i just did all of the caps not on the cards.


power supply and some on the back card seating board.


it was so much better sounding.


z




NEW ALLIANCE EAST!!!!


--------------------------------------


New Alliance East - Mastering


New Alliance East - Facebook


X :::: B :::: S


________________________________

From: jesper <jesper@...>

To: Simmons_Drums@yahoogroups.com

Sent: Monday, May 20, 2013 4:30 PM

Subject: Re: [Simmons Drums] Re: SDS 9 elementary problem & deeper fault





Tell that to my 1950's Clavioline with original caps. ;)


The cap debate will go on, but no, I only replace those in need of

replacing.


--

electronically yours, jesper


- -- --- ---- ----- ---- --- -- -

www.electronic-obsession.se


Nick Zampiello skrev 2013-05-20 20:37:

> the capacitors are most likely to decay over time.

>

> all of them suffer after 20-30 years in the field.

>

> usually the power supply is first thing you fix, after which a unit will

> actually start working, but it's not until you update all the caps that

> it starts to sound as good or better than factory.

>

> z

[Non-text portions of this message have been removed]





[Non-text portions of this message have been removed]

I'm therefore quite sure that every caps linked to powersupply should be replaced by security.
Less sure about the audio path... but well ...



----- Mail d'origine -----
De: Nick Zampiello <newallianceeast@...>
À: Simmons Drums <Simmons_Drums@yahoogroups.com>
Envoyé: Mon, 20 May 2013 23:16:38 +0200 (CEST)
Objet: Re: [Simmons Drums] Re: SDS 9 elementary problem & deeper fault





right!


there's definitely times when you might not...


i thought this about my SDSV until i just did all of the caps not on the cards.


power supply and some on the back card seating board.


it was so much better sounding.


z




NEW ALLIANCE EAST!!!!


--------------------------------------


New Alliance East - Mastering


New Alliance East - Facebook


X :::: B :::: S


________________________________

From: jesper <jesper@...>

To: Simmons_Drums@yahoogroups.com

Sent: Monday, May 20, 2013 4:30 PM

Subject: Re: [Simmons Drums] Re: SDS 9 elementary problem & deeper fault





Tell that to my 1950's Clavioline with original caps. ;)


The cap debate will go on, but no, I only replace those in need of

replacing.


--

electronically yours, jesper


- -- --- ---- ----- ---- --- -- -

www.electronic-obsession.se


Nick Zampiello skrev 2013-05-20 20:37:

> the capacitors are most likely to decay over time.

>

> all of them suffer after 20-30 years in the field.

>

> usually the power supply is first thing you fix, after which a unit will

> actually start working, but it's not until you update all the caps that

> it starts to sound as good or better than factory.

>

> z

[Non-text portions of this message have been removed]





[Non-text portions of this message have been removed]

My views after two minutes and not really thinking it through...

From experience: I've changed one (tantal, in a Variophon, anno 1982)
From laziness: Why change?
From electronics specs: Who wants to service my +50 machines? Drifting
shit makes analogues more juicy... ;)
From a practical view: Yes, PSU ones might be an idea, so that them
failing isn't destroying things on the boards. At least have a look
while there digging... But on the boards, why bother? Broken ones are
easy to locate if that happens.

A channel on my 1986 (?) mixer recently failed. Cap? Probably not, but
if it proves to be I'll probably dig into the rest too. That thing
really needs to work in my setup.

Regarding service my experience says that it's a failed IC in 90% of the
service cases. The most unusual fault was a burnt resistor (!) in a
SDS-IV (pet her for me Patrice!).

--
electronically yours, jesper

- -- --- ---- ----- ---- --- -- -
www.electronic-obsession.se



Jacquot.Patrice@... skrev 2013-05-21 19:30:

> About the caps, I'm facing 2 schools tech :
> the one who is thinking logically than it's better to have new & full
> spec caps so they can provide their real electronic function... So it
> hsould end in a balanced result better than having random behaviours...
>
> & the other one who says "NO", we change them if we have to & only if we
> have to...
>
> But the fact is that 30 years after ... they are in theory ath the end
> of their Time.
>
> Actually they are not necessary dead...
> I also wonder if following the period of productions & marks, they are
> not all the same quality...
>
> Were the ones used by Simmons some high quality ones ?
> or cheaper to keep the cost production lower as possible... ??
>
> We all know that, if the design & concept was top notch, Simmons was not
> top quality handcrafting, or mecanical engineering...
>
> SO all your experiences guys about caps are really important to know !!
>
> I have a vintage mixer with master fully recapped ... We have the
> tendancy to think that it's closer to original product like this than
> with some old drifting caps & components.
>
> I'm not preaching for any of these 2 conceptions, both can be logical...
> but I feel we all need to know about both & to experience about it !
>
> Bless you :)
> Patrice.
>
>
> ----- Mail d'origine -----
> De: Nick Zampiello <newallianceeast@...
> <mailto:newallianceeast%40yahoo.com>>
> À: Simmons Drums <Simmons_Drums@yahoogroups.com
> <mailto:Simmons_Drums%40yahoogroups.com>>
> Envoyé: Mon, 20 May 2013 23:16:38 +0200 (CEST)
> Objet: Re: [Simmons Drums] Re: SDS 9 elementary problem & deeper fault
>
> right!
>
> there's definitely times when you might not...
>
> i thought this about my SDSV until i just did all of the caps not on the
> cards.
>
> power supply and some on the back card seating board.
>
> it was so much better sounding.
>
> z
>
> NEW ALLIANCE EAST!!!!
>
> --------------------------------------
>
> New Alliance East - Mastering
>
> New Alliance East - Facebook
>
> X :::: B :::: S
>
> ________________________________
>
> From: jesper <jesper@...
> <mailto:jesper%40electronic-obsession.se>>
>
> To: Simmons_Drums@yahoogroups.com <mailto:Simmons_Drums%40yahoogroups.com>
>
> Sent: Monday, May 20, 2013 4:30 PM
>
> Subject: Re: [Simmons Drums] Re: SDS 9 elementary problem & deeper fault
>
> Tell that to my 1950's Clavioline with original caps. ;)
>
> The cap debate will go on, but no, I only replace those in need of
>
> replacing.
>
> --
>
> electronically yours, jesper
>
> - -- --- ---- ----- ---- --- -- -
>
> www.electronic-obsession.se
>
> Nick Zampiello skrev 2013-05-20 20:37:
>
> > the capacitors are most likely to decay over time.
>
> >
>
> > all of them suffer after 20-30 years in the field.
>
> >
>
> > usually the power supply is first thing you fix, after which a unit will
>
> > actually start working, but it's not until you update all the caps that
>
> > it starts to sound as good or better than factory.
>
> >
>
> > z

To be fair to Michael, I may have mis-understood what he originally told me in his original email to me. Possibly something lost in translation, as he is in Germany and I am in the USA (German to English and visa-versa) but he did say the caps get weak with age, so I understood that they are what needed replacement, which is why I replaced them. Having done so, it now seems that the problem is with the IC's rather than the caps in my case.

Is there a test to specifically condemn the IC's?

--- In Simmons_Drums@yahoogroups.com, jesper <jesper@...> wrote:
>
> My views after two minutes and not really thinking it through...
>
> From experience: I've changed one (tantal, in a Variophon, anno 1982)
> From laziness: Why change?
> From electronics specs: Who wants to service my +50 machines? Drifting
> shit makes analogues more juicy... ;)
> From a practical view: Yes, PSU ones might be an idea, so that them
> failing isn't destroying things on the boards. At least have a look
> while there digging... But on the boards, why bother? Broken ones are
> easy to locate if that happens.
>
> A channel on my 1986 (?) mixer recently failed. Cap? Probably not, but
> if it proves to be I'll probably dig into the rest too. That thing
> really needs to work in my setup.
>
> Regarding service my experience says that it's a failed IC in 90% of the
> service cases. The most unusual fault was a burnt resistor (!) in a
> SDS-IV (pet her for me Patrice!).
>
> --
> electronically yours, jesper
>
> - -- --- ---- ----- ---- --- -- -
> www.electronic-obsession.se
>
>
>
> Jacquot.Patrice@... skrev 2013-05-21 19:30:
> > About the caps, I'm facing 2 schools tech :
> > the one who is thinking logically than it's better to have new & full
> > spec caps so they can provide their real electronic function... So it
> > hsould end in a balanced result better than having random behaviours...
> >
> > & the other one who says "NO", we change them if we have to & only if we
> > have to...
> >
> > But the fact is that 30 years after ... they are in theory ath the end
> > of their Time.
> >
> > Actually they are not necessary dead...
> > I also wonder if following the period of productions & marks, they are
> > not all the same quality...
> >
> > Were the ones used by Simmons some high quality ones ?
> > or cheaper to keep the cost production lower as possible... ??
> >
> > We all know that, if the design & concept was top notch, Simmons was not
> > top quality handcrafting, or mecanical engineering...
> >
> > SO all your experiences guys about caps are really important to know !!
> >
> > I have a vintage mixer with master fully recapped ... We have the
> > tendancy to think that it's closer to original product like this than
> > with some old drifting caps & components.
> >
> > I'm not preaching for any of these 2 conceptions, both can be logical...
> > but I feel we all need to know about both & to experience about it !
> >
> > Bless you :)
> > Patrice.
> >
> >
> > ----- Mail d'origine -----
> > De: Nick Zampiello <newallianceeast@...
> > <mailto:newallianceeast%40yahoo.com>>
> > À: Simmons Drums <Simmons_Drums@yahoogroups.com
> > <mailto:Simmons_Drums%40yahoogroups.com>>
> > Envoyé: Mon, 20 May 2013 23:16:38 +0200 (CEST)
> > Objet: Re: [Simmons Drums] Re: SDS 9 elementary problem & deeper fault
> >
> > right!
> >
> > there's definitely times when you might not...
> >
> > i thought this about my SDSV until i just did all of the caps not on the
> > cards.
> >
> > power supply and some on the back card seating board.
> >
> > it was so much better sounding.
> >
> > z
> >
> > NEW ALLIANCE EAST!!!!
> >
> > --------------------------------------
> >
> > New Alliance East - Mastering
> >
> > New Alliance East - Facebook
> >
> > X :::: B :::: S
> >
> > ________________________________
> >
> > From: jesper <jesper@...
> > <mailto:jesper%40electronic-obsession.se>>
> >
> > To: Simmons_Drums@yahoogroups.com <mailto:Simmons_Drums%40yahoogroups.com>
> >
> > Sent: Monday, May 20, 2013 4:30 PM
> >
> > Subject: Re: [Simmons Drums] Re: SDS 9 elementary problem & deeper fault
> >
> > Tell that to my 1950's Clavioline with original caps. ;)
> >
> > The cap debate will go on, but no, I only replace those in need of
> >
> > replacing.
> >
> > --
> >
> > electronically yours, jesper
> >
> > - -- --- ---- ----- ---- --- -- -
> >
> > www.electronic-obsession.se
> >
> > Nick Zampiello skrev 2013-05-20 20:37:
> >
> > > the capacitors are most likely to decay over time.
> >
> > >
> >
> > > all of them suffer after 20-30 years in the field.
> >
> > >
> >
> > > usually the power supply is first thing you fix, after which a unit will
> >
> > > actually start working, but it's not until you update all the caps that
> >
> > > it starts to sound as good or better than factory.
> >
> > >
> >
> > > z
>

simmonssds7fan skrev 2013-05-21 21:17:

> Is there a test to specifically condemn the IC's?

No, since IC's are small boxes of more or less standard solutions.
An oscillator is no flip-flop divider and a triple gate is no
operational amplifier. BUT... when you find a wrecked IC - make sure to
put the new one in a socket to make it easier for future generations of
techs. :D

--
electronically yours, jesper

- -- --- ---- ----- ---- --- -- -
www.electronic-obsession.se

> If the mux/demux caps are worn out and ALL the caps are the same age on the board, wouldn't it make sense to change them all? They are cheap enough.

They don't wear out. They rarely fail. When they do, they cause very, very distinctive faults.

It's worth noting that just about the only capacitors I have ever seen fail have been electrolytics used in cheap crappy switched-mode power supplies (which you don't have here) and disc ceramics used at high voltage or in RF amps. In synthesizers I've changed maybe a dozen genuinely faulty capacitors in 20-odd years.

Capacitors don't fail, and they don't wear out.

> As I stated previously, that didn't change the issue I'm having with it, so now it has to be the mux/demux ICs, as stated earlier in this thread by Michael himself on the issue with this machine that this member is having.

Of course it didn't, and now you've got to do what you should have done to begin with - diagnose the fault! The 405x family multiplexers do fail, with either an output getting "stuck" usually to one supply rail or the other, or the inputs just not switching at all. Get an oscilloscope, track down the fault, and replace just the part that has failed.

> If I've replaced all the caps with the proper values and it does the exact same thing it did before, how then could I have created more problems? Can you please explain that theory?

How good is your soldering? Are you sure you read all those capacitors correctly? Are you sure you didn't damage the fragile through-hole plating on the boards? Are you sure you didn't zap something with static?

I won't touch *anything* that's been "re-capped". I often see synths that have been "re-capped" by some Expert Synth Doctor that then never quite works right again, and then they're just too much bother to put right.

Don't muck about. Track the fault down and fix *just that fault*.

--
Gordonjcp MM0YEQ

i bought a JP6 from a guy that had a 'pro' 'fix' the bender board.

but neither the LFO 2 or bender worked.

upon inspection he had all of the transistors and caps in backwards!
 
it's too easy to make this mistake even for people who do it often!


NEW ALLIANCE EAST!!!!

--------------------------------------


New Alliance East - Mastering

New Alliance East - Facebook

X :::: B :::: S




________________________________
From: gordonjcp <gordon@...>
To: Simmons_Drums@yahoogroups.com
Sent: Tuesday, May 21, 2013 5:38 PM
Subject: [Simmons Drums] Re: SDS 9 elementary problem & deeper fault



 

> If the mux/demux caps are worn out and ALL the caps are the same age on the board, wouldn't it make sense to change them all? They are cheap enough.

They don't wear out. They rarely fail. When they do, they cause very, very distinctive faults.

It's worth noting that just about the only capacitors I have ever seen fail have been electrolytics used in cheap crappy switched-mode power supplies (which you don't have here) and disc ceramics used at high voltage or in RF amps. In synthesizers I've changed maybe a dozen genuinely faulty capacitors in 20-odd years.

Capacitors don't fail, and they don't wear out.

> As I stated previously, that didn't change the issue I'm having with it, so now it has to be the mux/demux ICs, as stated earlier in this thread by Michael himself on the issue with this machine that this member is having.

Of course it didn't, and now you've got to do what you should have done to begin with - diagnose the fault! The 405x family multiplexers do fail, with either an output getting "stuck" usually to one supply rail or the other, or the inputs just not switching at all. Get an oscilloscope, track down the fault, and replace just the part that has failed.

> If I've replaced all the caps with the proper values and it does the exact same thing it did before, how then could I have created more problems? Can you please explain that theory?

How good is your soldering? Are you sure you read all those capacitors correctly? Are you sure you didn't damage the fragile through-hole plating on the boards? Are you sure you didn't zap something with static?

I won't touch *anything* that's been "re-capped". I often see synths that have been "re-capped" by some Expert Synth Doctor that then never quite works right again, and then they're just too much bother to put right.

Don't muck about. Track the fault down and fix *just that fault*.

--
Gordonjcp MM0YEQ




[Non-text portions of this message have been removed]

Alright then.....let me run the issue by you then and see what you think it is.

When you power it up, it initializes normally. Then the low tom circuit trigger led comes on and sound is faintly generated, sounds like a constant "doom-doom-doom", then it slowly stops. After the low tom stops any one of the other toms or snare will trigger randomly at full volume until they are all triggering at the same time, generating a buzz/white noise. The bass channel never does this, only the snare/rim, and the toms. The unit gets rather warm when it does this. If you shut it off and let it sit until it gets back to room temperature, it goes back to near normal and the cycle repeats. I have changed the OS chip to the 3.0 version, it did have the 4.0 version, but it only slightly helped.

Any ideas which mux/demux chip I should start with? I'm thinking the low tom, but I don't understand if it starts with that one and it goes off, how it could influence the others to randomly trigger like that. Wouldn't that mean they all have issues?

--- In Simmons_Drums@yahoogroups.com, "gordonjcp" <gordon@...> wrote:
>
>
> > If the mux/demux caps are worn out and ALL the caps are the same age on the board, wouldn't it make sense to change them all? They are cheap enough.
>
> They don't wear out. They rarely fail. When they do, they cause very, very distinctive faults.
>
> It's worth noting that just about the only capacitors I have ever seen fail have been electrolytics used in cheap crappy switched-mode power supplies (which you don't have here) and disc ceramics used at high voltage or in RF amps. In synthesizers I've changed maybe a dozen genuinely faulty capacitors in 20-odd years.
>
> Capacitors don't fail, and they don't wear out.
>
> > As I stated previously, that didn't change the issue I'm having with it, so now it has to be the mux/demux ICs, as stated earlier in this thread by Michael himself on the issue with this machine that this member is having.
>
> Of course it didn't, and now you've got to do what you should have done to begin with - diagnose the fault! The 405x family multiplexers do fail, with either an output getting "stuck" usually to one supply rail or the other, or the inputs just not switching at all. Get an oscilloscope, track down the fault, and replace just the part that has failed.
>
> > If I've replaced all the caps with the proper values and it does the exact same thing it did before, how then could I have created more problems? Can you please explain that theory?
>
> How good is your soldering? Are you sure you read all those capacitors correctly? Are you sure you didn't damage the fragile through-hole plating on the boards? Are you sure you didn't zap something with static?
>
> I won't touch *anything* that's been "re-capped". I often see synths that have been "re-capped" by some Expert Synth Doctor that then never quite works right again, and then they're just too much bother to put right.
>
> Don't muck about. Track the fault down and fix *just that fault*.
>
> --
> Gordonjcp MM0YEQ
>

Pardon the newbie if you feel that I somewhat offend with the following remarks but......isn't the point of this group to help others with their expertise (or lack thereof) in the repair and upkeep of these machines? Your post does not seem very helpful at all and rather mocking. My soldering skills are fine and no, I did not damage the board as I was very careful when removing the old components, nor was I worried about static as I was using the proper anti-static equipment. And yes, I am sure about the values of all those caps. I made sure of it before replacing all 100 of them that I had the correct values. I made doubly sure of it before I ordered them from an electronics supply house in the UK since they are not readily available here in the USA.

Again, mocking someone who is looking for help here who is not familiar with these particular machines is not very helpful. If you do have some real insight as to where I should continue to "find the fault" so I can fix it, that would be great. Otherwise, please keep your not very helpful comments to yourself.

--- In Simmons_Drums@yahoogroups.com, "gordonjcp" <gordon@...> wrote:
>
>
> > If the mux/demux caps are worn out and ALL the caps are the same age on the board, wouldn't it make sense to change them all? They are cheap enough.
>
> They don't wear out. They rarely fail. When they do, they cause very, very distinctive faults.
>
> It's worth noting that just about the only capacitors I have ever seen fail have been electrolytics used in cheap crappy switched-mode power supplies (which you don't have here) and disc ceramics used at high voltage or in RF amps. In synthesizers I've changed maybe a dozen genuinely faulty capacitors in 20-odd years.
>
> Capacitors don't fail, and they don't wear out.
>
> > As I stated previously, that didn't change the issue I'm having with it, so now it has to be the mux/demux ICs, as stated earlier in this thread by Michael himself on the issue with this machine that this member is having.
>
> Of course it didn't, and now you've got to do what you should have done to begin with - diagnose the fault! The 405x family multiplexers do fail, with either an output getting "stuck" usually to one supply rail or the other, or the inputs just not switching at all. Get an oscilloscope, track down the fault, and replace just the part that has failed.
>
> > If I've replaced all the caps with the proper values and it does the exact same thing it did before, how then could I have created more problems? Can you please explain that theory?
>
> How good is your soldering? Are you sure you read all those capacitors correctly? Are you sure you didn't damage the fragile through-hole plating on the boards? Are you sure you didn't zap something with static?
>
> I won't touch *anything* that's been "re-capped". I often see synths that have been "re-capped" by some Expert Synth Doctor that then never quite works right again, and then they're just too much bother to put right.
>
> Don't muck about. Track the fault down and fix *just that fault*.
>
> --
> Gordonjcp MM0YEQ
>

simmonssds7fan skrev 2013-05-22 02:08:

> Pardon the newbie if you feel that I somewhat offend with the following
> remarks but......isn't the point of this group to help others with their
> expertise (or lack thereof) in the repair and upkeep of these machines?

Among other things, yes. It's certainly noones intention to offend nor
not helping...

> Your post does not seem very helpful at all and rather mocking. My
> soldering skills are fine and no, I did not damage the board as I was
> very careful when removing the old components, nor was I worried about
> static as I was using the proper anti-static equipment. And yes, I am
> sure about the values of all those caps. I made sure of it before
> replacing all 100 of them that I had the correct values. I made doubly
> sure of it before I ordered them from an electronics supply house in the
> UK since they are not readily available here in the USA.
>
> Again, mocking someone who is looking for help here who is not familiar
> with these particular machines is not very helpful. If you do have some
> real insight as to where I should continue to "find the fault" so I can
> fix it, that would be great. Otherwise, please keep your not very
> helpful comments to yourself.

I don't think his intention was to mock. But it's easy to misunderstand
eachother online.
Good that you made sure everything was correct. The biggest problem in
the Simmons world tend to be the SDS-9 (well, 7 too...). They have often
been gigged a lot and reliability was a question even back then.

I have no personal experience with the SDS-9 but I saw another post
coming along... maybe that'll give us some clues.

--
electronically yours, jesper

- -- --- ---- ----- ---- --- -- -
www.electronic-obsession.se

simmonssds7fan skrev 2013-05-22 01:53:

> Alright then.....let me run the issue by you then and see what you think
> it is.
>
> When you power it up, it initializes normally. Then the low tom circuit
> trigger led comes on and sound is faintly generated, sounds like a
> constant "doom-doom-doom", then it slowly stops. After the low tom stops
> any one of the other toms or snare will trigger randomly at full volume
> until they are all triggering at the same time, generating a buzz/white
> noise. The bass channel never does this, only the snare/rim, and the
> toms. The unit gets rather warm when it does this. If you shut it off
> and let it sit until it gets back to room temperature, it goes back to
> near normal and the cycle repeats. I have changed the OS chip to the 3.0
> version, it did have the 4.0 version, but it only slightly helped.
>
> Any ideas which mux/demux chip I should start with? I'm thinking the low
> tom, but I don't understand if it starts with that one and it goes off,
> how it could influence the others to randomly trigger like that.
> Wouldn't that mean they all have issues?

This may sound rudimentary, but have you checked the power lines? Any
fluctuations? Since it's running so hot that seems like the best bet...

Are the proms OK (thinking mainly the tom prom here)? As I understand
it, there's no noise on the bass drum channel, hence it being silent
when the snare/rim is going haywire. So that sounds reasonable.

Do the bass channel work? I mean, can you trigger it and tweak it while
the other are actin g crazy?

--
electronically yours, jesper

- -- --- ---- ----- ---- --- -- -
www.electronic-obsession.se

I'm from the "replace electrolytics caps" school. Especially the power supply section. I can't remember for sure, but think there are only half a dozen electrolytics on the board, and none of them doing anything "critical".

It's not unusual for an SDS9 to run hot (underneath) as that's where the PSU board is connected. Where in the world are you, and what is your mains voltage, as the transformer is multi-tapped and the unit will run quite happily on a higher tap, unless you're in the UK in which case you've got no choice :(.

With the box running and doing the random triggering, lick your finger and touch the top of all chips, see if any dry out quickly, an indication of them running hot.

Are you sure the ROM chip you replaced is fast enough (and is the RAM original for the same reason?)

Can you also check the +5V at various points on the board (esp. furthest away from where the power connector is). On one of mine I connected a 100uF or similar near the CPU chip just to help the power supply out and it stopped it doing odd things.

From memory, and I haven't checked the service manual recently, I recall there is a "full-on" test mode that you can put the unit into, can anyone else confirm ?

Phil.

--- In Simmons_Drums@yahoogroups.com, "simmonssds7fan" <ptmetcalf@...> wrote:
>
> Alright then.....let me run the issue by you then and see what you think it is.
>
> When you power it up, it initializes normally. Then the low tom circuit trigger led comes on and sound is faintly generated, sounds like a constant "doom-doom-doom", then it slowly stops. After the low tom stops any one of the other toms or snare will trigger randomly at full volume until they are all triggering at the same time, generating a buzz/white noise. The bass channel never does this, only the snare/rim, and the toms. The unit gets rather warm when it does this. If you shut it off and let it sit until it gets back to room temperature, it goes back to near normal and the cycle repeats. I have changed the OS chip to the 3.0 version, it did have the 4.0 version, but it only slightly helped.
>
> Any ideas which mux/demux chip I should start with? I'm thinking the low tom, but I don't understand if it starts with that one and it goes off, how it could influence the others to randomly trigger like that. Wouldn't that mean they all have issues?
>
> --- In Simmons_Drums@yahoogroups.com, "gordonjcp" <gordon@> wrote:
> >
> >
> > > If the mux/demux caps are worn out and ALL the caps are the same age on the board, wouldn't it make sense to change them all? They are cheap enough.
> >
> > They don't wear out. They rarely fail. When they do, they cause very, very distinctive faults.
> >
> > It's worth noting that just about the only capacitors I have ever seen fail have been electrolytics used in cheap crappy switched-mode power supplies (which you don't have here) and disc ceramics used at high voltage or in RF amps. In synthesizers I've changed maybe a dozen genuinely faulty capacitors in 20-odd years.
> >
> > Capacitors don't fail, and they don't wear out.
> >
> > > As I stated previously, that didn't change the issue I'm having with it, so now it has to be the mux/demux ICs, as stated earlier in this thread by Michael himself on the issue with this machine that this member is having.
> >
> > Of course it didn't, and now you've got to do what you should have done to begin with - diagnose the fault! The 405x family multiplexers do fail, with either an output getting "stuck" usually to one supply rail or the other, or the inputs just not switching at all. Get an oscilloscope, track down the fault, and replace just the part that has failed.
> >
> > > If I've replaced all the caps with the proper values and it does the exact same thing it did before, how then could I have created more problems? Can you please explain that theory?
> >
> > How good is your soldering? Are you sure you read all those capacitors correctly? Are you sure you didn't damage the fragile through-hole plating on the boards? Are you sure you didn't zap something with static?
> >
> > I won't touch *anything* that's been "re-capped". I often see synths that have been "re-capped" by some Expert Synth Doctor that then never quite works right again, and then they're just too much bother to put right.
> >
> > Don't muck about. Track the fault down and fix *just that fault*.
> >
> > --
> > Gordonjcp MM0YEQ
> >
>

The power supply works normally, no fluctuations and the voltage outputs are to spec. The toms do not use an eprom for sound generation on these, however, yes, the sound generation is normal sounding when they trigger, either when I do it or when the machine decides to do it randomly. The bass channel does work when manually triggered, and did trigger when using the built in autorun function. However, when it starts going haywire, the bass channel will no longer trigger. I think it is because the processor is overwhelmed by everything else going off at the same time though.

--- In Simmons_Drums@yahoogroups.com, jesper <jesper@...> wrote:
>
> simmonssds7fan skrev 2013-05-22 01:53:
> > Alright then.....let me run the issue by you then and see what you think
> > it is.
> >
> > When you power it up, it initializes normally. Then the low tom circuit
> > trigger led comes on and sound is faintly generated, sounds like a
> > constant "doom-doom-doom", then it slowly stops. After the low tom stops
> > any one of the other toms or snare will trigger randomly at full volume
> > until they are all triggering at the same time, generating a buzz/white
> > noise. The bass channel never does this, only the snare/rim, and the
> > toms. The unit gets rather warm when it does this. If you shut it off
> > and let it sit until it gets back to room temperature, it goes back to
> > near normal and the cycle repeats. I have changed the OS chip to the 3.0
> > version, it did have the 4.0 version, but it only slightly helped.
> >
> > Any ideas which mux/demux chip I should start with? I'm thinking the low
> > tom, but I don't understand if it starts with that one and it goes off,
> > how it could influence the others to randomly trigger like that.
> > Wouldn't that mean they all have issues?
>
> This may sound rudimentary, but have you checked the power lines? Any
> fluctuations? Since it's running so hot that seems like the best bet...
>
> Are the proms OK (thinking mainly the tom prom here)? As I understand
> it, there's no noise on the bass drum channel, hence it being silent
> when the snare/rim is going haywire. So that sounds reasonable.
>
> Do the bass channel work? I mean, can you trigger it and tweak it while
> the other are actin g crazy?
>
> --
> electronically yours, jesper
>
> - -- --- ---- ----- ---- --- -- -
> www.electronic-obsession.se
>

I replaced all the polyfilm caps that were rated at .1nf-63v on the board as I was told that these were "worn out and at the end of their useful life". I was also told that it was the ones in the mux/demux circuits that would be faulty specifically, that those are "usually the problem". It was my decision to replace all of them on the board of this value since I figured, if the mux/demux ones are worn out and they are all the same age, then it made sense to replace them all.
I'm in the USA and the power transformer is wired up to run at 115V.
The erpom chip I used for the 3.0 OS is of the same type as the original. It is an Intel 27128a chip. I bought a bought a bunch of NOS ones a while ago for extra sound proms for my sds7 and tested them all a while ago, and yes I did use a prom eraser to make sure it was good to go. Also, I do have a good prommer and know how to use it. I'm sure it's not in the OS EPROM since the unit does the same thing with the 3.0 as the 4.0 OS that was installed in it when I first got the machine.

I will try the "lick test" next......we'll see what happens next I guess...

--- In Simmons_Drums@yahoogroups.com, "philmurr" <philmurr@...> wrote:
>
> I'm from the "replace electrolytics caps" school. Especially the power supply section. I can't remember for sure, but think there are only half a dozen electrolytics on the board, and none of them doing anything "critical".
>
> It's not unusual for an SDS9 to run hot (underneath) as that's where the PSU board is connected. Where in the world are you, and what is your mains voltage, as the transformer is multi-tapped and the unit will run quite happily on a higher tap, unless you're in the UK in which case you've got no choice :(.
>
> With the box running and doing the random triggering, lick your finger and touch the top of all chips, see if any dry out quickly, an indication of them running hot.
>
> Are you sure the ROM chip you replaced is fast enough (and is the RAM original for the same reason?)
>
> Can you also check the +5V at various points on the board (esp. furthest away from where the power connector is). On one of mine I connected a 100uF or similar near the CPU chip just to help the power supply out and it stopped it doing odd things.
>
> From memory, and I haven't checked the service manual recently, I recall there is a "full-on" test mode that you can put the unit into, can anyone else confirm ?
>
> Phil.
>
> --- In Simmons_Drums@yahoogroups.com, "simmonssds7fan" <ptmetcalf@> wrote:
> >
> > Alright then.....let me run the issue by you then and see what you think it is.
> >
> > When you power it up, it initializes normally. Then the low tom circuit trigger led comes on and sound is faintly generated, sounds like a constant "doom-doom-doom", then it slowly stops. After the low tom stops any one of the other toms or snare will trigger randomly at full volume until they are all triggering at the same time, generating a buzz/white noise. The bass channel never does this, only the snare/rim, and the toms. The unit gets rather warm when it does this. If you shut it off and let it sit until it gets back to room temperature, it goes back to near normal and the cycle repeats. I have changed the OS chip to the 3.0 version, it did have the 4.0 version, but it only slightly helped.
> >
> > Any ideas which mux/demux chip I should start with? I'm thinking the low tom, but I don't understand if it starts with that one and it goes off, how it could influence the others to randomly trigger like that. Wouldn't that mean they all have issues?
> >
> > --- In Simmons_Drums@yahoogroups.com, "gordonjcp" <gordon@> wrote:
> > >
> > >
> > > > If the mux/demux caps are worn out and ALL the caps are the same age on the board, wouldn't it make sense to change them all? They are cheap enough.
> > >
> > > They don't wear out. They rarely fail. When they do, they cause very, very distinctive faults.
> > >
> > > It's worth noting that just about the only capacitors I have ever seen fail have been electrolytics used in cheap crappy switched-mode power supplies (which you don't have here) and disc ceramics used at high voltage or in RF amps. In synthesizers I've changed maybe a dozen genuinely faulty capacitors in 20-odd years.
> > >
> > > Capacitors don't fail, and they don't wear out.
> > >
> > > > As I stated previously, that didn't change the issue I'm having with it, so now it has to be the mux/demux ICs, as stated earlier in this thread by Michael himself on the issue with this machine that this member is having.
> > >
> > > Of course it didn't, and now you've got to do what you should have done to begin with - diagnose the fault! The 405x family multiplexers do fail, with either an output getting "stuck" usually to one supply rail or the other, or the inputs just not switching at all. Get an oscilloscope, track down the fault, and replace just the part that has failed.
> > >
> > > > If I've replaced all the caps with the proper values and it does the exact same thing it did before, how then could I have created more problems? Can you please explain that theory?
> > >
> > > How good is your soldering? Are you sure you read all those capacitors correctly? Are you sure you didn't damage the fragile through-hole plating on the boards? Are you sure you didn't zap something with static?
> > >
> > > I won't touch *anything* that's been "re-capped". I often see synths that have been "re-capped" by some Expert Synth Doctor that then never quite works right again, and then they're just too much bother to put right.
> > >
> > > Don't muck about. Track the fault down and fix *just that fault*.
> > >
> > > --
> > > Gordonjcp MM0YEQ
> > >
> >
>

Sorry, the cap value should have read 100nf-63v, or .1uf-63v, NOT .1nf it is early here...LOL!

--- In Simmons_Drums@yahoogroups.com, "simmonssds7fan" <ptmetcalf@...> wrote:
>
> I replaced all the polyfilm caps that were rated at .1nf-63v on the board as I was told that these were "worn out and at the end of their useful life". I was also told that it was the ones in the mux/demux circuits that would be faulty specifically, that those are "usually the problem". It was my decision to replace all of them on the board of this value since I figured, if the mux/demux ones are worn out and they are all the same age, then it made sense to replace them all.
> I'm in the USA and the power transformer is wired up to run at 115V.
> The erpom chip I used for the 3.0 OS is of the same type as the original. It is an Intel 27128a chip. I bought a bought a bunch of NOS ones a while ago for extra sound proms for my sds7 and tested them all a while ago, and yes I did use a prom eraser to make sure it was good to go. Also, I do have a good prommer and know how to use it. I'm sure it's not in the OS EPROM since the unit does the same thing with the 3.0 as the 4.0 OS that was installed in it when I first got the machine.
>
> I will try the "lick test" next......we'll see what happens next I guess...
>
> --- In Simmons_Drums@yahoogroups.com, "philmurr" <philmurr@> wrote:
> >
> > I'm from the "replace electrolytics caps" school. Especially the power supply section. I can't remember for sure, but think there are only half a dozen electrolytics on the board, and none of them doing anything "critical".
> >
> > It's not unusual for an SDS9 to run hot (underneath) as that's where the PSU board is connected. Where in the world are you, and what is your mains voltage, as the transformer is multi-tapped and the unit will run quite happily on a higher tap, unless you're in the UK in which case you've got no choice :(.
> >
> > With the box running and doing the random triggering, lick your finger and touch the top of all chips, see if any dry out quickly, an indication of them running hot.
> >
> > Are you sure the ROM chip you replaced is fast enough (and is the RAM original for the same reason?)
> >
> > Can you also check the +5V at various points on the board (esp. furthest away from where the power connector is). On one of mine I connected a 100uF or similar near the CPU chip just to help the power supply out and it stopped it doing odd things.
> >
> > From memory, and I haven't checked the service manual recently, I recall there is a "full-on" test mode that you can put the unit into, can anyone else confirm ?
> >
> > Phil.
> >
> > --- In Simmons_Drums@yahoogroups.com, "simmonssds7fan" <ptmetcalf@> wrote:
> > >
> > > Alright then.....let me run the issue by you then and see what you think it is.
> > >
> > > When you power it up, it initializes normally. Then the low tom circuit trigger led comes on and sound is faintly generated, sounds like a constant "doom-doom-doom", then it slowly stops. After the low tom stops any one of the other toms or snare will trigger randomly at full volume until they are all triggering at the same time, generating a buzz/white noise. The bass channel never does this, only the snare/rim, and the toms. The unit gets rather warm when it does this. If you shut it off and let it sit until it gets back to room temperature, it goes back to near normal and the cycle repeats. I have changed the OS chip to the 3.0 version, it did have the 4.0 version, but it only slightly helped.
> > >
> > > Any ideas which mux/demux chip I should start with? I'm thinking the low tom, but I don't understand if it starts with that one and it goes off, how it could influence the others to randomly trigger like that. Wouldn't that mean they all have issues?
> > >
> > > --- In Simmons_Drums@yahoogroups.com, "gordonjcp" <gordon@> wrote:
> > > >
> > > >
> > > > > If the mux/demux caps are worn out and ALL the caps are the same age on the board, wouldn't it make sense to change them all? They are cheap enough.
> > > >
> > > > They don't wear out. They rarely fail. When they do, they cause very, very distinctive faults.
> > > >
> > > > It's worth noting that just about the only capacitors I have ever seen fail have been electrolytics used in cheap crappy switched-mode power supplies (which you don't have here) and disc ceramics used at high voltage or in RF amps. In synthesizers I've changed maybe a dozen genuinely faulty capacitors in 20-odd years.
> > > >
> > > > Capacitors don't fail, and they don't wear out.
> > > >
> > > > > As I stated previously, that didn't change the issue I'm having with it, so now it has to be the mux/demux ICs, as stated earlier in this thread by Michael himself on the issue with this machine that this member is having.
> > > >
> > > > Of course it didn't, and now you've got to do what you should have done to begin with - diagnose the fault! The 405x family multiplexers do fail, with either an output getting "stuck" usually to one supply rail or the other, or the inputs just not switching at all. Get an oscilloscope, track down the fault, and replace just the part that has failed.
> > > >
> > > > > If I've replaced all the caps with the proper values and it does the exact same thing it did before, how then could I have created more problems? Can you please explain that theory?
> > > >
> > > > How good is your soldering? Are you sure you read all those capacitors correctly? Are you sure you didn't damage the fragile through-hole plating on the boards? Are you sure you didn't zap something with static?
> > > >
> > > > I won't touch *anything* that's been "re-capped". I often see synths that have been "re-capped" by some Expert Synth Doctor that then never quite works right again, and then they're just too much bother to put right.
> > > >
> > > > Don't muck about. Track the fault down and fix *just that fault*.
> > > >
> > > > --
> > > > Gordonjcp MM0YEQ
> > > >
> > >
> >
>

I had nearly 30 SDS9 in my shop for repair, in nearly all cases the fault was the demux. I repaired some SDS9 by changing the s/h caps, some by replacing the demux chips. To be honest: The last few times I cut out all these demux responsible parts (4051, TL 84 and the caps) at once and renewed everything, I saved a lot of time (testing and thinking) and the parts were not expensive.

The demux is built up like a matrix, meaning that one single demux chip is responsible for (example) low tom trigger, snare filter frequency, mid tom pitch a.s.o. I sent you the (brilliant) schematics of Thierry EPPHERRE, so you can see this there. It is NOT one demux chip responsible for ONE instrument.

If you touch the legs of the demux chips, while the unit is running, you should hear something changing, stopping or getting better or worse. You can apply pressure with your thumb and finger like you would want to pull the chip out. As long as you don't lick, your skin resistance is big enough that nothing can be damaged.

Good luck, and I bet 10 bucks on a faulty demux.

Michael




The "lick" test is ok, without licking.

----- Original Message -----
From: simmonssds7fan
To: Simmons_Drums@yahoogroups.com
Sent: Wednesday, May 22, 2013 11:57 AM
Subject: [Simmons Drums] Re: SDS 9 elementary problem & deeper fault



Sorry, the cap value should have read 100nf-63v, or .1uf-63v, NOT .1nf it is early here...LOL!

--- In Simmons_Drums@yahoogroups.com, "simmonssds7fan" <ptmetcalf@...> wrote:
>
> I replaced all the polyfilm caps that were rated at .1nf-63v on the board as I was told that these were "worn out and at the end of their useful life". I was also told that it was the ones in the mux/demux circuits that would be faulty specifically, that those are "usually the problem". It was my decision to replace all of them on the board of this value since I figured, if the mux/demux ones are worn out and they are all the same age, then it made sense to replace them all.
> I'm in the USA and the power transformer is wired up to run at 115V.
> The erpom chip I used for the 3.0 OS is of the same type as the original. It is an Intel 27128a chip. I bought a bought a bunch of NOS ones a while ago for extra sound proms for my sds7 and tested them all a while ago, and yes I did use a prom eraser to make sure it was good to go. Also, I do have a good prommer and know how to use it. I'm sure it's not in the OS EPROM since the unit does the same thing with the 3.0 as the 4.0 OS that was installed in it when I first got the machine.
>
> I will try the "lick test" next......we'll see what happens next I guess...
>
> --- In Simmons_Drums@yahoogroups.com, "philmurr" <philmurr@> wrote:
> >
> > I'm from the "replace electrolytics caps" school. Especially the power supply section. I can't remember for sure, but think there are only half a dozen electrolytics on the board, and none of them doing anything "critical".
> >
> > It's not unusual for an SDS9 to run hot (underneath) as that's where the PSU board is connected. Where in the world are you, and what is your mains voltage, as the transformer is multi-tapped and the unit will run quite happily on a higher tap, unless you're in the UK in which case you've got no choice :(.
> >
> > With the box running and doing the random triggering, lick your finger and touch the top of all chips, see if any dry out quickly, an indication of them running hot.
> >
> > Are you sure the ROM chip you replaced is fast enough (and is the RAM original for the same reason?)
> >
> > Can you also check the +5V at various points on the board (esp. furthest away from where the power connector is). On one of mine I connected a 100uF or similar near the CPU chip just to help the power supply out and it stopped it doing odd things.
> >
> > From memory, and I haven't checked the service manual recently, I recall there is a "full-on" test mode that you can put the unit into, can anyone else confirm ?
> >
> > Phil.
> >
> > --- In Simmons_Drums@yahoogroups.com, "simmonssds7fan" <ptmetcalf@> wrote:
> > >
> > > Alright then.....let me run the issue by you then and see what you think it is.
> > >
> > > When you power it up, it initializes normally. Then the low tom circuit trigger led comes on and sound is faintly generated, sounds like a constant "doom-doom-doom", then it slowly stops. After the low tom stops any one of the other toms or snare will trigger randomly at full volume until they are all triggering at the same time, generating a buzz/white noise. The bass channel never does this, only the snare/rim, and the toms. The unit gets rather warm when it does this. If you shut it off and let it sit until it gets back to room temperature, it goes back to near normal and the cycle repeats. I have changed the OS chip to the 3.0 version, it did have the 4.0 version, but it only slightly helped.
> > >
> > > Any ideas which mux/demux chip I should start with? I'm thinking the low tom, but I don't understand if it starts with that one and it goes off, how it could influence the others to randomly trigger like that. Wouldn't that mean they all have issues?
> > >
> > > --- In Simmons_Drums@yahoogroups.com, "gordonjcp" <gordon@> wrote:
> > > >
> > > >
> > > > > If the mux/demux caps are worn out and ALL the caps are the same age on the board, wouldn't it make sense to change them all? They are cheap enough.
> > > >
> > > > They don't wear out. They rarely fail. When they do, they cause very, very distinctive faults.
> > > >
> > > > It's worth noting that just about the only capacitors I have ever seen fail have been electrolytics used in cheap crappy switched-mode power supplies (which you don't have here) and disc ceramics used at high voltage or in RF amps. In synthesizers I've changed maybe a dozen genuinely faulty capacitors in 20-odd years.
> > > >
> > > > Capacitors don't fail, and they don't wear out.
> > > >
> > > > > As I stated previously, that didn't change the issue I'm having with it, so now it has to be the mux/demux ICs, as stated earlier in this thread by Michael himself on the issue with this machine that this member is having.
> > > >
> > > > Of course it didn't, and now you've got to do what you should have done to begin with - diagnose the fault! The 405x family multiplexers do fail, with either an output getting "stuck" usually to one supply rail or the other, or the inputs just not switching at all. Get an oscilloscope, track down the fault, and replace just the part that has failed.
> > > >
> > > > > If I've replaced all the caps with the proper values and it does the exact same thing it did before, how then could I have created more problems? Can you please explain that theory?
> > > >
> > > > How good is your soldering? Are you sure you read all those capacitors correctly? Are you sure you didn't damage the fragile through-hole plating on the boards? Are you sure you didn't zap something with static?
> > > >
> > > > I won't touch *anything* that's been "re-capped". I often see synths that have been "re-capped" by some Expert Synth Doctor that then never quite works right again, and then they're just too much bother to put right.
> > > >
> > > > Don't muck about. Track the fault down and fix *just that fault*.
> > > >
> > > > --
> > > > Gordonjcp MM0YEQ
> > > >
> > >
> >
>





[Non-text portions of this message have been removed]

So, you recommend replacing the tl84 chips as well? I was planning on starting with the 4051s first and the chip for IC61 as well, 74ls156 I believe, which all show to be multiplexer/demultiplexer chips by spec. The tl84 chips come up as "simple amplifier" chips when I search the specs on them, which as I see in the schematics are in the demux circuits. I realize that these are not that expensive, just wondering if it would really be necessary, as this is quite a bit of de-soldering and resoldering.....not that 100 caps wasn't.....

--- In Simmons_Drums@yahoogroups.com, "Michael Buchner" <buchnerelectronics@...> wrote:
>
> I had nearly 30 SDS9 in my shop for repair, in nearly all cases the fault was the demux. I repaired some SDS9 by changing the s/h caps, some by replacing the demux chips. To be honest: The last few times I cut out all these demux responsible parts (4051, TL 84 and the caps) at once and renewed everything, I saved a lot of time (testing and thinking) and the parts were not expensive.
>
> The demux is built up like a matrix, meaning that one single demux chip is responsible for (example) low tom trigger, snare filter frequency, mid tom pitch a.s.o. I sent you the (brilliant) schematics of Thierry EPPHERRE, so you can see this there. It is NOT one demux chip responsible for ONE instrument.
>
> If you touch the legs of the demux chips, while the unit is running, you should hear something changing, stopping or getting better or worse. You can apply pressure with your thumb and finger like you would want to pull the chip out. As long as you don't lick, your skin resistance is big enough that nothing can be damaged.
>
> Good luck, and I bet 10 bucks on a faulty demux.
>
> Michael
>
>
>
>
> The "lick" test is ok, without licking.
> ----- Original Message -----
> From: simmonssds7fan
> To: Simmons_Drums@yahoogroups.com
> Sent: Wednesday, May 22, 2013 11:57 AM
> Subject: [Simmons Drums] Re: SDS 9 elementary problem & deeper fault
>
>
>
> Sorry, the cap value should have read 100nf-63v, or .1uf-63v, NOT .1nf it is early here...LOL!
>
> --- In Simmons_Drums@yahoogroups.com, "simmonssds7fan" <ptmetcalf@> wrote:
> >
> > I replaced all the polyfilm caps that were rated at .1nf-63v on the board as I was told that these were "worn out and at the end of their useful life". I was also told that it was the ones in the mux/demux circuits that would be faulty specifically, that those are "usually the problem". It was my decision to replace all of them on the board of this value since I figured, if the mux/demux ones are worn out and they are all the same age, then it made sense to replace them all.
> > I'm in the USA and the power transformer is wired up to run at 115V.
> > The erpom chip I used for the 3.0 OS is of the same type as the original. It is an Intel 27128a chip. I bought a bought a bunch of NOS ones a while ago for extra sound proms for my sds7 and tested them all a while ago, and yes I did use a prom eraser to make sure it was good to go. Also, I do have a good prommer and know how to use it. I'm sure it's not in the OS EPROM since the unit does the same thing with the 3.0 as the 4.0 OS that was installed in it when I first got the machine.
> >
> > I will try the "lick test" next......we'll see what happens next I guess...
> >
> > --- In Simmons_Drums@yahoogroups.com, "philmurr" <philmurr@> wrote:
> > >
> > > I'm from the "replace electrolytics caps" school. Especially the power supply section. I can't remember for sure, but think there are only half a dozen electrolytics on the board, and none of them doing anything "critical".
> > >
> > > It's not unusual for an SDS9 to run hot (underneath) as that's where the PSU board is connected. Where in the world are you, and what is your mains voltage, as the transformer is multi-tapped and the unit will run quite happily on a higher tap, unless you're in the UK in which case you've got no choice :(.
> > >
> > > With the box running and doing the random triggering, lick your finger and touch the top of all chips, see if any dry out quickly, an indication of them running hot.
> > >
> > > Are you sure the ROM chip you replaced is fast enough (and is the RAM original for the same reason?)
> > >
> > > Can you also check the +5V at various points on the board (esp. furthest away from where the power connector is). On one of mine I connected a 100uF or similar near the CPU chip just to help the power supply out and it stopped it doing odd things.
> > >
> > > From memory, and I haven't checked the service manual recently, I recall there is a "full-on" test mode that you can put the unit into, can anyone else confirm ?
> > >
> > > Phil.
> > >
> > > --- In Simmons_Drums@yahoogroups.com, "simmonssds7fan" <ptmetcalf@> wrote:
> > > >
> > > > Alright then.....let me run the issue by you then and see what you think it is.
> > > >
> > > > When you power it up, it initializes normally. Then the low tom circuit trigger led comes on and sound is faintly generated, sounds like a constant "doom-doom-doom", then it slowly stops. After the low tom stops any one of the other toms or snare will trigger randomly at full volume until they are all triggering at the same time, generating a buzz/white noise. The bass channel never does this, only the snare/rim, and the toms. The unit gets rather warm when it does this. If you shut it off and let it sit until it gets back to room temperature, it goes back to near normal and the cycle repeats. I have changed the OS chip to the 3.0 version, it did have the 4.0 version, but it only slightly helped.
> > > >
> > > > Any ideas which mux/demux chip I should start with? I'm thinking the low tom, but I don't understand if it starts with that one and it goes off, how it could influence the others to randomly trigger like that. Wouldn't that mean they all have issues?
> > > >
> > > > --- In Simmons_Drums@yahoogroups.com, "gordonjcp" <gordon@> wrote:
> > > > >
> > > > >
> > > > > > If the mux/demux caps are worn out and ALL the caps are the same age on the board, wouldn't it make sense to change them all? They are cheap enough.
> > > > >
> > > > > They don't wear out. They rarely fail. When they do, they cause very, very distinctive faults.
> > > > >
> > > > > It's worth noting that just about the only capacitors I have ever seen fail have been electrolytics used in cheap crappy switched-mode power supplies (which you don't have here) and disc ceramics used at high voltage or in RF amps. In synthesizers I've changed maybe a dozen genuinely faulty capacitors in 20-odd years.
> > > > >
> > > > > Capacitors don't fail, and they don't wear out.
> > > > >
> > > > > > As I stated previously, that didn't change the issue I'm having with it, so now it has to be the mux/demux ICs, as stated earlier in this thread by Michael himself on the issue with this machine that this member is having.
> > > > >
> > > > > Of course it didn't, and now you've got to do what you should have done to begin with - diagnose the fault! The 405x family multiplexers do fail, with either an output getting "stuck" usually to one supply rail or the other, or the inputs just not switching at all. Get an oscilloscope, track down the fault, and replace just the part that has failed.
> > > > >
> > > > > > If I've replaced all the caps with the proper values and it does the exact same thing it did before, how then could I have created more problems? Can you please explain that theory?
> > > > >
> > > > > How good is your soldering? Are you sure you read all those capacitors correctly? Are you sure you didn't damage the fragile through-hole plating on the boards? Are you sure you didn't zap something with static?
> > > > >
> > > > > I won't touch *anything* that's been "re-capped". I often see synths that have been "re-capped" by some Expert Synth Doctor that then never quite works right again, and then they're just too much bother to put right.
> > > > >
> > > > > Don't muck about. Track the fault down and fix *just that fault*.
> > > > >
> > > > > --
> > > > > Gordonjcp MM0YEQ
> > > > >
> > > >
> > >
> >
>
>
>
>
>
> [Non-text portions of this message have been removed]
>

Start with the 4051s. In most cases...

Best

Michael

----- Original Message -----
From: simmonssds7fan
To: Simmons_Drums@yahoogroups.com
Sent: Wednesday, May 22, 2013 2:52 PM
Subject: [Simmons Drums] Re: SDS 9 elementary problem & deeper fault



So, you recommend replacing the tl84 chips as well? I was planning on starting with the 4051s first and the chip for IC61 as well, 74ls156 I believe, which all show to be multiplexer/demultiplexer chips by spec. The tl84 chips come up as "simple amplifier" chips when I search the specs on them, which as I see in the schematics are in the demux circuits. I realize that these are not that expensive, just wondering if it would really be necessary, as this is quite a bit of de-soldering and resoldering.....not that 100 caps wasn't.....

--- In Simmons_Drums@yahoogroups.com, "Michael Buchner" <buchnerelectronics@...> wrote:
>
> I had nearly 30 SDS9 in my shop for repair, in nearly all cases the fault was the demux. I repaired some SDS9 by changing the s/h caps, some by replacing the demux chips. To be honest: The last few times I cut out all these demux responsible parts (4051, TL 84 and the caps) at once and renewed everything, I saved a lot of time (testing and thinking) and the parts were not expensive.
>
> The demux is built up like a matrix, meaning that one single demux chip is responsible for (example) low tom trigger, snare filter frequency, mid tom pitch a.s.o. I sent you the (brilliant) schematics of Thierry EPPHERRE, so you can see this there. It is NOT one demux chip responsible for ONE instrument.
>
> If you touch the legs of the demux chips, while the unit is running, you should hear something changing, stopping or getting better or worse. You can apply pressure with your thumb and finger like you would want to pull the chip out. As long as you don't lick, your skin resistance is big enough that nothing can be damaged.
>
> Good luck, and I bet 10 bucks on a faulty demux.
>
> Michael
>
>
>
>
> The "lick" test is ok, without licking.
> ----- Original Message -----
> From: simmonssds7fan
> To: Simmons_Drums@yahoogroups.com
> Sent: Wednesday, May 22, 2013 11:57 AM
> Subject: [Simmons Drums] Re: SDS 9 elementary problem & deeper fault
>
>
>
> Sorry, the cap value should have read 100nf-63v, or .1uf-63v, NOT .1nf it is early here...LOL!
>
> --- In Simmons_Drums@yahoogroups.com, "simmonssds7fan" <ptmetcalf@> wrote:
> >
> > I replaced all the polyfilm caps that were rated at .1nf-63v on the board as I was told that these were "worn out and at the end of their useful life". I was also told that it was the ones in the mux/demux circuits that would be faulty specifically, that those are "usually the problem". It was my decision to replace all of them on the board of this value since I figured, if the mux/demux ones are worn out and they are all the same age, then it made sense to replace them all.
> > I'm in the USA and the power transformer is wired up to run at 115V.
> > The erpom chip I used for the 3.0 OS is of the same type as the original. It is an Intel 27128a chip. I bought a bought a bunch of NOS ones a while ago for extra sound proms for my sds7 and tested them all a while ago, and yes I did use a prom eraser to make sure it was good to go. Also, I do have a good prommer and know how to use it. I'm sure it's not in the OS EPROM since the unit does the same thing with the 3.0 as the 4.0 OS that was installed in it when I first got the machine.
> >
> > I will try the "lick test" next......we'll see what happens next I guess...
> >
> > --- In Simmons_Drums@yahoogroups.com, "philmurr" <philmurr@> wrote:
> > >
> > > I'm from the "replace electrolytics caps" school. Especially the power supply section. I can't remember for sure, but think there are only half a dozen electrolytics on the board, and none of them doing anything "critical".
> > >
> > > It's not unusual for an SDS9 to run hot (underneath) as that's where the PSU board is connected. Where in the world are you, and what is your mains voltage, as the transformer is multi-tapped and the unit will run quite happily on a higher tap, unless you're in the UK in which case you've got no choice :(.
> > >
> > > With the box running and doing the random triggering, lick your finger and touch the top of all chips, see if any dry out quickly, an indication of them running hot.
> > >
> > > Are you sure the ROM chip you replaced is fast enough (and is the RAM original for the same reason?)
> > >
> > > Can you also check the +5V at various points on the board (esp. furthest away from where the power connector is). On one of mine I connected a 100uF or similar near the CPU chip just to help the power supply out and it stopped it doing odd things.
> > >
> > > From memory, and I haven't checked the service manual recently, I recall there is a "full-on" test mode that you can put the unit into, can anyone else confirm ?
> > >
> > > Phil.
> > >
> > > --- In Simmons_Drums@yahoogroups.com, "simmonssds7fan" <ptmetcalf@> wrote:
> > > >
> > > > Alright then.....let me run the issue by you then and see what you think it is.
> > > >
> > > > When you power it up, it initializes normally. Then the low tom circuit trigger led comes on and sound is faintly generated, sounds like a constant "doom-doom-doom", then it slowly stops. After the low tom stops any one of the other toms or snare will trigger randomly at full volume until they are all triggering at the same time, generating a buzz/white noise. The bass channel never does this, only the snare/rim, and the toms. The unit gets rather warm when it does this. If you shut it off and let it sit until it gets back to room temperature, it goes back to near normal and the cycle repeats. I have changed the OS chip to the 3.0 version, it did have the 4.0 version, but it only slightly helped.
> > > >
> > > > Any ideas which mux/demux chip I should start with? I'm thinking the low tom, but I don't understand if it starts with that one and it goes off, how it could influence the others to randomly trigger like that. Wouldn't that mean they all have issues?
> > > >
> > > > --- In Simmons_Drums@yahoogroups.com, "gordonjcp" <gordon@> wrote:
> > > > >
> > > > >
> > > > > > If the mux/demux caps are worn out and ALL the caps are the same age on the board, wouldn't it make sense to change them all? They are cheap enough.
> > > > >
> > > > > They don't wear out. They rarely fail. When they do, they cause very, very distinctive faults.
> > > > >
> > > > > It's worth noting that just about the only capacitors I have ever seen fail have been electrolytics used in cheap crappy switched-mode power supplies (which you don't have here) and disc ceramics used at high voltage or in RF amps. In synthesizers I've changed maybe a dozen genuinely faulty capacitors in 20-odd years.
> > > > >
> > > > > Capacitors don't fail, and they don't wear out.
> > > > >
> > > > > > As I stated previously, that didn't change the issue I'm having with it, so now it has to be the mux/demux ICs, as stated earlier in this thread by Michael himself on the issue with this machine that this member is having.
> > > > >
> > > > > Of course it didn't, and now you've got to do what you should have done to begin with - diagnose the fault! The 405x family multiplexers do fail, with either an output getting "stuck" usually to one supply rail or the other, or the inputs just not switching at all. Get an oscilloscope, track down the fault, and replace just the part that has failed.
> > > > >
> > > > > > If I've replaced all the caps with the proper values and it does the exact same thing it did before, how then could I have created more problems? Can you please explain that theory?
> > > > >
> > > > > How good is your soldering? Are you sure you read all those capacitors correctly? Are you sure you didn't damage the fragile through-hole plating on the boards? Are you sure you didn't zap something with static?
> > > > >
> > > > > I won't touch *anything* that's been "re-capped". I often see synths that have been "re-capped" by some Expert Synth Doctor that then never quite works right again, and then they're just too much bother to put right.
> > > > >
> > > > > Don't muck about. Track the fault down and fix *just that fault*.
> > > > >
> > > > > --
> > > > > Gordonjcp MM0YEQ
> > > > >
> > > >
> > >
> >
>
>
>
>
>
> [Non-text portions of this message have been removed]
>





[Non-text portions of this message have been removed]

I guess I will confirm you that suspicions quite soon , as my both 9 are asthmatic at the moment ;)
funny enough at the same moment actually.

Michael is it a lot of time consuming that Demux stuff to check & change ?

thx for your precious advice.


----- Mail d'origine -----
De: Michael Buchner <buchnerelectronics@...>
À: Simmons Drums <Simmons_Drums@yahoogroups.com>
Envoyé: Wed, 22 May 2013 14:34:32 +0200 (CEST)
Objet: Re: [Simmons Drums] Re: SDS 9 elementary problem & deeper fault





I had nearly 30 SDS9 in my shop for repair, in nearly all cases the fault was the demux. I repaired some SDS9 by changing the s/h caps, some by replacing the demux chips. To be honest: The last few times I cut out all these demux responsible parts (4051, TL 84 and the caps) at once and renewed everything, I saved a lot of time (testing and thinking) and the parts were not expensive.


The demux is built up like a matrix, meaning that one single demux chip is responsible for (example) low tom trigger, snare filter frequency, mid tom pitch a.s.o. I sent you the (brilliant) schematics of Thierry EPPHERRE, so you can see this there. It is NOT one demux chip responsible for ONE instrument.


If you touch the legs of the demux chips, while the unit is running, you should hear something changing, stopping or getting better or worse. You can apply pressure with your thumb and finger like you would want to pull the chip out. As long as you don't lick, your skin resistance is big enough that nothing can be damaged.


Good luck, and I bet 10 bucks on a faulty demux.


Michael


The "lick" test is ok, without licking.

----- Original Message -----

From: simmonssds7fan

To: Simmons_Drums@yahoogroups.com

Sent: Wednesday, May 22, 2013 11:57 AM

Subject: [Simmons Drums] Re: SDS 9 elementary problem & deeper fault


Sorry, the cap value should have read 100nf-63v, or .1uf-63v, NOT .1nf it is early here...LOL!


--- In Simmons_Drums@yahoogroups.com, "simmonssds7fan" <ptmetcalf@...> wrote:

>

> I replaced all the polyfilm caps that were rated at .1nf-63v on the board as I was told that these were "worn out and at the end of their useful life". I was also told that it was the ones in the mux/demux circuits that would be faulty specifically, that those are "usually the problem". It was my decision to replace all of them on the board of this value since I figured, if the mux/demux ones are worn out and they are all the same age, then it made sense to replace them all.

> I'm in the USA and the power transformer is wired up to run at 115V.

> The erpom chip I used for the 3.0 OS is of the same type as the original. It is an Intel 27128a chip. I bought a bought a bunch of NOS ones a while ago for extra sound proms for my sds7 and tested them all a while ago, and yes I did use a prom eraser to make sure it was good to go. Also, I do have a good prommer and know how to use it. I'm sure it's not in the OS EPROM since the unit does the same thing with the 3.0 as the 4.0 OS that was installed in it when I first got the machine.

>

> I will try the "lick test" next......we'll see what happens next I guess...

>

> --- In Simmons_Drums@yahoogroups.com, "philmurr" <philmurr@> wrote:

> >

> > I'm from the "replace electrolytics caps" school. Especially the power supply section. I can't remember for sure, but think there are only half a dozen electrolytics on the board, and none of them doing anything "critical".

> >

> > It's not unusual for an SDS9 to run hot (underneath) as that's where the PSU board is connected. Where in the world are you, and what is your mains voltage, as the transformer is multi-tapped and the unit will run quite happily on a higher tap, unless you're in the UK in which case you've got no choice :(.

> >

> > With the box running and doing the random triggering, lick your finger and touch the top of all chips, see if any dry out quickly, an indication of them running hot.

> >

> > Are you sure the ROM chip you replaced is fast enough (and is the RAM original for the same reason?)

> >

> > Can you also check the +5V at various points on the board (esp. furthest away from where the power connector is). On one of mine I connected a 100uF or similar near the CPU chip just to help the power supply out and it stopped it doing odd things.

> >

> > From memory, and I haven't checked the service manual recently, I recall there is a "full-on" test mode that you can put the unit into, can anyone else confirm ?

> >

> > Phil.

> >

> > --- In Simmons_Drums@yahoogroups.com, "simmonssds7fan" <ptmetcalf@> wrote:

> > >

> > > Alright then.....let me run the issue by you then and see what you think it is.

> > >

> > > When you power it up, it initializes normally. Then the low tom circuit trigger led comes on and sound is faintly generated, sounds like a constant "doom-doom-doom", then it slowly stops. After the low tom stops any one of the other toms or snare will trigger randomly at full volume until they are all triggering at the same time, generating a buzz/white noise. The bass channel never does this, only the snare/rim, and the toms. The unit gets rather warm when it does this. If you shut it off and let it sit until it gets back to room temperature, it goes back to near normal and the cycle repeats. I have changed the OS chip to the 3.0 version, it did have the 4.0 version, but it only slightly helped.

> > >

> > > Any ideas which mux/demux chip I should start with? I'm thinking the low tom, but I don't understand if it starts with that one and it goes off, how it could influence the others to randomly trigger like that. Wouldn't that mean they all have issues?

> > >

> > > --- In Simmons_Drums@yahoogroups.com, "gordonjcp" <gordon@> wrote:

> > > >

> > > >

> > > > > If the mux/demux caps are worn out and ALL the caps are the same age on the board, wouldn't it make sense to change them all? They are cheap enough.

> > > >

> > > > They don't wear out. They rarely fail. When they do, they cause very, very distinctive faults.

> > > >

> > > > It's worth noting that just about the only capacitors I have ever seen fail have been electrolytics used in cheap crappy switched-mode power supplies (which you don't have here) and disc ceramics used at high voltage or in RF amps. In synthesizers I've changed maybe a dozen genuinely faulty capacitors in 20-odd years.

> > > >

> > > > Capacitors don't fail, and they don't wear out.

> > > >

> > > > > As I stated previously, that didn't change the issue I'm having with it, so now it has to be the mux/demux ICs, as stated earlier in this thread by Michael himself on the issue with this machine that this member is having.

> > > >

> > > > Of course it didn't, and now you've got to do what you should have done to begin with - diagnose the fault! The 405x family multiplexers do fail, with either an output getting "stuck" usually to one supply rail or the other, or the inputs just not switching at all. Get an oscilloscope, track down the fault, and replace just the part that has failed.

> > > >

> > > > > If I've replaced all the caps with the proper values and it does the exact same thing it did before, how then could I have created more problems? Can you please explain that theory?

> > > >

> > > > How good is your soldering? Are you sure you read all those capacitors correctly? Are you sure you didn't damage the fragile through-hole plating on the boards? Are you sure you didn't zap something with static?

> > > >

> > > > I won't touch *anything* that's been "re-capped". I often see synths that have been "re-capped" by some Expert Synth Doctor that then never quite works right again, and then they're just too much bother to put right.

> > > >

> > > > Don't muck about. Track the fault down and fix *just that fault*.

> > > >

> > > > --

> > > > Gordonjcp MM0YEQ

> > > >

> > >

> >

>


[Non-text portions of this message have been removed]





[Non-text portions of this message have been removed]

Jacquot.Patrice@... skrev 2013-05-22 16:24:

> I guess I will confirm you that suspicions quite soon , as my both 9 are
> asthmatic at the moment ;)
> funny enough at the same moment actually.

Factory stereo mod? ;)

--
electronically yours, jesper

- -- --- ---- ----- ---- --- -- -
www.electronic-obsession.se

lol ! yep probably...
suspicious excessive solidarity ^^



----- Mail d'origine -----
De: jesper <jesper@...>
À: Simmons Drums <Simmons_Drums@yahoogroups.com>
Envoyé: Wed, 22 May 2013 16:31:56 +0200 (CEST)
Objet: Re: Re : Re: [Simmons Drums] Re: SDS 9 elementary problem & deeper fault





Jacquot.Patrice@... skrev 2013-05-22 16:24:

> I guess I will confirm you that suspicions quite soon , as my both 9 are

> asthmatic at the moment ;)

> funny enough at the same moment actually.

Factory stereo mod? ;)


--

electronically yours, jesper


- -- --- ---- ----- ---- --- -- -

www.electronic-obsession.se




[Non-text portions of this message have been removed]

I can tell you from personal experience that it took the better part of two afternoons to de-solder the old caps and solder in the new ones (but as I stated before I replaced all 100 caps that were of the same value on the board, probably overkill, but since I was there....) I can only imagine how long it will take to replace the six 4051 chips and the one other that controlls them (16 pins each chip). Michael mentioned possible replacement of all the tl84 chips as well, which I believe there are 20 sum such of them on the board (14 pins each).

--- In Simmons_Drums@yahoogroups.com, Jacquot.Patrice@... wrote:
>
> I guess I will confirm you that suspicions quite soon , as my both 9 are asthmatic at the moment ;)
> funny enough at the same moment actually.
>
> Michael is it a lot of time consuming that Demux stuff to check & change ?
>
> thx for your precious advice.
>
>
> ----- Mail d'origine -----
> De: Michael Buchner <buchnerelectronics@...>
> À: Simmons Drums <Simmons_Drums@yahoogroups.com>
> Envoyé: Wed, 22 May 2013 14:34:32 +0200 (CEST)
> Objet: Re: [Simmons Drums] Re: SDS 9 elementary problem & deeper fault
>
>
>
>
>
> I had nearly 30 SDS9 in my shop for repair, in nearly all cases the fault was the demux. I repaired some SDS9 by changing the s/h caps, some by replacing the demux chips. To be honest: The last few times I cut out all these demux responsible parts (4051, TL 84 and the caps) at once and renewed everything, I saved a lot of time (testing and thinking) and the parts were not expensive.
>
>
> The demux is built up like a matrix, meaning that one single demux chip is responsible for (example) low tom trigger, snare filter frequency, mid tom pitch a.s.o. I sent you the (brilliant) schematics of Thierry EPPHERRE, so you can see this there. It is NOT one demux chip responsible for ONE instrument.
>
>
> If you touch the legs of the demux chips, while the unit is running, you should hear something changing, stopping or getting better or worse. You can apply pressure with your thumb and finger like you would want to pull the chip out. As long as you don't lick, your skin resistance is big enough that nothing can be damaged.
>
>
> Good luck, and I bet 10 bucks on a faulty demux.
>
>
> Michael
>
>
> The "lick" test is ok, without licking.
>
> ----- Original Message -----
>
> From: simmonssds7fan
>
> To: Simmons_Drums@yahoogroups.com
>
> Sent: Wednesday, May 22, 2013 11:57 AM
>
> Subject: [Simmons Drums] Re: SDS 9 elementary problem & deeper fault
>
>
> Sorry, the cap value should have read 100nf-63v, or .1uf-63v, NOT .1nf it is early here...LOL!
>
>
> --- In Simmons_Drums@yahoogroups.com, "simmonssds7fan" <ptmetcalf@> wrote:
>
> >
>
> > I replaced all the polyfilm caps that were rated at .1nf-63v on the board as I was told that these were "worn out and at the end of their useful life". I was also told that it was the ones in the mux/demux circuits that would be faulty specifically, that those are "usually the problem". It was my decision to replace all of them on the board of this value since I figured, if the mux/demux ones are worn out and they are all the same age, then it made sense to replace them all.
>
> > I'm in the USA and the power transformer is wired up to run at 115V.
>
> > The erpom chip I used for the 3.0 OS is of the same type as the original. It is an Intel 27128a chip. I bought a bought a bunch of NOS ones a while ago for extra sound proms for my sds7 and tested them all a while ago, and yes I did use a prom eraser to make sure it was good to go. Also, I do have a good prommer and know how to use it. I'm sure it's not in the OS EPROM since the unit does the same thing with the 3.0 as the 4.0 OS that was installed in it when I first got the machine.
>
> >
>
> > I will try the "lick test" next......we'll see what happens next I guess...
>
> >
>
> > --- In Simmons_Drums@yahoogroups.com, "philmurr" <philmurr@> wrote:
>
> > >
>
> > > I'm from the "replace electrolytics caps" school. Especially the power supply section. I can't remember for sure, but think there are only half a dozen electrolytics on the board, and none of them doing anything "critical".
>
> > >
>
> > > It's not unusual for an SDS9 to run hot (underneath) as that's where the PSU board is connected. Where in the world are you, and what is your mains voltage, as the transformer is multi-tapped and the unit will run quite happily on a higher tap, unless you're in the UK in which case you've got no choice :(.
>
> > >
>
> > > With the box running and doing the random triggering, lick your finger and touch the top of all chips, see if any dry out quickly, an indication of them running hot.
>
> > >
>
> > > Are you sure the ROM chip you replaced is fast enough (and is the RAM original for the same reason?)
>
> > >
>
> > > Can you also check the +5V at various points on the board (esp. furthest away from where the power connector is). On one of mine I connected a 100uF or similar near the CPU chip just to help the power supply out and it stopped it doing odd things.
>
> > >
>
> > > From memory, and I haven't checked the service manual recently, I recall there is a "full-on" test mode that you can put the unit into, can anyone else confirm ?
>
> > >
>
> > > Phil.
>
> > >
>
> > > --- In Simmons_Drums@yahoogroups.com, "simmonssds7fan" <ptmetcalf@> wrote:
>
> > > >
>
> > > > Alright then.....let me run the issue by you then and see what you think it is.
>
> > > >
>
> > > > When you power it up, it initializes normally. Then the low tom circuit trigger led comes on and sound is faintly generated, sounds like a constant "doom-doom-doom", then it slowly stops. After the low tom stops any one of the other toms or snare will trigger randomly at full volume until they are all triggering at the same time, generating a buzz/white noise. The bass channel never does this, only the snare/rim, and the toms. The unit gets rather warm when it does this. If you shut it off and let it sit until it gets back to room temperature, it goes back to near normal and the cycle repeats. I have changed the OS chip to the 3.0 version, it did have the 4.0 version, but it only slightly helped.
>
> > > >
>
> > > > Any ideas which mux/demux chip I should start with? I'm thinking the low tom, but I don't understand if it starts with that one and it goes off, how it could influence the others to randomly trigger like that. Wouldn't that mean they all have issues?
>
> > > >
>
> > > > --- In Simmons_Drums@yahoogroups.com, "gordonjcp" <gordon@> wrote:
>
> > > > >
>
> > > > >
>
> > > > > > If the mux/demux caps are worn out and ALL the caps are the same age on the board, wouldn't it make sense to change them all? They are cheap enough.
>
> > > > >
>
> > > > > They don't wear out. They rarely fail. When they do, they cause very, very distinctive faults.
>
> > > > >
>
> > > > > It's worth noting that just about the only capacitors I have ever seen fail have been electrolytics used in cheap crappy switched-mode power supplies (which you don't have here) and disc ceramics used at high voltage or in RF amps. In synthesizers I've changed maybe a dozen genuinely faulty capacitors in 20-odd years.
>
> > > > >
>
> > > > > Capacitors don't fail, and they don't wear out.
>
> > > > >
>
> > > > > > As I stated previously, that didn't change the issue I'm having with it, so now it has to be the mux/demux ICs, as stated earlier in this thread by Michael himself on the issue with this machine that this member is having.
>
> > > > >
>
> > > > > Of course it didn't, and now you've got to do what you should have done to begin with - diagnose the fault! The 405x family multiplexers do fail, with either an output getting "stuck" usually to one supply rail or the other, or the inputs just not switching at all. Get an oscilloscope, track down the fault, and replace just the part that has failed.
>
> > > > >
>
> > > > > > If I've replaced all the caps with the proper values and it does the exact same thing it did before, how then could I have created more problems? Can you please explain that theory?
>
> > > > >
>
> > > > > How good is your soldering? Are you sure you read all those capacitors correctly? Are you sure you didn't damage the fragile through-hole plating on the boards? Are you sure you didn't zap something with static?
>
> > > > >
>
> > > > > I won't touch *anything* that's been "re-capped". I often see synths that have been "re-capped" by some Expert Synth Doctor that then never quite works right again, and then they're just too much bother to put right.
>
> > > > >
>
> > > > > Don't muck about. Track the fault down and fix *just that fault*.
>
> > > > >
>
> > > > > --
>
> > > > > Gordonjcp MM0YEQ
>
> > > > >
>
> > > >
>
> > >
>
> >
>
>
> [Non-text portions of this message have been removed]
>
>
>
>
>
> [Non-text portions of this message have been removed]
>

I like Michael have repaired quite a few SDS9's in my time and fully agree with what he is saying. 95% of the random triggering issues I have dealt with were the result of a faulty 4051's the others were due to faulty address decoders (IC's 58 and 61) or dud bypass caps associated with the demux circuit (creating noise spikes)

Here is my take... Replace (ic socket fitted at same time) IC19,IC64,65,66,67 and 68. Replace ALL 100nf decoupling caps for these IC's also (you have already done this I see) The parts are cheap and once this has been done you will know for certain that the demux section can be ruled out. We can then go from that point to narrow down the fault.

As to recapping...well that is a subject that stirs up a hornets nest every time it is mentioned. To state that capacitors "wear out" is a bit of a false statement. They simply don't. BUT there are types that can and will deteriorate over time to a point that they no longer function as a capacitor (acting more like a resistor or going dead short) or there rated value at time of manufacture is way out.

Ceramics, mylars and the like are generally quite robust and don't need replacing (unless they have been stressed beyond ratings due to PSU fault or similar)
Tantalum caps usually fail dramatically releasing magic smoke in the process. They are notorious for failing and in any "vintage" gear I replace them...THEY WILL FAIL< IT"S JUST A MATTER OF TIME.
Electrolytics also fail on a regular basis. The electrolyte dries out over time causing drift of value and voltage piercing through between the plates (dead short)

I speak from experience, 35 yrs as an electronics engineer and technician working with gear from the simplest up to highly accurate and sensitive lab gear in universities. I can say without exception any equipment I have recapped has benefited greatly from the work carried out. Gear that once was way out of spec would become usable once again. Yes the process of electronic repair can insert new faults, but in due care is taken during the process this is minimized. It's not rocket science but a bit of knowledge and understanding certainly goes a long way.

Richard


In Simmons_Drums@yahoogroups.com, "Michael Buchner" <buchnerelectronics@...> wrote:

>
> Start with the 4051s. In most cases...
>
> Best
>
> Michael
>

If not obvious: Cut the legs of the ICs to be replaced with a pair of
pliars and desolder one leg at a time. Removing an entire IC without
destroying it is a pain and only worth the effort if we're talking CEMs,
SSMs and similar rarities...

--
electronically yours, jesper

- -- --- ---- ----- ---- --- -- -
www.electronic-obsession.se

simmonssds7fan skrev 2013-05-22 16:47:

> I can tell you from personal experience that it took the better part of
> two afternoons to de-solder the old caps and solder in the new ones (but
> as I stated before I replaced all 100 caps that were of the same value
> on the board, probably overkill, but since I was there....) I can only
> imagine how long it will take to replace the six 4051 chips and the one
> other that controlls them (16 pins each chip). Michael mentioned
> possible replacement of all the tl84 chips as well, which I believe
> there are 20 sum such of them on the board (14 pins each).
>
> --- In Simmons_Drums@yahoogroups.com
> <mailto:Simmons_Drums%40yahoogroups.com>, Jacquot.Patrice@... wrote:
> >
> > I guess I will confirm you that suspicions quite soon , as my both 9
> are asthmatic at the moment ;)
> > funny enough at the same moment actually.
> >
> > Michael is it a lot of time consuming that Demux stuff to check &
> change ?
> >
> > thx for your precious advice.
> >
> >
> > ----- Mail d'origine -----
> > De: Michael Buchner <buchnerelectronics@...>
> > À: Simmons Drums <Simmons_Drums@yahoogroups.com
> <mailto:Simmons_Drums%40yahoogroups.com>>
> > Envoyé: Wed, 22 May 2013 14:34:32 +0200 (CEST)
> > Objet: Re: [Simmons Drums] Re: SDS 9 elementary problem & deeper fault
> >
> >
> >
> >
> >
> > I had nearly 30 SDS9 in my shop for repair, in nearly all cases the
> fault was the demux. I repaired some SDS9 by changing the s/h caps, some
> by replacing the demux chips. To be honest: The last few times I cut out
> all these demux responsible parts (4051, TL 84 and the caps) at once and
> renewed everything, I saved a lot of time (testing and thinking) and the
> parts were not expensive.
> >
> >
> > The demux is built up like a matrix, meaning that one single demux
> chip is responsible for (example) low tom trigger, snare filter
> frequency, mid tom pitch a.s.o. I sent you the (brilliant) schematics of
> Thierry EPPHERRE, so you can see this there. It is NOT one demux chip
> responsible for ONE instrument.
> >
> >
> > If you touch the legs of the demux chips, while the unit is running,
> you should hear something changing, stopping or getting better or worse.
> You can apply pressure with your thumb and finger like you would want to
> pull the chip out. As long as you don't lick, your skin resistance is
> big enough that nothing can be damaged.
> >
> >
> > Good luck, and I bet 10 bucks on a faulty demux.
> >
> >
> > Michael
> >
> >
> > The "lick" test is ok, without licking.
> >
> > ----- Original Message -----
> >
> > From: simmonssds7fan
> >
> > To: Simmons_Drums@yahoogroups.com
> <mailto:Simmons_Drums%40yahoogroups.com>
> >
> > Sent: Wednesday, May 22, 2013 11:57 AM
> >
> > Subject: [Simmons Drums] Re: SDS 9 elementary problem & deeper fault
> >
> >
> > Sorry, the cap value should have read 100nf-63v, or .1uf-63v, NOT
> .1nf it is early here...LOL!
> >
> >
> > --- In Simmons_Drums@yahoogroups.com
> <mailto:Simmons_Drums%40yahoogroups.com>, "simmonssds7fan" <ptmetcalf@>
> wrote:
> >
> > >
> >
> > > I replaced all the polyfilm caps that were rated at .1nf-63v on the
> board as I was told that these were "worn out and at the end of their
> useful life". I was also told that it was the ones in the mux/demux
> circuits that would be faulty specifically, that those are "usually the
> problem". It was my decision to replace all of them on the board of this
> value since I figured, if the mux/demux ones are worn out and they are
> all the same age, then it made sense to replace them all.
> >
> > > I'm in the USA and the power transformer is wired up to run at 115V.
> >
> > > The erpom chip I used for the 3.0 OS is of the same type as the
> original. It is an Intel 27128a chip. I bought a bought a bunch of NOS
> ones a while ago for extra sound proms for my sds7 and tested them all a
> while ago, and yes I did use a prom eraser to make sure it was good to
> go. Also, I do have a good prommer and know how to use it. I'm sure it's
> not in the OS EPROM since the unit does the same thing with the 3.0 as
> the 4.0 OS that was installed in it when I first got the machine.
> >
> > >
> >
> > > I will try the "lick test" next......we'll see what happens next I
> guess...
> >
> > >
> >
> > > --- In Simmons_Drums@yahoogroups.com
> <mailto:Simmons_Drums%40yahoogroups.com>, "philmurr" <philmurr@> wrote:
> >
> > > >
> >
> > > > I'm from the "replace electrolytics caps" school. Especially the
> power supply section. I can't remember for sure, but think there are
> only half a dozen electrolytics on the board, and none of them doing
> anything "critical".
> >
> > > >
> >
> > > > It's not unusual for an SDS9 to run hot (underneath) as that's
> where the PSU board is connected. Where in the world are you, and what
> is your mains voltage, as the transformer is multi-tapped and the unit
> will run quite happily on a higher tap, unless you're in the UK in which
> case you've got no choice :(.
> >
> > > >
> >
> > > > With the box running and doing the random triggering, lick your
> finger and touch the top of all chips, see if any dry out quickly, an
> indication of them running hot.
> >
> > > >
> >
> > > > Are you sure the ROM chip you replaced is fast enough (and is the
> RAM original for the same reason?)
> >
> > > >
> >
> > > > Can you also check the +5V at various points on the board (esp.
> furthest away from where the power connector is). On one of mine I
> connected a 100uF or similar near the CPU chip just to help the power
> supply out and it stopped it doing odd things.
> >
> > > >
> >
> > > > From memory, and I haven't checked the service manual recently, I
> recall there is a "full-on" test mode that you can put the unit into,
> can anyone else confirm ?
> >
> > > >
> >
> > > > Phil.
> >
> > > >
> >
> > > > --- In Simmons_Drums@yahoogroups.com
> <mailto:Simmons_Drums%40yahoogroups.com>, "simmonssds7fan" <ptmetcalf@>
> wrote:
> >
> > > > >
> >
> > > > > Alright then.....let me run the issue by you then and see what
> you think it is.
> >
> > > > >
> >
> > > > > When you power it up, it initializes normally. Then the low tom
> circuit trigger led comes on and sound is faintly generated, sounds like
> a constant "doom-doom-doom", then it slowly stops. After the low tom
> stops any one of the other toms or snare will trigger randomly at full
> volume until they are all triggering at the same time, generating a
> buzz/white noise. The bass channel never does this, only the snare/rim,
> and the toms. The unit gets rather warm when it does this. If you shut
> it off and let it sit until it gets back to room temperature, it goes
> back to near normal and the cycle repeats. I have changed the OS chip to
> the 3.0 version, it did have the 4.0 version, but it only slightly helped.
> >
> > > > >
> >
> > > > > Any ideas which mux/demux chip I should start with? I'm
> thinking the low tom, but I don't understand if it starts with that one
> and it goes off, how it could influence the others to randomly trigger
> like that. Wouldn't that mean they all have issues?
> >
> > > > >
> >
> > > > > --- In Simmons_Drums@yahoogroups.com
> <mailto:Simmons_Drums%40yahoogroups.com>, "gordonjcp" <gordon@> wrote:
> >
> > > > > >
> >
> > > > > >
> >
> > > > > > > If the mux/demux caps are worn out and ALL the caps are the
> same age on the board, wouldn't it make sense to change them all? They
> are cheap enough.
> >
> > > > > >
> >
> > > > > > They don't wear out. They rarely fail. When they do, they
> cause very, very distinctive faults.
> >
> > > > > >
> >
> > > > > > It's worth noting that just about the only capacitors I have
> ever seen fail have been electrolytics used in cheap crappy
> switched-mode power supplies (which you don't have here) and disc
> ceramics used at high voltage or in RF amps. In synthesizers I've
> changed maybe a dozen genuinely faulty capacitors in 20-odd years.
> >
> > > > > >
> >
> > > > > > Capacitors don't fail, and they don't wear out.
> >
> > > > > >
> >
> > > > > > > As I stated previously, that didn't change the issue I'm
> having with it, so now it has to be the mux/demux ICs, as stated earlier
> in this thread by Michael himself on the issue with this machine that
> this member is having.
> >
> > > > > >
> >
> > > > > > Of course it didn't, and now you've got to do what you should
> have done to begin with - diagnose the fault! The 405x family
> multiplexers do fail, with either an output getting "stuck" usually to
> one supply rail or the other, or the inputs just not switching at all.
> Get an oscilloscope, track down the fault, and replace just the part
> that has failed.
> >
> > > > > >
> >
> > > > > > > If I've replaced all the caps with the proper values and it
> does the exact same thing it did before, how then could I have created
> more problems? Can you please explain that theory?
> >
> > > > > >
> >
> > > > > > How good is your soldering? Are you sure you read all those
> capacitors correctly? Are you sure you didn't damage the fragile
> through-hole plating on the boards? Are you sure you didn't zap
> something with static?
> >
> > > > > >
> >
> > > > > > I won't touch *anything* that's been "re-capped". I often see
> synths that have been "re-capped" by some Expert Synth Doctor that then
> never quite works right again, and then they're just too much bother to
> put right.
> >
> > > > > >
> >
> > > > > > Don't muck about. Track the fault down and fix *just that fault*.
> >
> > > > > >
> >
> > > > > > --
> >
> > > > > > Gordonjcp MM0YEQ
> >
> > > > > >
> >
> > > > >
> >
> > > >
> >
> > >
> >
> >
> > [Non-text portions of this message have been removed]
> >
> >
> >
> >
> >
> > [Non-text portions of this message have been removed]
> >
>
>
>
> No virus found in this message.
> Checked by AVG - www.avg.com <http://www.avg.com>
> Version: 2012.0.2242 / Virus Database: 3162/5848 - Release Date: 05/22/13
>

--
electronically yours, jesper

- -- --- ---- ----- ---- --- -- -
www.electronic-obsession.se

It takes some time. To change an IC, you can say: half an hour.
I cut the IC legs on the component side with a dremel disc, so that the IC body falls off. The legs remain in the PCB. After that, I desolder one leg after the other and clean the solder eyes on the PCB with a desoldering pump. Now the area looks like new.
This method has many advantages: You don't need to apply force, so nothing can break or soldering eyes lift from the PCB. You don't need to apply much heat too. It is a double-sided PCB and you can destroy tracks, if you, for example, shovel with a screwdriver under an IC to lift it.

Good luck

----- Original Message -----
From: Jacquot.Patrice@...
To: Simmons Drums
Sent: Wednesday, May 22, 2013 4:24 PM
Subject: Re : Re: [Simmons Drums] Re: SDS 9 elementary problem & deeper fault



I guess I will confirm you that suspicions quite soon , as my both 9 are asthmatic at the moment ;)
funny enough at the same moment actually.

Michael is it a lot of time consuming that Demux stuff to check & change ?

thx for your precious advice.

----- Mail d'origine -----
De: Michael Buchner <buchnerelectronics@...>
À: Simmons Drums <Simmons_Drums@yahoogroups.com>
Envoyé: Wed, 22 May 2013 14:34:32 +0200 (CEST)
Objet: Re: [Simmons Drums] Re: SDS 9 elementary problem & deeper fault

I had nearly 30 SDS9 in my shop for repair, in nearly all cases the fault was the demux. I repaired some SDS9 by changing the s/h caps, some by replacing the demux chips. To be honest: The last few times I cut out all these demux responsible parts (4051, TL 84 and the caps) at once and renewed everything, I saved a lot of time (testing and thinking) and the parts were not expensive.

The demux is built up like a matrix, meaning that one single demux chip is responsible for (example) low tom trigger, snare filter frequency, mid tom pitch a.s.o. I sent you the (brilliant) schematics of Thierry EPPHERRE, so you can see this there. It is NOT one demux chip responsible for ONE instrument.

If you touch the legs of the demux chips, while the unit is running, you should hear something changing, stopping or getting better or worse. You can apply pressure with your thumb and finger like you would want to pull the chip out. As long as you don't lick, your skin resistance is big enough that nothing can be damaged.

Good luck, and I bet 10 bucks on a faulty demux.

Michael

The "lick" test is ok, without licking.

----- Original Message -----

From: simmonssds7fan

To: Simmons_Drums@yahoogroups.com

Sent: Wednesday, May 22, 2013 11:57 AM

Subject: [Simmons Drums] Re: SDS 9 elementary problem & deeper fault

Sorry, the cap value should have read 100nf-63v, or .1uf-63v, NOT .1nf it is early here...LOL!

--- In Simmons_Drums@yahoogroups.com, "simmonssds7fan" <ptmetcalf@...> wrote:

>

> I replaced all the polyfilm caps that were rated at .1nf-63v on the board as I was told that these were "worn out and at the end of their useful life". I was also told that it was the ones in the mux/demux circuits that would be faulty specifically, that those are "usually the problem". It was my decision to replace all of them on the board of this value since I figured, if the mux/demux ones are worn out and they are all the same age, then it made sense to replace them all.

> I'm in the USA and the power transformer is wired up to run at 115V.

> The erpom chip I used for the 3.0 OS is of the same type as the original. It is an Intel 27128a chip. I bought a bought a bunch of NOS ones a while ago for extra sound proms for my sds7 and tested them all a while ago, and yes I did use a prom eraser to make sure it was good to go. Also, I do have a good prommer and know how to use it. I'm sure it's not in the OS EPROM since the unit does the same thing with the 3.0 as the 4.0 OS that was installed in it when I first got the machine.

>

> I will try the "lick test" next......we'll see what happens next I guess...

>

> --- In Simmons_Drums@yahoogroups.com, "philmurr" <philmurr@> wrote:

> >

> > I'm from the "replace electrolytics caps" school. Especially the power supply section. I can't remember for sure, but think there are only half a dozen electrolytics on the board, and none of them doing anything "critical".

> >

> > It's not unusual for an SDS9 to run hot (underneath) as that's where the PSU board is connected. Where in the world are you, and what is your mains voltage, as the transformer is multi-tapped and the unit will run quite happily on a higher tap, unless you're in the UK in which case you've got no choice :(.

> >

> > With the box running and doing the random triggering, lick your finger and touch the top of all chips, see if any dry out quickly, an indication of them running hot.

> >

> > Are you sure the ROM chip you replaced is fast enough (and is the RAM original for the same reason?)

> >

> > Can you also check the +5V at various points on the board (esp. furthest away from where the power connector is). On one of mine I connected a 100uF or similar near the CPU chip just to help the power supply out and it stopped it doing odd things.

> >

> > From memory, and I haven't checked the service manual recently, I recall there is a "full-on" test mode that you can put the unit into, can anyone else confirm ?

> >

> > Phil.

> >

> > --- In Simmons_Drums@yahoogroups.com, "simmonssds7fan" <ptmetcalf@> wrote:

> > >

> > > Alright then.....let me run the issue by you then and see what you think it is.

> > >

> > > When you power it up, it initializes normally. Then the low tom circuit trigger led comes on and sound is faintly generated, sounds like a constant "doom-doom-doom", then it slowly stops. After the low tom stops any one of the other toms or snare will trigger randomly at full volume until they are all triggering at the same time, generating a buzz/white noise. The bass channel never does this, only the snare/rim, and the toms. The unit gets rather warm when it does this. If you shut it off and let it sit until it gets back to room temperature, it goes back to near normal and the cycle repeats. I have changed the OS chip to the 3.0 version, it did have the 4.0 version, but it only slightly helped.

> > >

> > > Any ideas which mux/demux chip I should start with? I'm thinking the low tom, but I don't understand if it starts with that one and it goes off, how it could influence the others to randomly trigger like that. Wouldn't that mean they all have issues?

> > >

> > > --- In Simmons_Drums@yahoogroups.com, "gordonjcp" <gordon@> wrote:

> > > >

> > > >

> > > > > If the mux/demux caps are worn out and ALL the caps are the same age on the board, wouldn't it make sense to change them all? They are cheap enough.

> > > >

> > > > They don't wear out. They rarely fail. When they do, they cause very, very distinctive faults.

> > > >

> > > > It's worth noting that just about the only capacitors I have ever seen fail have been electrolytics used in cheap crappy switched-mode power supplies (which you don't have here) and disc ceramics used at high voltage or in RF amps. In synthesizers I've changed maybe a dozen genuinely faulty capacitors in 20-odd years.

> > > >

> > > > Capacitors don't fail, and they don't wear out.

> > > >

> > > > > As I stated previously, that didn't change the issue I'm having with it, so now it has to be the mux/demux ICs, as stated earlier in this thread by Michael himself on the issue with this machine that this member is having.

> > > >

> > > > Of course it didn't, and now you've got to do what you should have done to begin with - diagnose the fault! The 405x family multiplexers do fail, with either an output getting "stuck" usually to one supply rail or the other, or the inputs just not switching at all. Get an oscilloscope, track down the fault, and replace just the part that has failed.

> > > >

> > > > > If I've replaced all the caps with the proper values and it does the exact same thing it did before, how then could I have created more problems? Can you please explain that theory?

> > > >

> > > > How good is your soldering? Are you sure you read all those capacitors correctly? Are you sure you didn't damage the fragile through-hole plating on the boards? Are you sure you didn't zap something with static?

> > > >

> > > > I won't touch *anything* that's been "re-capped". I often see synths that have been "re-capped" by some Expert Synth Doctor that then never quite works right again, and then they're just too much bother to put right.

> > > >

> > > > Don't muck about. Track the fault down and fix *just that fault*.

> > > >

> > > > --

> > > > Gordonjcp MM0YEQ

> > > >

> > >

> >

>

[Non-text portions of this message have been removed]

[Non-text portions of this message have been removed]





[Non-text portions of this message have been removed]

In some cases, a re-capping is recommended. There are different brands of capacitors reacting different to humidity. On some SDSVs I had the chewing gum like types, where the edges fell off by a slightly touch. This was an indicator to change all immediatelly. On other SDSVs they had these grey plastic capacitors with no damage at all, so I left all of them as they were.
On a faulty SDX I had a broken down (and burnt) 15V regulator and I found the fault: A shortcut by an exploded tantalum blocking capacitor. In this case I changed all of them too.
One certain brand looses its legs by oxidation, if I see one of these, I replace it.
So: Pros and cons, like always

----- Original Message -----
From: Richard
To: Simmons_Drums@yahoogroups.com
Sent: Wednesday, May 22, 2013 5:57 PM
Subject: [Simmons Drums] Re: SDS 9 elementary problem & deeper fault



I like Michael have repaired quite a few SDS9's in my time and fully agree with what he is saying. 95% of the random triggering issues I have dealt with were the result of a faulty 4051's the others were due to faulty address decoders (IC's 58 and 61) or dud bypass caps associated with the demux circuit (creating noise spikes)

Here is my take... Replace (ic socket fitted at same time) IC19,IC64,65,66,67 and 68. Replace ALL 100nf decoupling caps for these IC's also (you have already done this I see) The parts are cheap and once this has been done you will know for certain that the demux section can be ruled out. We can then go from that point to narrow down the fault.

As to recapping...well that is a subject that stirs up a hornets nest every time it is mentioned. To state that capacitors "wear out" is a bit of a false statement. They simply don't. BUT there are types that can and will deteriorate over time to a point that they no longer function as a capacitor (acting more like a resistor or going dead short) or there rated value at time of manufacture is way out.

Ceramics, mylars and the like are generally quite robust and don't need replacing (unless they have been stressed beyond ratings due to PSU fault or similar)
Tantalum caps usually fail dramatically releasing magic smoke in the process. They are notorious for failing and in any "vintage" gear I replace them...THEY WILL FAIL< IT"S JUST A MATTER OF TIME.
Electrolytics also fail on a regular basis. The electrolyte dries out over time causing drift of value and voltage piercing through between the plates (dead short)

I speak from experience, 35 yrs as an electronics engineer and technician working with gear from the simplest up to highly accurate and sensitive lab gear in universities. I can say without exception any equipment I have recapped has benefited greatly from the work carried out. Gear that once was way out of spec would become usable once again. Yes the process of electronic repair can insert new faults, but in due care is taken during the process this is minimized. It's not rocket science but a bit of knowledge and understanding certainly goes a long way.

Richard

In Simmons_Drums@yahoogroups.com, "Michael Buchner" <buchnerelectronics@...> wrote:
>
> Start with the 4051s. In most cases...
>
> Best
>
> Michael
>





[Non-text portions of this message have been removed]

I should have the replacement 4051s here today, so this may be a nice starting point on this project for the weekend. I ordered some tl84s as a precaution (they were cheap) just in case the 4051s aren't the entire problem. I also ordered a replacement IC for IC61 and am planning on changing that one out as well as the six 4051s. I didn't think of changing IC58, but if replacing these seven IC's doesn't change much, I may get one of those and change that one out before changing all the tl84's. I'm jumping the gun a bit I suppose, but I need to have some kind of game-plan right?

Thanks to everyone with helpful insight to the workings and faults to these SDS-9 units, it is much appreciated. I'll keep everyone up to speed with what happens after the 4051 replacement.

--- In Simmons_Drums@yahoogroups.com, "Richard" <warlandr63@...> wrote:
>
> I like Michael have repaired quite a few SDS9's in my time and fully agree with what he is saying. 95% of the random triggering issues I have dealt with were the result of a faulty 4051's the others were due to faulty address decoders (IC's 58 and 61) or dud bypass caps associated with the demux circuit (creating noise spikes)
>
> Here is my take... Replace (ic socket fitted at same time) IC19,IC64,65,66,67 and 68. Replace ALL 100nf decoupling caps for these IC's also (you have already done this I see) The parts are cheap and once this has been done you will know for certain that the demux section can be ruled out. We can then go from that point to narrow down the fault.
>
> As to recapping...well that is a subject that stirs up a hornets nest every time it is mentioned. To state that capacitors "wear out" is a bit of a false statement. They simply don't. BUT there are types that can and will deteriorate over time to a point that they no longer function as a capacitor (acting more like a resistor or going dead short) or there rated value at time of manufacture is way out.
>
> Ceramics, mylars and the like are generally quite robust and don't need replacing (unless they have been stressed beyond ratings due to PSU fault or similar)
> Tantalum caps usually fail dramatically releasing magic smoke in the process. They are notorious for failing and in any "vintage" gear I replace them...THEY WILL FAIL< IT"S JUST A MATTER OF TIME.
> Electrolytics also fail on a regular basis. The electrolyte dries out over time causing drift of value and voltage piercing through between the plates (dead short)
>
> I speak from experience, 35 yrs as an electronics engineer and technician working with gear from the simplest up to highly accurate and sensitive lab gear in universities. I can say without exception any equipment I have recapped has benefited greatly from the work carried out. Gear that once was way out of spec would become usable once again. Yes the process of electronic repair can insert new faults, but in due care is taken during the process this is minimized. It's not rocket science but a bit of knowledge and understanding certainly goes a long way.
>
> Richard
>
>
> In Simmons_Drums@yahoogroups.com, "Michael Buchner" <buchnerelectronics@> wrote:
> >
> > Start with the 4051s. In most cases...
> >
> > Best
> >
> > Michael
> >
>

Progress report: replaced IC61 and the six 4051 demux chips, no real change other than the sound generation is a bit stronger. The original random triggering issue is still there. The TL084 chips arrive tomorrow. I'll see what transpires after the replacement of those. Starting to lean towards IC58 being the problem, but I guess it won't hurt to replace those TL084s either.....

--- In Simmons_Drums@yahoogroups.com, "simmonssds7fan" <ptmetcalf@...> wrote:
>
> I should have the replacement 4051s here today, so this may be a nice starting point on this project for the weekend. I ordered some tl84s as a precaution (they were cheap) just in case the 4051s aren't the entire problem. I also ordered a replacement IC for IC61 and am planning on changing that one out as well as the six 4051s. I didn't think of changing IC58, but if replacing these seven IC's doesn't change much, I may get one of those and change that one out before changing all the tl84's. I'm jumping the gun a bit I suppose, but I need to have some kind of game-plan right?
>
> Thanks to everyone with helpful insight to the workings and faults to these SDS-9 units, it is much appreciated. I'll keep everyone up to speed with what happens after the 4051 replacement.
>
> --- In Simmons_Drums@yahoogroups.com, "Richard" <warlandr63@> wrote:
> >
> > I like Michael have repaired quite a few SDS9's in my time and fully agree with what he is saying. 95% of the random triggering issues I have dealt with were the result of a faulty 4051's the others were due to faulty address decoders (IC's 58 and 61) or dud bypass caps associated with the demux circuit (creating noise spikes)
> >
> > Here is my take... Replace (ic socket fitted at same time) IC19,IC64,65,66,67 and 68. Replace ALL 100nf decoupling caps for these IC's also (you have already done this I see) The parts are cheap and once this has been done you will know for certain that the demux section can be ruled out. We can then go from that point to narrow down the fault.
> >
> > As to recapping...well that is a subject that stirs up a hornets nest every time it is mentioned. To state that capacitors "wear out" is a bit of a false statement. They simply don't. BUT there are types that can and will deteriorate over time to a point that they no longer function as a capacitor (acting more like a resistor or going dead short) or there rated value at time of manufacture is way out.
> >
> > Ceramics, mylars and the like are generally quite robust and don't need replacing (unless they have been stressed beyond ratings due to PSU fault or similar)
> > Tantalum caps usually fail dramatically releasing magic smoke in the process. They are notorious for failing and in any "vintage" gear I replace them...THEY WILL FAIL< IT"S JUST A MATTER OF TIME.
> > Electrolytics also fail on a regular basis. The electrolyte dries out over time causing drift of value and voltage piercing through between the plates (dead short)
> >
> > I speak from experience, 35 yrs as an electronics engineer and technician working with gear from the simplest up to highly accurate and sensitive lab gear in universities. I can say without exception any equipment I have recapped has benefited greatly from the work carried out. Gear that once was way out of spec would become usable once again. Yes the process of electronic repair can insert new faults, but in due care is taken during the process this is minimized. It's not rocket science but a bit of knowledge and understanding certainly goes a long way.
> >
> > Richard
> >
> >
> > In Simmons_Drums@yahoogroups.com, "Michael Buchner" <buchnerelectronics@> wrote:
> > >
> > > Start with the 4051s. In most cases...
> > >
> > > Best
> > >
> > > Michael
> > >
> >
>

--- In Simmons_Drums@yahoogroups.com, "simmonssds7fan" <ptmetcalf@...> wrote:

>
> Progress report: replaced IC61 and the six 4051 demux chips, no real change other than the sound generation is a bit stronger. The original random triggering issue is still there. The TL084 chips arrive tomorrow. I'll see what transpires after the replacement of those. Starting to lean towards IC58 being the problem, but I guess it won't hurt to replace those TL084s either.....
>

Yes, it can hurt to replace those TL084s. Are you just randomly replacing bits one at a time and hoping you get lucky?

*TEST* - then, if the part is faulty replace it. Don't just charge in and start ripping parts out hoping that this one, maybe, might just be the faulty one.

--
Gordonjcp MM0YEQ

Progress report number two, one night later: I'm closer than I was last evening with getting my SDS9 fixed. Thought I had it tonight after replacing all 17 TL084N chips (a tedious job I might ad). Started off like it was fixed and then after a bit....the random triggering started again. On the plus side of things the constant "dooming" from the low tom channel has stopped. It now triggers normally with the pad input as well as randomly when it starts acting up, so its not non-functioning, its just randomly functioning like the others. So, now that I've eliminated the 4051 chips, the tl084 chips and IC61, it has to be IC58 causing this. I have that on order and should see it Tuesday after the Memorial Day holiday (here in the USA). This is the next step. If that doesn't cure it, I suspect that IC50 in the input mux side of things may possibly have an issue as everything seems to run through that first, then on to the rest of the mux/demux circuits.

So close, yet so far.

And Gordon, I do understand what you are saying about test first, then replace. However, I do NOT own an oscilloscope, and the factory service manual is only schematics, no test procedures for the various ICs. I've been using the schematics supplied by Michael Buchner to me that are far superior to the factory ones and this has been a major asset. I am NOT a professional electronics repair tech by any means, but I do have a basic understanding of what the various electronic components are supposed to do and have limited schematics reading ability. Fortunately my soldering skills are much better than my "diagnosing" skills. This is why I've been asking advice here to help point me in the right direction. It may seem to some that I'm just randomly replacing parts, but I am going on the theory that these components are nearly 30 years old and are near the end, if not already at, the end of their life and should be replaced anyway in order to make it function correctly again. I have been going in stages as suggested by others here, and as it is, I'm having progress. Limited as it may be, but it is still progress. I am closer to it being fixed more tonight, than any time in the past. Recapping it helped the sound AFTER I replaced the mux/demux 4051 ICs and IC61. The sound quality is even better after replacing the mux/demux tl084 ICs, and it has resolved a couple of the issues I was having, but not all.

Again, thanks to those who have helped here by steering me in the right direction, especially Michael for the great schematics and advice.

--- In Simmons_Drums@yahoogroups.com, "simmonssds7fan" <ptmetcalf@...> wrote:
>
> Progress report: replaced IC61 and the six 4051 demux chips, no real change other than the sound generation is a bit stronger. The original random triggering issue is still there. The TL084 chips arrive tomorrow. I'll see what transpires after the replacement of those. Starting to lean towards IC58 being the problem, but I guess it won't hurt to replace those TL084s either.....
>
> --- In Simmons_Drums@yahoogroups.com, "simmonssds7fan" <ptmetcalf@> wrote:
> >
> > I should have the replacement 4051s here today, so this may be a nice starting point on this project for the weekend. I ordered some tl84s as a precaution (they were cheap) just in case the 4051s aren't the entire problem. I also ordered a replacement IC for IC61 and am planning on changing that one out as well as the six 4051s. I didn't think of changing IC58, but if replacing these seven IC's doesn't change much, I may get one of those and change that one out before changing all the tl84's. I'm jumping the gun a bit I suppose, but I need to have some kind of game-plan right?
> >
> > Thanks to everyone with helpful insight to the workings and faults to these SDS-9 units, it is much appreciated. I'll keep everyone up to speed with what happens after the 4051 replacement.
> >
> > --- In Simmons_Drums@yahoogroups.com, "Richard" <warlandr63@> wrote:
> > >
> > > I like Michael have repaired quite a few SDS9's in my time and fully agree with what he is saying. 95% of the random triggering issues I have dealt with were the result of a faulty 4051's the others were due to faulty address decoders (IC's 58 and 61) or dud bypass caps associated with the demux circuit (creating noise spikes)
> > >
> > > Here is my take... Replace (ic socket fitted at same time) IC19,IC64,65,66,67 and 68. Replace ALL 100nf decoupling caps for these IC's also (you have already done this I see) The parts are cheap and once this has been done you will know for certain that the demux section can be ruled out. We can then go from that point to narrow down the fault.
> > >
> > > As to recapping...well that is a subject that stirs up a hornets nest every time it is mentioned. To state that capacitors "wear out" is a bit of a false statement. They simply don't. BUT there are types that can and will deteriorate over time to a point that they no longer function as a capacitor (acting more like a resistor or going dead short) or there rated value at time of manufacture is way out.
> > >
> > > Ceramics, mylars and the like are generally quite robust and don't need replacing (unless they have been stressed beyond ratings due to PSU fault or similar)
> > > Tantalum caps usually fail dramatically releasing magic smoke in the process. They are notorious for failing and in any "vintage" gear I replace them...THEY WILL FAIL< IT"S JUST A MATTER OF TIME.
> > > Electrolytics also fail on a regular basis. The electrolyte dries out over time causing drift of value and voltage piercing through between the plates (dead short)
> > >
> > > I speak from experience, 35 yrs as an electronics engineer and technician working with gear from the simplest up to highly accurate and sensitive lab gear in universities. I can say without exception any equipment I have recapped has benefited greatly from the work carried out. Gear that once was way out of spec would become usable once again. Yes the process of electronic repair can insert new faults, but in due care is taken during the process this is minimized. It's not rocket science but a bit of knowledge and understanding certainly goes a long way.
> > >
> > > Richard
> > >
> > >
> > > In Simmons_Drums@yahoogroups.com, "Michael Buchner" <buchnerelectronics@> wrote:
> > > >
> > > > Start with the 4051s. In most cases...
> > > >
> > > > Best
> > > >
> > > > Michael
> > > >
> > >
> >
>

Yes you are correct that the correct path to go is to properly test and identify the fault, seek out the cause then rectify that cause. This is all good in a perfect world where the person attempting the repair has ALL the required test equipment required to carry out proper fault diagnosis. In this case I am assuming the original poster may not have access to such test equipment thus is seeking direction from those who may have had experience in such repairs. The suggestion to simply replace the mux components won't identify the fault nor it's cause yet if it worked then we have one happy SDS user.
My experience with the SDS9 showing such symptoms was faulty 4051's in the mux. I myself don't see that one faulty TL084 will cause the unit to behave the way it is.

I have had one unit display the random triggering problem that required the use of a logic analyzer hooked to the address ,data buss and chip select lines to diagnose what was going on. To be fair I don't think too many people have that sort of kit. Yes it's all in a days work for ppl like myself but I have spent years in the business and accumulated some very expensive test gear over time. Lets give the guy a break and do what we can to help him (or her) out as best we can.

--- In Simmons_Drums@yahoogroups.com, "gordonjcp" <gordon@...> wrote:
>
>
>
> --- In Simmons_Drums@yahoogroups.com, "simmonssds7fan" <ptmetcalf@> wrote:
> >
> > Progress report: replaced IC61 and the six 4051 demux chips, no real change other than the sound generation is a bit stronger. The original random triggering issue is still there. The TL084 chips arrive tomorrow. I'll see what transpires after the replacement of those. Starting to lean towards IC58 being the problem, but I guess it won't hurt to replace those TL084s either.....
> >
>
> Yes, it can hurt to replace those TL084s. Are you just randomly replacing bits one at a time and hoping you get lucky?
>
> *TEST* - then, if the part is faulty replace it. Don't just charge in and start ripping parts out hoping that this one, maybe, might just be the faulty one.
>
> --
> Gordonjcp MM0YEQ
>

But: I lost my 10$, because it was not a 4051 fault!

----- Original Message -----
From: simmonssds7fan
To: Simmons_Drums@yahoogroups.com
Sent: Saturday, May 25, 2013 5:39 AM
Subject: [Simmons Drums] Re: SDS 9 elementary problem & deeper fault



Progress report number two, one night later: I'm closer than I was last evening with getting my SDS9 fixed. Thought I had it tonight after replacing all 17 TL084N chips (a tedious job I might ad). Started off like it was fixed and then after a bit....the random triggering started again. On the plus side of things the constant "dooming" from the low tom channel has stopped. It now triggers normally with the pad input as well as randomly when it starts acting up, so its not non-functioning, its just randomly functioning like the others. So, now that I've eliminated the 4051 chips, the tl084 chips and IC61, it has to be IC58 causing this. I have that on order and should see it Tuesday after the Memorial Day holiday (here in the USA). This is the next step. If that doesn't cure it, I suspect that IC50 in the input mux side of things may possibly have an issue as everything seems to run through that first, then on to the rest of the mux/demux circuits.

So close, yet so far.

And Gordon, I do understand what you are saying about test first, then replace. However, I do NOT own an oscilloscope, and the factory service manual is only schematics, no test procedures for the various ICs. I've been using the schematics supplied by Michael Buchner to me that are far superior to the factory ones and this has been a major asset. I am NOT a professional electronics repair tech by any means, but I do have a basic understanding of what the various electronic components are supposed to do and have limited schematics reading ability. Fortunately my soldering skills are much better than my "diagnosing" skills. This is why I've been asking advice here to help point me in the right direction. It may seem to some that I'm just randomly replacing parts, but I am going on the theory that these components are nearly 30 years old and are near the end, if not already at, the end of their life and should be replaced anyway in order to make it function correctly again. I have been going in stages as suggested by others here, and as it is, I'm having progress. Limited as it may be, but it is still progress. I am closer to it being fixed more tonight, than any time in the past. Recapping it helped the sound AFTER I replaced the mux/demux 4051 ICs and IC61. The sound quality is even better after replacing the mux/demux tl084 ICs, and it has resolved a couple of the issues I was having, but not all.

Again, thanks to those who have helped here by steering me in the right direction, especially Michael for the great schematics and advice.


--- In Simmons_Drums@yahoogroups.com, "simmonssds7fan" <ptmetcalf@...> wrote:
>
> Progress report: replaced IC61 and the six 4051 demux chips, no real change other than the sound generation is a bit stronger. The original random triggering issue is still there. The TL084 chips arrive tomorrow. I'll see what transpires after the replacement of those. Starting to lean towards IC58 being the problem, but I guess it won't hurt to replace those TL084s either.....
>
> --- In Simmons_Drums@yahoogroups.com, "simmonssds7fan" <ptmetcalf@> wrote:
> >
> > I should have the replacement 4051s here today, so this may be a nice starting point on this project for the weekend. I ordered some tl84s as a precaution (they were cheap) just in case the 4051s aren't the entire problem. I also ordered a replacement IC for IC61 and am planning on changing that one out as well as the six 4051s. I didn't think of changing IC58, but if replacing these seven IC's doesn't change much, I may get one of those and change that one out before changing all the tl84's. I'm jumping the gun a bit I suppose, but I need to have some kind of game-plan right?
> >
> > Thanks to everyone with helpful insight to the workings and faults to these SDS-9 units, it is much appreciated. I'll keep everyone up to speed with what happens after the 4051 replacement.
> >
> > --- In Simmons_Drums@yahoogroups.com, "Richard" <warlandr63@> wrote:
> > >
> > > I like Michael have repaired quite a few SDS9's in my time and fully agree with what he is saying. 95% of the random triggering issues I have dealt with were the result of a faulty 4051's the others were due to faulty address decoders (IC's 58 and 61) or dud bypass caps associated with the demux circuit (creating noise spikes)
> > >
> > > Here is my take... Replace (ic socket fitted at same time) IC19,IC64,65,66,67 and 68. Replace ALL 100nf decoupling caps for these IC's also (you have already done this I see) The parts are cheap and once this has been done you will know for certain that the demux section can be ruled out. We can then go from that point to narrow down the fault.
> > >
> > > As to recapping...well that is a subject that stirs up a hornets nest every time it is mentioned. To state that capacitors "wear out" is a bit of a false statement. They simply don't. BUT there are types that can and will deteriorate over time to a point that they no longer function as a capacitor (acting more like a resistor or going dead short) or there rated value at time of manufacture is way out.
> > >
> > > Ceramics, mylars and the like are generally quite robust and don't need replacing (unless they have been stressed beyond ratings due to PSU fault or similar)
> > > Tantalum caps usually fail dramatically releasing magic smoke in the process. They are notorious for failing and in any "vintage" gear I replace them...THEY WILL FAIL< IT"S JUST A MATTER OF TIME.
> > > Electrolytics also fail on a regular basis. The electrolyte dries out over time causing drift of value and voltage piercing through between the plates (dead short)
> > >
> > > I speak from experience, 35 yrs as an electronics engineer and technician working with gear from the simplest up to highly accurate and sensitive lab gear in universities. I can say without exception any equipment I have recapped has benefited greatly from the work carried out. Gear that once was way out of spec would become usable once again. Yes the process of electronic repair can insert new faults, but in due care is taken during the process this is minimized. It's not rocket science but a bit of knowledge and understanding certainly goes a long way.
> > >
> > > Richard
> > >
> > >
> > > In Simmons_Drums@yahoogroups.com, "Michael Buchner" <buchnerelectronics@> wrote:
> > > >
> > > > Start with the 4051s. In most cases...
> > > >
> > > > Best
> > > >
> > > > Michael
> > > >
> > >
> >
>





[Non-text portions of this message have been removed]

Haha! Got to love it Michael! I'd rather spend a little on components and have them fresh again and not have to worry about them for a while than the $10....LOL! Besides, I hate to admit what I paid for the thing in the first place. (Too much as it turns out since it wasn't working as described!)

~Paul

--- In Simmons_Drums@yahoogroups.com, "Michael Buchner" <buchnerelectronics@...> wrote:
>
> But: I lost my 10$, because it was not a 4051 fault!
>
>
>
> ----- Original Message -----
> From: simmonssds7fan
> To: Simmons_Drums@yahoogroups.com
> Sent: Saturday, May 25, 2013 5:39 AM
> Subject: [Simmons Drums] Re: SDS 9 elementary problem & deeper fault
>
>
>
> Progress report number two, one night later: I'm closer than I was last evening with getting my SDS9 fixed. Thought I had it tonight after replacing all 17 TL084N chips (a tedious job I might ad). Started off like it was fixed and then after a bit....the random triggering started again. On the plus side of things the constant "dooming" from the low tom channel has stopped. It now triggers normally with the pad input as well as randomly when it starts acting up, so its not non-functioning, its just randomly functioning like the others. So, now that I've eliminated the 4051 chips, the tl084 chips and IC61, it has to be IC58 causing this. I have that on order and should see it Tuesday after the Memorial Day holiday (here in the USA). This is the next step. If that doesn't cure it, I suspect that IC50 in the input mux side of things may possibly have an issue as everything seems to run through that first, then on to the rest of the mux/demux circuits.
>
> So close, yet so far.
>
> And Gordon, I do understand what you are saying about test first, then replace. However, I do NOT own an oscilloscope, and the factory service manual is only schematics, no test procedures for the various ICs. I've been using the schematics supplied by Michael Buchner to me that are far superior to the factory ones and this has been a major asset. I am NOT a professional electronics repair tech by any means, but I do have a basic understanding of what the various electronic components are supposed to do and have limited schematics reading ability. Fortunately my soldering skills are much better than my "diagnosing" skills. This is why I've been asking advice here to help point me in the right direction. It may seem to some that I'm just randomly replacing parts, but I am going on the theory that these components are nearly 30 years old and are near the end, if not already at, the end of their life and should be replaced anyway in order to make it function correctly again. I have been going in stages as suggested by others here, and as it is, I'm having progress. Limited as it may be, but it is still progress. I am closer to it being fixed more tonight, than any time in the past. Recapping it helped the sound AFTER I replaced the mux/demux 4051 ICs and IC61. The sound quality is even better after replacing the mux/demux tl084 ICs, and it has resolved a couple of the issues I was having, but not all.
>
> Again, thanks to those who have helped here by steering me in the right direction, especially Michael for the great schematics and advice.
>
>
> --- In Simmons_Drums@yahoogroups.com, "simmonssds7fan" <ptmetcalf@> wrote:
> >
> > Progress report: replaced IC61 and the six 4051 demux chips, no real change other than the sound generation is a bit stronger. The original random triggering issue is still there. The TL084 chips arrive tomorrow. I'll see what transpires after the replacement of those. Starting to lean towards IC58 being the problem, but I guess it won't hurt to replace those TL084s either.....
> >
> > --- In Simmons_Drums@yahoogroups.com, "simmonssds7fan" <ptmetcalf@> wrote:
> > >
> > > I should have the replacement 4051s here today, so this may be a nice starting point on this project for the weekend. I ordered some tl84s as a precaution (they were cheap) just in case the 4051s aren't the entire problem. I also ordered a replacement IC for IC61 and am planning on changing that one out as well as the six 4051s. I didn't think of changing IC58, but if replacing these seven IC's doesn't change much, I may get one of those and change that one out before changing all the tl84's. I'm jumping the gun a bit I suppose, but I need to have some kind of game-plan right?
> > >
> > > Thanks to everyone with helpful insight to the workings and faults to these SDS-9 units, it is much appreciated. I'll keep everyone up to speed with what happens after the 4051 replacement.
> > >
> > > --- In Simmons_Drums@yahoogroups.com, "Richard" <warlandr63@> wrote:
> > > >
> > > > I like Michael have repaired quite a few SDS9's in my time and fully agree with what he is saying. 95% of the random triggering issues I have dealt with were the result of a faulty 4051's the others were due to faulty address decoders (IC's 58 and 61) or dud bypass caps associated with the demux circuit (creating noise spikes)
> > > >
> > > > Here is my take... Replace (ic socket fitted at same time) IC19,IC64,65,66,67 and 68. Replace ALL 100nf decoupling caps for these IC's also (you have already done this I see) The parts are cheap and once this has been done you will know for certain that the demux section can be ruled out. We can then go from that point to narrow down the fault.
> > > >
> > > > As to recapping...well that is a subject that stirs up a hornets nest every time it is mentioned. To state that capacitors "wear out" is a bit of a false statement. They simply don't. BUT there are types that can and will deteriorate over time to a point that they no longer function as a capacitor (acting more like a resistor or going dead short) or there rated value at time of manufacture is way out.
> > > >
> > > > Ceramics, mylars and the like are generally quite robust and don't need replacing (unless they have been stressed beyond ratings due to PSU fault or similar)
> > > > Tantalum caps usually fail dramatically releasing magic smoke in the process. They are notorious for failing and in any "vintage" gear I replace them...THEY WILL FAIL< IT"S JUST A MATTER OF TIME.
> > > > Electrolytics also fail on a regular basis. The electrolyte dries out over time causing drift of value and voltage piercing through between the plates (dead short)
> > > >
> > > > I speak from experience, 35 yrs as an electronics engineer and technician working with gear from the simplest up to highly accurate and sensitive lab gear in universities. I can say without exception any equipment I have recapped has benefited greatly from the work carried out. Gear that once was way out of spec would become usable once again. Yes the process of electronic repair can insert new faults, but in due care is taken during the process this is minimized. It's not rocket science but a bit of knowledge and understanding certainly goes a long way.
> > > >
> > > > Richard
> > > >
> > > >
> > > > In Simmons_Drums@yahoogroups.com, "Michael Buchner" <buchnerelectronics@> wrote:
> > > > >
> > > > > Start with the 4051s. In most cases...
> > > > >
> > > > > Best
> > > > >
> > > > > Michael
> > > > >
> > > >
> > >
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> And Gordon, I do understand what you are saying about test first, then replace. However, I do NOT own an oscilloscope, and the factory service manual is only schematics, no test procedures for the various ICs. I've been using the schematics supplied by Michael Buchner to me that are far superior to the factory ones and this has been a major

Okay, you really do need to get an oscilloscope. They're not expensive. Pick up a dual-trace analogue 'scope from someone who will allow you to go along to pick it up in person, and get them to show you it working.

This will make everything easier. Working without the basic test equipment (even just a good meter and 'scope) is a bit like a heart surgeon saying "well I don't have a chest saw so I just chop my way in with a fire axe"...

Testing the chips is merely a matter of making an educated guess at how the output is going to look given the input. It's worth considering that the 4051s and accompanying TL084s are acting as a unit to form a multiplexer and sample-and-hold - so compare the input of the MUX with the output of the buffer, first.

> asset. I am NOT a professional electronics repair tech by any means, but I do have a basic understanding of what the various electronic components are supposed to do and have limited schematics reading ability. Fortunately my soldering skills are much better than my "diagnosing" skills. This is why I've been asking advice here to

help point me in the right direction. It may seem to some that I'm

I do tend to cast a suspicious eye over 405x MUXes and their buffer amps *but I test them first* ;-)

> just randomly replacing parts, but I am going on the theory that these components are nearly 30 years old and are near the end, if not already at, the end of their life and should be replaced anyway in order to make it function correctly again. I have been going in

They don't really wear out, although they do fail. Some synths seem to be worse than others in this regard, possibly due to design factors.

> stages as suggested by others here, and as it is, I'm having progress. Limited as it may be, but it is still progress. I am closer to it being fixed more tonight, than any time in the past. Recapping it helped the sound AFTER I replaced the mux/demux 4051 ICs and IC61. The sound quality is even better after replacing the mux/demux tl084 ICs, and it has resolved a couple of the issues I was having, but not all.

Again, you could save yourself a lot of time and money with the proper tools. Pick up a 'scope for £50 or so, and it will save you so much bother. Bear in mind you don't necessarily need it to be accurately calibrated - you're mostly looking for qualitative rather than quantitative measurement, ie. "Is this actually a square wave?" rather than "Is this exactly 4.75V peak-to-peak?". The former kind of question crops up in diagnostics all the time, the latter almost never...

> Again, thanks to those who have helped here by steering me in the right direction, especially Michael for the great schematics and advice.

It sounds like you're making good progress, but seriously - buy a 'scope. And once you've done that, you get to work out how to get at the bits of the board in the middle of a stack ;-)

--
Gordonjcp MM0YEQ