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