Yamaha CS80

Merry Xmas guys,

Here's what I decided to do during my Xmas holidays....

I decided to service and perform some of the mods to one of my CS80's
- namely to replace all Power Supply filter caps, then set the
voltages. Next I wanted to do the decoupling mods to the TKC board as
outlined on Scott's site. Then I wanted to tune her up using a dual
beam scope as has been mentioned here before now.

OK, I did the PSU caps and the voltages set up fine. Next I soldered
very carefully all those .1 caps across all 28 IC's on the TKC board.
I even added the electrolytics (the correct way round on the +8.5 and
-6.5 volt feeds) and I was wrist-strap-earthed throughout. When I
fired her up it all worked fine and I set about tuning her up.

So far so good. The tuning went well and I was really happy with what
I had done - I left this machine on for quite some time and played her
almost all day a couple of days ago. Remember, this was a 100% working
synth before I opened her up...!!!

Today however I turn her on - and I notice that a voice is out on
Channel 1. Hmmm... I check the card and there's no waveforn on the O/P
of the Osc chip. So that's a chip gone down. Next I notice I have no
aftertouch... Hang on, it seems intermittent here and there. It has a
weird pattern .... some notes intermittent, others just don't respond
to after touch and then the lowest octave seems to have a mixture of
notes with NO aftertouch and others with constant MAX aftertouch.

I reckon I've disturbed something somewhere and maybe I shouldn't have
attempted this servicing after all...?


I am concerned as I wanted to perform these exact procedures on my
other 100% working CS80. But I fear I won't have a working one between
them if I do..!


Could any techs here maybe point me in the direction of how to
determine which 40XX IC on the TKC board services which note's
aftertouch on the keyboard? The manual doesn't make that clear at all
(to me anyway)

Cheers for now guys, hope you all have a better one that I'm having.
I think a drink is in order now....;^(

TOM

wow, that sucks Tom

I changed the supply filter caps in my CS80.. however in my experience
its best to leave things alone unless they are having issues.. the ol'
if it ain't broke don't break it school of thought.

I've had some serious discussions with some of the most qualified
synth techs in the world regarding CS80 and other synth "reliablity
mods" most seem to agree, they will do them so they can make a living
but they are generally not needed unless the synth is acting up.

I wish you luck getting that back 100%.. having a working unit for
comparison will be helpful if you have a scope and meter... too bad
the boards are hardwired or you could just swap cards until you found
the faulty boards.

-r

--- In yamahacs80@yahoogroups.com, "Quazimodo" <noddyspuncture@...> wrote:
>
> Merry Xmas guys,
>
> Here's what I decided to do during my Xmas holidays....
>
> I decided to service and perform some of the mods to one of my CS80's
> - namely to replace all Power Supply filter caps, then set the
> voltages. Next I wanted to do the decoupling mods to the TKC board as
> outlined on Scott's site. Then I wanted to tune her up using a dual
> beam scope as has been mentioned here before now.
>
> OK, I did the PSU caps and the voltages set up fine. Next I soldered
> very carefully all those .1 caps across all 28 IC's on the TKC board.
> I even added the electrolytics (the correct way round on the +8.5 and
> -6.5 volt feeds) and I was wrist-strap-earthed throughout. When I
> fired her up it all worked fine and I set about tuning her up.
>
> So far so good. The tuning went well and I was really happy with what
> I had done - I left this machine on for quite some time and played her
> almost all day a couple of days ago. Remember, this was a 100% working
> synth before I opened her up...!!!
>
> Today however I turn her on - and I notice that a voice is out on
> Channel 1. Hmmm... I check the card and there's no waveforn on the O/P
> of the Osc chip. So that's a chip gone down. Next I notice I have no
> aftertouch... Hang on, it seems intermittent here and there. It has a
> weird pattern .... some notes intermittent, others just don't respond
> to after touch and then the lowest octave seems to have a mixture of
> notes with NO aftertouch and others with constant MAX aftertouch.
>
> I reckon I've disturbed something somewhere and maybe I shouldn't have
> attempted this servicing after all...?
>
>
> I am concerned as I wanted to perform these exact procedures on my
> other 100% working CS80. But I fear I won't have a working one between
> them if I do..!
>
>
> Could any techs here maybe point me in the direction of how to
> determine which 40XX IC on the TKC board services which note's
> aftertouch on the keyboard? The manual doesn't make that clear at all
> (to me anyway)
>
> Cheers for now guys, hope you all have a better one that I'm having.
> I think a drink is in order now....;^(
>
> TOM
>

happy holidays tom! so sorry to hear about your situation here, that sucks! ive been there(there being the place you are when replacing parts surfaces a NEW problem), very frustrating, you earned that drink sir.

while i cant help you with your particular issue regarding CMOS id-ing, i did want to weigh in on your other cs-80, and doing this job on it.

i have learned a ton of things off of scotts old crow site, and the pictures alone are worth their weight in gold. it is an amazing resource. im merely weighing in to pass along another side of the coin. when i got my cs-80 this year, i planned on a full restoration. i did the PSU, and calibrated voltages, then tuned. i was planning on doing all the CMOS chips per scotts site, but just to double check, i weighed in at Dave Hecht's tech forum(mostly pro audio, good number of experienced techs in there) on how best to replace all the CMOS chips on all 4 of the boards underneath the manual.

the majority of the responses there urged me to reconsider "shotgunning" parts, and specifically called into question the practice of replacing CMOS chips as preventative maintenance. most tech people there said that it is a bad idea. i had already started the job(was using sockets), but stopped where i was per their suggestions. i have all the chips/sockets to finish the job, but decided to wait until i see a problem to tackle those boards. i did not perform the decoupling caps on the TKS board yet. i am not in any way calling into question the validity of either side of this, as i am ultimately not an experienced enough tech to have fallen on one side or the other yet to know how I feel personally! im merely saying that the jury may not be completely unanimous on the idea of replacing CMOS chips as preventatively sound. however, i doubt that many folks are more experienced than scott and kent on these matters, so i would personally put more stock in their opinions than
most!

merry christmas, and be thankful for your working cs-80!


Quazimodo <noddyspuncture@...> wrote: Merry Xmas guys,

Here's what I decided to do during my Xmas holidays....

I decided to service and perform some of the mods to one of my CS80's
- namely to replace all Power Supply filter caps, then set the
voltages. Next I wanted to do the decoupling mods to the TKC board as
outlined on Scott's site. Then I wanted to tune her up using a dual
beam scope as has been mentioned here before now.

OK, I did the PSU caps and the voltages set up fine. Next I soldered
very carefully all those .1 caps across all 28 IC's on the TKC board.
I even added the electrolytics (the correct way round on the +8.5 and
-6.5 volt feeds) and I was wrist-strap-earthed throughout. When I
fired her up it all worked fine and I set about tuning her up.

So far so good. The tuning went well and I was really happy with what
I had done - I left this machine on for quite some time and played her
almost all day a couple of days ago. Remember, this was a 100% working
synth before I opened her up...!!!

Today however I turn her on - and I notice that a voice is out on
Channel 1. Hmmm... I check the card and there's no waveforn on the O/P
of the Osc chip. So that's a chip gone down. Next I notice I have no
aftertouch... Hang on, it seems intermittent here and there. It has a
weird pattern .... some notes intermittent, others just don't respond
to after touch and then the lowest octave seems to have a mixture of
notes with NO aftertouch and others with constant MAX aftertouch.

I reckon I've disturbed something somewhere and maybe I shouldn't have
attempted this servicing after all...?

I am concerned as I wanted to perform these exact procedures on my
other 100% working CS80. But I fear I won't have a working one between
them if I do..!

Could any techs here maybe point me in the direction of how to
determine which 40XX IC on the TKC board services which note's
aftertouch on the keyboard? The manual doesn't make that clear at all
(to me anyway)

Cheers for now guys, hope you all have a better one that I'm having.
I think a drink is in order now....;^(

TOM






---------------------------------
Never miss a thing. Make Yahoo your homepage.

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

Ah welcome to my world!

I got some idea what you might have done here. Tell me what keys
have no AF and what one's do. I can then tell you what ic's have
gone if any.

Did you hit the AF connecter board on the top of the psu?

If your geting some notes with full AF you may have joined some legs
together when putting the 0.1 caps on.

Let us know all the faults and I will help you out as I am working
right though the Christmas holiday anyway. ( on 80's as always )

KSR


--- In yamahacs80@yahoogroups.com, "Quazimodo" <noddyspuncture@...>
wrote:

>
> Merry Xmas guys,
>
> Here's what I decided to do during my Xmas holidays....
>
> I decided to service and perform some of the mods to one of my

CS80's

> - namely to replace all Power Supply filter caps, then set the
> voltages. Next I wanted to do the decoupling mods to the TKC board

as

> outlined on Scott's site. Then I wanted to tune her up using a dual
> beam scope as has been mentioned here before now.
>
> OK, I did the PSU caps and the voltages set up fine. Next I

soldered

> very carefully all those .1 caps across all 28 IC's on the TKC

board.

> I even added the electrolytics (the correct way round on the +8.5

and

> -6.5 volt feeds) and I was wrist-strap-earthed throughout. When I
> fired her up it all worked fine and I set about tuning her up.
>
> So far so good. The tuning went well and I was really happy with

what

> I had done - I left this machine on for quite some time and played

her

> almost all day a couple of days ago. Remember, this was a 100%

working

> synth before I opened her up...!!!
>
> Today however I turn her on - and I notice that a voice is out on
> Channel 1. Hmmm... I check the card and there's no waveforn on the

O/P

> of the Osc chip. So that's a chip gone down. Next I notice I have

no

> aftertouch... Hang on, it seems intermittent here and there. It

has a

> weird pattern .... some notes intermittent, others just don't

respond

> to after touch and then the lowest octave seems to have a mixture

of

> notes with NO aftertouch and others with constant MAX aftertouch.
>
> I reckon I've disturbed something somewhere and maybe I shouldn't

have

> attempted this servicing after all...?
>
>
> I am concerned as I wanted to perform these exact procedures on my
> other 100% working CS80. But I fear I won't have a working one

between

> them if I do..!
>
>
> Could any techs here maybe point me in the direction of how to
> determine which 40XX IC on the TKC board services which note's
> aftertouch on the keyboard? The manual doesn't make that clear at

all

> (to me anyway)
>
> Cheers for now guys, hope you all have a better one that I'm

having.

> I think a drink is in order now....;^(
>
> TOM
>

Thanks Kent, I really appreciate your offer of help sir!

OK this is gonna be kind of difficult to explain...

I'll call the lowest C- C1 and the highest C- C6.

Here goes...

C1, Eb1, F#1, A1, C2 ... all at full AT.
The notes in between these have no AT.

C#2 > F#2 .. all OK

G2 > C4 are behaving now an then "intermittently".

C#4 > F#4 .. all OK

G4 > C6 .. all have no AT

There is a weird anomally though....

When I press any of the intermittent keys when they are working, and
then I press one of the full AT keys at the same time it makes the
ones that are working (the intermittent one), STOP working.

And the other way, if I hold down a full AT key and press one of the
intermittent ones at the same time, the full AT disappears, cuts off
to nothing. This must be a clue...?

I checked all my soldering - was the first thing I looked at with a
magnifying glass and there are no visible joins. My soldering is quite
good as I went to college years ago and passed some electronics courses.

BTW Kent, when you mentioned the AF board you mean the small one to
the left of the keyboard assembly I asume? I think I avoided it (I'll
double check) - but anyway this problem seems strange in that
everything was working just fine for a day or two after I did all the
work. This all happened this morning.

Thanks again Kent,
And thanks to all of you who replied as well.

Tom

--- In yamahacs80@yahoogroups.com, "kent_spong" <kent_spong@...> wrote:
>
> Ah welcome to my world!
>
> I got some idea what you might have done here. Tell me what keys
> have no AF and what one's do. I can then tell you what ic's have
> gone if any.
>
> Did you hit the AF connecter board on the top of the psu?
>
> If your geting some notes with full AF you may have joined some legs
> together when putting the 0.1 caps on.
>
> Let us know all the faults and I will help you out as I am working
> right though the Christmas holiday anyway. ( on 80's as always )
>
> KSR
>

I had another look Kent,

The small aftertouch circuit board is fine - no damage.

I now notice that hitting ANY key while a full AT key is playing cuts
off the full AT..!

Cheers,
Tom

--- In yamahacs80@yahoogroups.com, "kent_spong" <kent_spong@...> wrote:
>
> Ah welcome to my world!
>
> I got some idea what you might have done here. Tell me what keys
> have no AF and what one's do. I can then tell you what ic's have
> gone if any.