Archive of the former Yahoo!Groups mailing list: 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