Yamaha CS80

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
>