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
>