Archive of the former Yahoo!Groups mailing list: Yamaha CS80

So, I just finished replacing almost all of the 4000 series logic IC's in my Yamaha CS-80. I
totally screwed it up. I've got sustaining voices, unusual behavior and a couple of voices
that only track the keyboard if you play a few notes at the same time.

In retrospect, replacing most of the IC's might have been a bad idea. One theory that I
have is that the 4006 registry shifters that I couldn't replace are having problems keeping
up with the propagation delay of the new IC's? Furthermore, soldering a cap across the
rails on the TKC board might have been a bad idea too. Electrically, it doesn't make any
sense to couple two rails together but a respectable website suggested it and other people
said that it didn't cause any adverse affects?

Is there any systematic proceedure for restoring these things? Initially, I was hesitant to
turn any of the potentionometers - I figured that the thing would probably get back into
calibration once I replaced the faulty IC's. I was scared of stressing the potentionometers
too. Maybe I should have calibrated it after I recaped and before I installed all of the new
IC's. Some of the calibration proceedures were off by significant values - another reason I
figured that my problem was rooted within the IC's.

Here's a brief synopsis of the problems I'm facing:

1.) Before I replaced the IC's square wave output was distorted if more than one voice was
sounding. This was basically the main reason I replaced most of the IC's. I still have this
problem.

2.) One voice, the last voice played, sustains indefinately in sustain I and II.

3.) Aftertouch doesn't work on the voice that is sustaining.

This thing is really sick and hard to isolate problems. I don't have it in front of me either
so it's harder to blog about it.

Does anybody have any suggestions or referrals?

-Mike
312-363-7286