check the capacitor before the waveshaper chip... between the osc and waveshaper.... sorry I cant remember the wavshp pin outs, but I had exactly what you are describing by simply replacing the cap at signal in...
-----Original Message-----
From: effegee <floobygoop@...>
To: yamahacs80@yahoogroups.com
Date: 04/10/2011 01:12
Subject: [yamahacs80] Help needed with bad waveshaper IG00158
On my CS-80, I have one bad voice and have checked the VCO chip (IG00153) output from pin 7 with an oscilloscope and it looks fine. However, on the IG00158 waveshaper I don't get output from pin 2 or 5 and an extremely low amplitude wave from pin 7. With this particular voice, there is a tuned, very low level, high band frequency sound (a buzzing) that responds to velocity, the suboscillator, aftertouch, VCF, VCA, etc., so I think the circuit is good after the waveshaper. I've ordered a new IG00158 chip, hoping that replacing it will fix the problem. Is there anything else I should check? I'm planning on soldering in a socket to push the chip into. Any recommendations? Can I just pick up a 16-pin socket from Radio Shack?
[Non-text portions of this message have been removed]
-----Original Message-----
From: effegee <floobygoop@...>
To: yamahacs80@yahoogroups.com
Date: 04/10/2011 01:12
Subject: [yamahacs80] Help needed with bad waveshaper IG00158
On my CS-80, I have one bad voice and have checked the VCO chip (IG00153) output from pin 7 with an oscilloscope and it looks fine. However, on the IG00158 waveshaper I don't get output from pin 2 or 5 and an extremely low amplitude wave from pin 7. With this particular voice, there is a tuned, very low level, high band frequency sound (a buzzing) that responds to velocity, the suboscillator, aftertouch, VCF, VCA, etc., so I think the circuit is good after the waveshaper. I've ordered a new IG00158 chip, hoping that replacing it will fix the problem. Is there anything else I should check? I'm planning on soldering in a socket to push the chip into. Any recommendations? Can I just pick up a 16-pin socket from Radio Shack?
[Non-text portions of this message have been removed]