Synth-DIY Yahoo! Groups Archives

Help needed with bad waveshaper IG00158

2011-04-10 by effegee

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?

Re: [yamahacs80] Help needed with bad waveshaper IG00158

2011-04-10 by Laurie Curry

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...

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-----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? 

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