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

I'm working on a CS80 that does not have any VCF sub-oscillator modulation with after-touch on voice 2. (Voice 1 and 3-8 are normal) I have traced this to an IG00151 on the TRG3 board (IC10) that has zero output. Input voltages all look normal (comparable to the other 7 channels), but the output always is 0V.

I tested the possibility of a short in the circuits being driven from the TRG3 board, so I removed the F2 output signal. The resistance of the F2 wire to ground is normal (about 14K), and the output of IC10 (pin 8) is still 0V when voice 2 is pressed (aftertouch) and the VCF after touch response control is set to maximum (VCF signal (66) input to TRG3 is 10V). This makes me think IC10 is defective.

Can anyone think of anything else that could cause this sympton (other than a defective IC10)?

If IC10 has indeed failed, can anyone recommend a source for replacement? Is anyone selling any TRG boards from a CS80 or CS50?

Thanks!