> Dieter,
>
> I have set up the first Quantizer without difficulty, but working on
> the second has shown that the output voltage is unstable (it warbles
> almost as mouch as one semi-tone. I've switched out the TL062CN and
> the main processor chip (PIC16F73). I don't have the other two chips
> handy to try changing. Is this a return to Doepfer case, or is there
> something else I can try The problem manifests on quantizers 1 and 2
> (on the same module).
>
> Yours Aye
>
> Stuadh

Please measure the voltages directly at the ouputs of the DAC. These are the
pins 11 and 12 of the TLC5620. If these are stable it seems like a problem
with the TLC274. The TLC274 is used only for buffering and amplifying the
DAC outputs. If you have no TLC274 available you may use also a TL064 or
TL084 or LM324. If this does not help add a small ceramic capacitor (~
100pF) to the feedback of each output OpAmp. These are the pins 1/2 (or
across R16) and 7/6 (across R19) of the TLC274.

Best wishes
Dieter Doepfer