[sdiy] Verbos Buchla 258 VCO Debug Help

[Romeo Fahl]

I built a dual vco from this schematic:

http://www.simple-answer.com/258mod.jpg

Something's not quite right though.  Turning the frequency pot or 
inputting a control voltage results in almost no change in the 
oscillator's frequency.  I do have a waveform at the output and 
sweeping the waveshape pot does vary the waveform as expected.   
Inputting an lfo into the FM input results in the vco waveform starting 
and stopping as the lfo amplitude reaches maximum extremes.

I've gone through the circuit with a fine-toothed comb, several times, 
and can't figure out why it's not working.  Replaced the 3080 and 
3140... no change.  I used an MAT03 instead of the SSM2220.  They've 
always worked in vco expos before, so I don't see why that would be a 
problem.

Might be a matter of not seeing the forest for the trees, need to step 
away from it for a bit.  If anyone has any thoughts as to what might be 
wrong, please drop me a line.

Romeo