[sdiy] Paia 9720 VCO Modulator?

[Diane&John Rose]

I am in the process of building a PAiA 9700 modular synth which is a great
synth but I am hung up in one spot and no matter what I have tried, I can't
get past it. I have even consulted numerous times with Paia tech support and
still cannot solve this mystery. The problem relates to the modulator
portion of the circuit, specifically the cycle mode. It is supposed to self
trigger and cycle by itself in this mode. Mine occasionally will cycle once
when the switch is in this mode and sometimes not. Sometimes it will cycle
once when switched to AR mode. Sometimes the LED will light briefly when I
turn the unit off. I have been over the circuit at least a dozen times
looking for problems. I have even changed out the LM324 opamp , related
transistors and capacitors all to no avail. I even get good readings on my
meter with voltages being as they should. Any insight as to what could be
going on would be most appreciated. This one has me stumped. Everything else
works great on this synth and the modulator triggers fine when triggered
from another source except that the attack and release seem to be reversed
even though the LED shows them to be normal. This is all very strange.
Thanks,

John
Music is at the heart of Creation.