Hi!
I’ve bought a Moog Source and my Emphasis doesn’t auto-oscillate at 99… I’ve tried to trim the Emphasis but it doesn’t work… Any ideas ???
Please help
Too many potential causes. Bad S&H, bad OTA, bad power supply, many others. Not easy to diagnose over the net.
U38 (3080 trans-conductance amplifier) functions as the feedback control that governs the resonance (emphasis). Is it working? Does the emphasis increase, just not to the point of self oscillation? If so, does the trim pot R164 have any affect? What does the signal on pin 1 of U13 (control signal S/H output to EMPH line controlling U38 pin 5 through R170) do when the emphasis parameter is changed from 0 to 99? Those are the first questions I would be answering if I was looking at this unit on the bench.
does the trim pot R164 have any affect?
Yes, I’ve trimmed R164 all way up and the Emphasis raise but not enough… I will check the U38. How can I adjust it anyway?