This isn’t a vcc issue, all the chips have good power. Something is nudging the comparator out of balance, apparently it wasn’t U517 though. Same result after I replaced it.
I don't have notes on it but 1,7v on the triangle waveform seems low. The 555 is powered from the 5v. Why is the triangle at only 1.7v?
I assumed by “input to the 319” you meant the audio input, so that’s the pin I gave. The triangle is fine, perfectly linear as viewed on the scope and matches another board I have here in amplitude.
Both boards I have here measure at 2.198vdc for the triangle pin, it’s pin 4 of U511 that’s the problem.
When I asked "What's the DCV on the input to the NJM319?" and you said 1.7v. I assumed you meant both inputs since you gave only one voltage.
With a second working amp there, you should have no problem finding the problem.
With a second working amp there, you should have no problem finding the problem.