It appears that the rail supply is working normally. I'm not sure that the 2.94 is right but the circuit is producing rail voltage and regulating it.
What's the DCV on the PS terminals of the various op-amps on the preamp board?
What's the DCV on the output of the 5v regulator?
What's the DCV on the PS terminals of the various op-amps on the preamp board?
What's the DCV on the output of the 5v regulator?
Still no audio?
Have you operated all pots and switches in all possible combinations while driving audio into the amp to see if you get any sound through the output?
Are all channels silent?
DCV on the 3rd leg of the J111 FETs behind the audio driver boards?
Side note... For the preamp board, I'd run a strand of wire through all of the vias that were not absolutely perfect, soldering to the top and bottom pads/traces.
Have you operated all pots and switches in all possible combinations while driving audio into the amp to see if you get any sound through the output?
Are all channels silent?
DCV on the 3rd leg of the J111 FETs behind the audio driver boards?
Side note... For the preamp board, I'd run a strand of wire through all of the vias that were not absolutely perfect, soldering to the top and bottom pads/traces.
I think I missed your posting of the 234 voltages. are you sure that pin 7 was 0.0v?
Are the voltages the same (± 2 or 3%) of the voltages you posted?
Are the voltages the same (± 2 or 3%) of the voltages you posted?
If the amp starts to produce audio again, recheck the voltages on pins 5, 6 and 7 of the LM324.
DCV on each terminal of R611 near the 10-pin connector?
Is the LM324 running hot?
DCV on each terminal of R611 near the 10-pin connector?
Is the LM324 running hot?
correct, it produces audio again
Pin 5: 6.7
Pin 6: 4.0
Pin 7: 7.7
R611: 6.77 and 6.0
They don't heat up too much
Pin 5: 6.7
Pin 6: 4.0
Pin 7: 7.7
R611: 6.77 and 6.0
They don't heat up too much
It's going to have to quit again to troubleshoot further. When it quits, check the same points as above to see how they have changed.
Can you heat/cool/flex anything in the amp to make it quit?
Can you heat/cool/flex anything in the amp to make it quit?
Ok, I've turned it off and on again. I see that the values of pins 5,6 and 7 have changed. More than anything, pin 7 doesn't maintain the 12.18v as you show in the tutorial. Where do those 12.18v come from?
This is a standard op-amp. The IC could be intermittent. When pin 5 is higher than pin 6, pin 7 should go high unless it's shorted to ground. When pin 7 goes to 0v, measure the resistance from pin 11 to pin 7. Red on pin 7. Do the same on diode-check. Does it ever read 0 ohms 0r 0v (diode-check)?