The signal on the rectifiers shouldn't show up on the drains. The amplitude will be similar but it's an entirely different signal.
What signal do you have on pins 3, 4 and 11 of the LM361?
Set the scope's vertical amp to 5v/div. Set the timebase to whatever produces ~3-5 cycles on the display (~5uS).
Here is the rundown of what voltages/waveforms are on what pins of the LM361N with the probe grounds referenced to negative speaker input. I changed the scale on some to better view the waveform.
Pin 1: +12VDC
Pin 3: One picture AC coupled, one DC
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Pin 4: One picture AC coupled, one DC
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Pin 6: -12VDC
Pin 8: +3.1VDC
Pin 9: +1.98VDC
Pin 10: -1.98VDC (Should the GND pin be at a different voltage than the negative speaker terminal?)
Pin 11: -1.82VDC
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
This is approximately the same style of waveform that shows up on the output transistors
Pin 13: +3.1VDC
Pin 14: +3.1VDC
After looking through the datasheet for the LM361N, it looks like everything is correct as far as inputs go... two triangle waves at the input (except maybe the DC offset on pin 3?) and both strobe inputs are held high. The output is obviously low. Is it a fair assumption the LM361N is bad or are there some other components I should look at?