Princeton 65 SS Intermittent Buzz

[DrGonz78]

We need dc volt measurements on U6 pins also. Note that JazzBass asked if the guitar’s volume control silenced the noise. The way I read it I could not tell if you were only referring to the amps volume control.

[Perkinsman]

Oooohhhhh, I missed that nuance in the jazzbass question, I wondered why people kept asking me the same question! The answer is my guitar volume doesn’t affect the volume of the buzz. The amp only controls the buzz volume. Here’s the U6 vdc:
pin 1=15.97
pin 2= 15.70
pin 3= .359
pin 4=-16.59
pins 5-8= 0

[Perkinsman]

I’m not sure what the correct ac or dc voltages are supposed to be on U6 as I don’t see them on the schematic.

Also, I could use assistance on signal trace setup with scope & signal generator. I also need help determining where the signal path is scope to trace. I’m not very astute reading a schematic.

[DrGonz78]

You should see -/+16 on pins 4 & 8. I would not expect to see those voltages on pins 1 & 2. I am working right now so can’t advise how to scope the signal. Someone else may help before I am back again.

[Perkinsman]

Do you suspect the IC itself? Your assist so far has been appreciated,

[DrGonz78]

You are missing the -16vdc on pin 8. Maybe a broken connection to that pin or bad solder joint. Get in there and trace continuity to pin 8.

Might as well check pin 4 & 8 on other Opamps to see what you get.