damage to bass amp head?

[Vitrolin]

to what is your audio probe connected?
do you have an 10:1 oscilloscope probe?
if yes, there is no need for a voltage devider, as it is allready in you probe.
if not what are you using?

[Dimitree]

to what is your audio probe connected?

to the input of another amplifier,
it sounds fine when I audio probe on R1, so I can't explain how it could be a preamp problem.. But if I disconnect the preamp, the buzz is gone

do you have an 10:1 oscilloscope probe?
if yes, there is no need for a voltage devider, as it is allready in you probe.
if not what are you using?

my cheap oscilloscope doesn't have that, so I need an external voltage divider, as I said I did that test and rails looks quite fine

[R.G.]

Sigh.

This isn't going anywhere.

[Dimitree]

Sorry, I didn't have my solder iron with me so I couldn't remove the output transistors, in the meanwhile I was trying to measure what I could