Ampeg BA115HP Output and crackling/static

[x-pro]

Q4-B(- 5.9vdc

so there's a reverse voltage on C31?

[ca7922303]

Measurement points.

Q3 doesn't even need to be unsoldered to measure its b-e

R44(-7/-11vdc)
AP1(-12/-12vdc)
Don't see a C41 on either the schematic or the pcb.

[g1]

He said C31, not 41 (at Q4 base). And he asked for B to E voltage for Q3, so one probe at each. (black to Q1 base, red to R43/44 junction).

[ca7922303]

He said C31, not 41 (at Q4 base). And he asked for B to E voltage for Q3, so one probe at each. (black to Q1 base, red to R43/44 junction).

C31(Don't know the answer)
b-e voltage for Q3(0.65vdc)

[x-pro]

What chip is now in place of U5 ?
Does the R50 rating correspond to 1k?
Is there +50V on R34 ?

[x-pro]

TP10(0.09vac)
Q1-E(-2.6vdc)C(-57vdc)B(-3.1vdc)
Q4-E(+2.4vdc)C(+57vdc)B(+2.9vdc)

where did those values go?

[ca7922303]

What chip is now in place of U5 ?
Does the R50 rating correspond to 1k?
Is there +50V on R34 ?

U5 has a new NE5532P chip(bought from Amazon) R50 slowly climbed to (0.9k ohms)
R34(+61vdc)

[ca7922303]

where did those values go?

Currently:
Q1-E(-11.7vdc)C(-60.7vdc)B(-12.2vdc)
Q4-E(- 7.3vdc)C(-7.3vdc)B(-6.6vdc)

[x-pro]

What is the voltage on the bottom pin of R31?
I ask because for IRFP140 and IRFP9140 the D-S voltage is 100V.
If the lower supply is also more than 50V, it is very bad for these transistors. The voltage is too high.

[x-pro]

Q4-E(- 7.3vdc)C(-7.3vdc)B(-6.6vdc)

?
Do the collector and emitter have the same values? Are you sure?
Unsolder Q4 and check it!

[x-pro]

Is U5 well soldered in?

[ca7922303]

?
Do the collector and emitter have the same values? Are you sure?
Unsolder Q4 and check it!

Yes, collector and emitter have the same voltage

[ca7922303]

Is U5 well soldered in?

Checked all pins of U5 to each pins nearest component and they were all connected.

[ca7922303]

?
Do the collector and emitter have the same values? Are you sure?
Unsolder Q4 and check it!

Unsolder Q4 and describe how to check?

[x-pro]

Multimeter in diode mode. Red probe on B, black probe on C, then on E. The values should be similar, in the range of 560-700mV. B-E should be higher.
There should be no short between E-C.