Ampeg BA115HP Output and crackling/static

[ca7922303]

Yes, Q6/Q9 removed.

[g1]

So now there isn't even a difference between TP12 and TP10 with signal applied? What signal level are you getting at TP6 and 7 ?

[ca7922303]

So now there isn't even a difference between TP12 and TP10 with signal applied? What signal level are you getting at TP6 and 7 ?

JW6(0.25vac)
JW7(0.25vac)
TP10(0.22vac)
TP12(0.28vac)
Didn't have gain and master@10 on previous post.

[ca7922303]

J112 ok to to replace J111 with?(Q6/9).J111s take a bit longer to get than J112s.

[x-pro]

Undesirable. They have different control voltages Ugs. This may be important for Q6.
Next repair option. We will look for a fault in the power amplifier.
Q6 is not soldered. Q9 is not soldered, but there is a jumper between its D-S.
Unsolder C11, and then solder only its negative lead to R25. Connect +C11 to GND. You can solder any other (1µf-47µf/35-100V) in place of C11 (10µf).
Check all supply voltages directly at the output transistor pins. Carefully. (+50В,-50В,+16В,-16В)
Again measure the DC voltage at TP11 when there is no signal at the input. Also measure the DC voltage at TP12. Note all the DC voltages taking into account the polarity.
Now disconnect +C11 from GND and apply a sinusoidal signal from a 1 kHz 250 mV RMS oscillator to +C11.
Measure the AC current in TP12, TP10, TP11. Do not connect a load to the output!

[ca7922303]

Undesirable. They have different control voltages Ugs. This may be important for Q6.
Next repair option. We will look for a fault in the power amplifier.
Q6 is not soldered. Q9 is not soldered, but there is a jumper between its D-S.
Unsolder C11, and then solder only its negative lead to R25. Connect +C11 to GND. You can solder any other (1µf-47µf/35-100V) in place of C11 (10µf).
Check all supply voltages directly at the output transistor pins. Carefully. (+50В,-50В,+16В,-16В)
Again measure the DC voltage at TP11 when there is no signal at the input. Also measure the DC voltage at TP12. Note all the DC voltages taking into account the polarity.
Now disconnect +C11 from GND and apply a sinusoidal signal from a 1 kHz 250 mV RMS oscillator to +C11.
Measure the AC current in TP12, TP10, TP11. Do not connect a load to the output!

Please give me the number from the schematic of which supply voltages at the output transistor pins you want checked.

[ca7922303]

Undesirable. They have different control voltages Ugs. This may be important for Q6.
Next repair option. We will look for a fault in the power amplifier.
Q6 is not soldered. Q9 is not soldered, but there is a jumper between its D-S.
Unsolder C11, and then solder only its negative lead to R25. Connect +C11 to GND. You can solder any other (1µf-47µf/35-100V) in place of C11 (10µf).
Check all supply voltages directly at the output transistor pins. Carefully. (+50В,-50В,+16В,-16В)
Again measure the DC voltage at TP11 when there is no signal at the input. Also measure the DC voltage at TP12. Note all the DC voltages taking into account the polarity.
Now disconnect +C11 from GND and apply a sinusoidal signal from a 1 kHz 250 mV RMS oscillator to +C11.
Measure the AC current in TP12, TP10, TP11. Do not connect a load to the output!

TP10(-6.6vdc)(0.2vac)
TP11(-43mvdc)(11vac)
TP12(+0.0mvdc)(0.3vac)

[x-pro]

TP10(-6.6vdc)(+0.2vac)
TP11(-43mvdc)(+11vac)
TP12(+0.0mvdc)(+0.3vac)

Under what conditions were these measurements made?
What is what? How can VAC have polarity?

[x-pro]

Please give me the number from the schematic of which supply voltages at the output transistor pins you want checked.

For example Q2, Q5.
Also, what is the DC voltage across b-e Q4 and Q1? There is no signal at the input.

[ca7922303]

Under what conditions were these measurements made?
What is what? How can VAC have polarity?

Per your post#65. I followed your instructions to the letter and gave the voltages that you asked for on TP10/11/12.

[x-pro]

what is the DC voltage across b-e Q4 and b-e Q1? There is no signal at the input

[g1]

Under what conditions were these measurements made?
What is what? How can VAC have polarity?

In post #65 you asked for 2 sets of measurements, first DC (no signal), the AC (signal applied). I think the post #68 are the 2 sets of results, though I am not 100% sure.
In post #47, he gave Q1 and Q4 DC voltages that did not agree with DC from post #68 (6VDC at TP10), although in post #47 the load may have been connected.

[x-pro]

A person can make a mistake, measure incorrectly. So I asked again to specify the voltages between the base and emitter of these Q4 Q1, especially there are non-compliances.

[x-pro]

is that what you have now?

[ca7922303]

is that what you have now?

Ill have to get back on it this evening after work. Thanks.