Ampeg BA115HP Output and crackling/static

[g1]

You should always look first to the big electronics suppliers for parts so you won't get counterfeits from China. J112's are around 50 cents each at mouser or digikey.

[ca7922303]

So finally got around to installing Q6/Q9 and now have no output headphone or speaker. Connections to all six(6) pins are good.

[g1]

In post #163 did you have headphone output?
Nothing you have done since then could affect the headphone out. Maybe something in your test setup is not right.

[ca7922303]

Installed new Q6/Q9 and all other parts that were removed have been reinstalled.

[x-pro]

The headphone output and speaker output here are from different points.
The headphone amplifier is the output of the preamplifier. It is also the XLR output. If the headphone output is there and the output amplifier is good, then the speaker output should be there too.
The output of the power amplifier is connected to the speaker.
There is no headphone output here as is customary- via resistors connected to the speaker.
Check the position of the MUTE switch.

[ca7922303]

The headphone output and speaker output here are from different points.
The headphone amplifier is the output of the preamplifier. It is also the XLR output. If the headphone output is there and the output amplifier is good, then the speaker output should be there too.
The output of the power amplifier is connected to the speaker.
There is no headphone output here as is customary- via resistors connected to the speaker.
Check the position of the MUTE switch.

Mute switch is off.

[ca7922303]

Reflowed Q4 collector:
Q4-B (+3vdc)C(+50vdc)E(+2.4vdc)@(107vac Variac)
Q1-B (-3vdc)C(-50vdc)E(-2.6vdc)
TP10(-70mvdc)
TP12(0.4mvdc)
Q1-B-E(-0.5vdc)
Q4-B-E(-0.5vdc)
U5-Pin 5(-0.7mvdc)
Have normal headphone output, but no speaker output.

Checking back over some of the previous measurements, Q1 is the same,
Q4(+5vdc)B, C, E Q1/Q4 B-E is the same
U5-Pin 5(16vdc)

[ca7922303]

What is DC volts at each end of R34?

R34(-0.00mvdc)

[ca7922303]

R50(+17/-5.8vdc)

R50(+17/+6vdc)

[ca7922303]

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

R44(+2/+6vdc)
AP1(+1/+1/+1)

[ca7922303]

Check resistance of R22 and R26. Check that resistance from U5 pin1 to pin5 is 1K.
Check that DC volts at U5 pins 4 and 8 are -15V and +15V.

If all that checks out, replace U5.

R22(1k ohms)
R26(46.4 ohms)
U5 pin 4(-6mvdc)
U5 pin 8(+16.7vdc)

[ca7922303]

Q9 gate to ground w/o headphones(0.8 ohms)
Q9 gate to ground with headphones(23ohms)

Q9 gate to ground(270k ohms)

[x-pro]

U5 pin 4(-6mvdc)

I've never seen such contradictory electrical voltages before.
It's nonsense.
Why is there almost zero on pin 4 of U5?

[x-pro]

Q4(+5vdc)B, C, E Q1/Q4 B-E is the same

How's that? If on Q1 b(-3V), why is AP1 1V on all pins.

[x-pro]

R34(-0.00mvdc)

I don't know here either.
If it is 0, then there is no +50V voltage.