Replaced one channel of the AB outputs and got all 4 AB output boards running.
Amp remains in mute. There is no gate voltage to any of the 4 Jfet muting transistors - not sure yet where the muting is for the Class D sub channel.
If I remove jfet channel operates normally.
All voltages are correct on all 5 channels.
Trying to trace out where muting originates. Maybe on the preamp board close to the remote power on section?
Anyone have any knowledge of what/where the muting circuits are?
Amp remains in mute. There is no gate voltage to any of the 4 Jfet muting transistors - not sure yet where the muting is for the Class D sub channel.
If I remove jfet channel operates normally.
All voltages are correct on all 5 channels.
Trying to trace out where muting originates. Maybe on the preamp board close to the remote power on section?
Anyone have any knowledge of what/where the muting circuits are?
I'm not sure on the 5ch but on the 500/1, the muting originates at the LM324 on on the preamp board near the power/ground terminals.
What's the DC voltage on the pins of that IC. Copy and paste the following list and fill in the blanks.
Pin 1:
Pin 2:
Pin 3:
Pin 4:
Pin 5:
Pin 6:
Pin 7:
Pin 8:
Pin 9:
Pin 10:
Pin 11:
Pin 12:
Pin 13:
Pin 14:
What's the DC voltage on the pins of that IC. Copy and paste the following list and fill in the blanks.
Pin 1:
Pin 2:
Pin 3:
Pin 4:
Pin 5:
Pin 6:
Pin 7:
Pin 8:
Pin 9:
Pin 10:
Pin 11:
Pin 12:
Pin 13:
Pin 14:
Pin 1: 1 v
Pin 2: 7.1 v
Pin 3: 4.4 v
Pin 4: 0v
Pin 5: 7.2 v
Pin 6: 6.4v
Pin 7: 10.9v
Pin 8: 11v
Pin 9: 7.1v
Pin 10: 9.6v
Pin 11: .2v
Pin 12: 4.6v
Pin 13: 6.7v
Pin 14: 1v
Pin 2: 7.1 v
Pin 3: 4.4 v
Pin 4: 0v
Pin 5: 7.2 v
Pin 6: 6.4v
Pin 7: 10.9v
Pin 8: 11v
Pin 9: 7.1v
Pin 10: 9.6v
Pin 11: .2v
Pin 12: 4.6v
Pin 13: 6.7v
Pin 14: 1v
Do you have negative 15v on any of the 10-pin connector terminals?
Do you see -15 on any of the small transistors in the 324 area of the preamp board?
If the preamp board has never been removed, try lifting it and then reseating it to see if that changes anything.
Do you see -15 on any of the small transistors in the 324 area of the preamp board?
If the preamp board has never been removed, try lifting it and then reseating it to see if that changes anything.
Follow the collector of that transistor through a resistor to the base of another transistor. That transistor should have -15 on its emitter.
I do see where the collector of the trans with the grounded base is also connected directly to the base of the resistor below it.
