I dont have audio output in all 4 channels .
And Yes , all one terminal connected to ground
There were revisions on many of the amps that told tech to remove various resistors on the input. They were typically from the shield and from the center-conductor of the input RCAs to ground. If those are what's missing, the problem is likely elsewhere. Have you operated all pots and switches through their entire range while listening for audio on the dead channels?
I find audio signal on a terminal of the driver card ab output board. And I detect that it responds to the gain and crossover switch settings and frequencies in all ranges. both in high and low frequencies.
I changed R202 22 ohms in two cards corresponding to the front channels
I add the comment: When moving the bias potentiometers of the 4 channels there is no response
Someone previously moved them
Attachments
Do all driver boards have the same DCV measured directly across the resistors R208, R210 and R212?
On the resistors of all the driver boards
R210: -13.5v at both ends of each resistence
R208: 000v at both ends of each resistence
R212: 000v at both ends of each resistence
I corrected the measurement method. I did it directly across each resistor
In all measurements
R210: .000v
R208: .003v
R212: .001
From the audio I have it through C200 on each driver board
In all measurements
R210: .000v
R208: .003v
R212: .001
From the audio I have it through C200 on each driver board
U100
Pin 1: .023
Pin 2: 12.07
Pin 3: 13.26
Pin 4: 4.97
Pin 5: 7.26
Pin 6: 4.97
Pin 7: 8.40
Pin 8: 1.363
Pin 9: 4.32
Pin 10: 3.85
Pin 11: 4.97
Pin 12: .022
Pin 13: 12.07
Pin 14: 10.64
U102
Pin 1: 10.40
Pin 2: 4.75
Pin 3: 13.27
Pin 4: 1.371
Pin 5: 3.80
Pin 6: .040
Pin 7: 8.60
Pin 8: .021
Pin 9: .020
Pin 10: .040
Pin 11: 8.69
Pin 12: .022
Pin 13: 10.39
Pin 14: .021
Pin 1: .023
Pin 2: 12.07
Pin 3: 13.26
Pin 4: 4.97
Pin 5: 7.26
Pin 6: 4.97
Pin 7: 8.40
Pin 8: 1.363
Pin 9: 4.32
Pin 10: 3.85
Pin 11: 4.97
Pin 12: .022
Pin 13: 12.07
Pin 14: 10.64
U102
Pin 1: 10.40
Pin 2: 4.75
Pin 3: 13.27
Pin 4: 1.371
Pin 5: 3.80
Pin 6: .040
Pin 7: 8.60
Pin 8: .021
Pin 9: .020
Pin 10: .040
Pin 11: 8.69
Pin 12: .022
Pin 13: 10.39
Pin 14: .021
Something is preventing C107 from charging.
C107 could be shorted/leaky.
R105 could be out of tolerance
Pin 7 of U100 could be shorted to ground (unlikely).
Resistance across terminals of C107?
C107 could be shorted/leaky.
R105 could be out of tolerance
Pin 7 of U100 could be shorted to ground (unlikely).
Resistance across terminals of C107?
U100 is defective . Pin 1 to shorted to ground .
Perry Babin .Thanks for your time and help
Solved
Perry Babin .Thanks for your time and help
Solved