saint gillis
Well-known member
I had to fix of of these, the right side power amp was showing heavy distortion awful sound. I first re-soldered the suspicious points and the amplifier came back to life again.
After 3 or 4 times using it during few hours each times, the problem came back again.
There is a negative feedback from the output to a differential pair at the input, I tried to ground or to remove the feedback on the functional left amplifier, but the circuit seems not to work this way (negative -60V rail at the output of the amp). So I measured and compared voltages on the left and right amps (the functional one and the distorted one), they were all the same. Then I put the oscilloscope and realised the distorted amp was working correctly again...
Is this a bad transistor somewhere?
After 3 or 4 times using it during few hours each times, the problem came back again.
There is a negative feedback from the output to a differential pair at the input, I tried to ground or to remove the feedback on the functional left amplifier, but the circuit seems not to work this way (negative -60V rail at the output of the amp). So I measured and compared voltages on the left and right amps (the functional one and the distorted one), they were all the same. Then I put the oscilloscope and realised the distorted amp was working correctly again...
Is this a bad transistor somewhere?
