I am trying to restore an old diy amp which uses an Acrosound TO-300 transformer.
When I check the bias of the two EL-34 tubes, one reads 34v, while the one is 10v. In fact, the tube with the higher bias gets much warmer then the other.
All this while I have the amp on variac at around 80vac. There is a bias potentiometer between the tubes, but twisting it doesn't seem to change much anyway.
The amp was supposedly repaired professionally before I acquired it and some caps have been replaced, while others have been kept.
What should I start investigate first?
Thanks!
When I check the bias of the two EL-34 tubes, one reads 34v, while the one is 10v. In fact, the tube with the higher bias gets much warmer then the other.
All this while I have the amp on variac at around 80vac. There is a bias potentiometer between the tubes, but twisting it doesn't seem to change much anyway.
The amp was supposedly repaired professionally before I acquired it and some caps have been replaced, while others have been kept.
What should I start investigate first?
Thanks!
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