I'm attempting to repair an integrated tube amplifier for a friend. I believe it's a Vincent TAC with EL34 tubes. The fault is a dead channel which might have been caused by a bad tube. I've replaced a couple of burnt out resistors, and the dead channel is now alive but badly distorted. I compared resistances in the output transformers and one of them is unfortunately damaged.
My question is: Is it advisable to replace both output transformers even though only one is damaged? I imagine it might be difficult to find a new transfomer with exactly the same specs as the old ones.
My question is: Is it advisable to replace both output transformers even though only one is damaged? I imagine it might be difficult to find a new transfomer with exactly the same specs as the old ones.
I think the only good option is to replace both. But assuming the amp uses global feedback, the circuit will have to be retuned to avoid instability. I would not drop in new transformers and assume the amp will be stable. Do you have a schematic? And, more importantly, an oscilloscope?
I've tried to find schematics, but no luck so far. Which is strange considering the model isn't uncommon. I do have an oscilloscope.
Okay, well, you'll be able to test it. You could measure the primary impedance of the good transformer and look for a new pair with the same basic specifications.