1966 Traynor YBA-1 Repair:
A customer brought me this YBA-1 for repair. It was a basket case. As with many vintage tube amps, this one had seen many "repairs" and "modifications" over the years, until finally it no longer worked, and was pretty far from the original circuit design.
The output transformer was bad. Unfortunately, it was intermittently bad, which made it hard to troubleshoot. The defining clue was the black hole (see right) in the windings, which told of a dead short in the transformer primary winding.
Traynor used very big (and expensive) transformers. But exact replacements are still made. I replaced the transformer after aging the new one and using the bell ends from the original. You can't tell it has been replaced.
There were numerous amateur modifications to the amp; someone had tried to modify it to copy the Marshall Plexi circuit, which is a common mod for this amp, but they had failed miserably. I put the amp back to the 1966 YBA-1 circuit.
This YBA-1 is a loud amp - I can't believe it is rated 40 Watts; It is louder than a Twin! It is a great, great little amp, and is still available at reasonable prices. I see them sold for less than $300 occasionally - but people are catching on to the value of this amplifier, and I have seen some sell for over $800. (sigh).