Dynaco-Doctor Forum

RE: PAS-3 right channel hum

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Okay, so it is not in the original, stock configuration, meaning, you have the cap board replacing the quad section capacitor and the filament supply. Perhaps there have been other changes, I don't know. Hum problems are notoriously difficult, and your PAS having undocumented changes could make a solution more elusive.

It could be helpful to know where the other ends of the wires at eyelets 1 and 8 go. However, if the goal here is to get the hum equal in both channels, here is something you can try. Any rework I describe here should be done with reversal in mind, in other words, don't do anything that cannot be put back the way it was.

You know your black wire that goes to eyelet 8 underneath the board? I can't quite tell from the image, but if the other end of this wire is soldered to the ground lug on the chassis, then I suggest removing this wire from the underside of eyelet 8. Insulate the bare end of the wire so it cannot short to anything.


On the top side of the PC board at eyelet 8, you have a black wire that goes to the cap board (the red, tubenirvana power supply board). I suggest moving this wire from the top side of eyelet 8 to the top side of eyelet 1. This might be tricky, because you already have several wires at eyelet 1. Be sure that none of the wires can short to the chassis or anywhere else other than where they are supposed to go.

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