02-21-2018, 09:03 AM
Is the plate voltage the same on all the power tubes?
I originally thought HF oscillation. But then I saw that it was only on one side. And you've basically replaced everything. Except the output transformer.
Given that pointing a finger at the OT is not making me feel super helpful, the other possibility is one or more of the sockets on that side. Clean/re-tension? Maybe re-flow the solder connections on the socket? Remember that the problem might not be on the side that is red-plating. Those tubes could be biased too hot because the other side is running cold for some reason.
I originally thought HF oscillation. But then I saw that it was only on one side. And you've basically replaced everything. Except the output transformer.
Given that pointing a finger at the OT is not making me feel super helpful, the other possibility is one or more of the sockets on that side. Clean/re-tension? Maybe re-flow the solder connections on the socket? Remember that the problem might not be on the side that is red-plating. Those tubes could be biased too hot because the other side is running cold for some reason.