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I know the answer. Money. We'll start at the end.
So I finally finished quite a painful surgery on my Jet City JCA50H that was only partially successful. I initially planned to cut the traces to the preamp heaters to raise them above the board and away from any components causing hum. I did the raising part, but I didn't do the elimination of hum part. I thought I had ruined something, but it turned out I must have damaged the V1 tube while I was in there, since I had initially attached the wires backwards. I don't understand why it would matter since the heaters are AC, but I finally got the point of eliminating bad tubes as a source of failure, and that ended up being the problem.
That was all the failure. The depth pot and the sweep pot are both wins. The depth pot makes the overdrive channel much more useable by allowing me to dial out some of the excess bass. And the sweep pot lets me dial out some of the extra brightness that made the crunch channel harsh at times and that the presence control couldn't fix. I only have about ten minutes worth of play time in since the changes, but it's amazing what a little extra time and about $5 in parts can buy you.
In case anyone is interested in the necessary steps, I'd be glad to provide detailed explanations via PM.
So I finally finished quite a painful surgery on my Jet City JCA50H that was only partially successful. I initially planned to cut the traces to the preamp heaters to raise them above the board and away from any components causing hum. I did the raising part, but I didn't do the elimination of hum part. I thought I had ruined something, but it turned out I must have damaged the V1 tube while I was in there, since I had initially attached the wires backwards. I don't understand why it would matter since the heaters are AC, but I finally got the point of eliminating bad tubes as a source of failure, and that ended up being the problem.
That was all the failure. The depth pot and the sweep pot are both wins. The depth pot makes the overdrive channel much more useable by allowing me to dial out some of the excess bass. And the sweep pot lets me dial out some of the extra brightness that made the crunch channel harsh at times and that the presence control couldn't fix. I only have about ten minutes worth of play time in since the changes, but it's amazing what a little extra time and about $5 in parts can buy you.
In case anyone is interested in the necessary steps, I'd be glad to provide detailed explanations via PM.