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Thanks in advance for any advice.
The amps hums loudly, and the amplitude of the hum increases as I turn up the master volume. If I engage the lead channel by pulling out the volume knob, the gets a little quieter. Also, as I turn up the volume (gain) in the 3-7 range a buzz appears that disappears once the gain goes over 7.
Here is what I have done so far. I changed the tubes; no change in hum. I changed the filter caps (the amp probably needed then changed since it is over 20 years old); no change in hum. I cleaned the gain and master pots; no change in hum. I checked the continuity of the ground from the plug to the chassis, and it is OK.
Can anyone suggest the next steps I can take? Could it be a bad pot? Any help would be greatly appreciated.
All the best,
The amps hums loudly, and the amplitude of the hum increases as I turn up the master volume. If I engage the lead channel by pulling out the volume knob, the gets a little quieter. Also, as I turn up the volume (gain) in the 3-7 range a buzz appears that disappears once the gain goes over 7.
Here is what I have done so far. I changed the tubes; no change in hum. I changed the filter caps (the amp probably needed then changed since it is over 20 years old); no change in hum. I cleaned the gain and master pots; no change in hum. I checked the continuity of the ground from the plug to the chassis, and it is OK.
Can anyone suggest the next steps I can take? Could it be a bad pot? Any help would be greatly appreciated.
All the best,