I'm having a slight but annoying problem with my silver face '84 (possibly) Twin Reverb.
When I switch it on an tubes are warming up (with both switches, power and standby thrown into the up position), I'm hearing a hum that start a bit louder and then fades to become fainter, but it does not totally disappear.
Only when I then use the zero out hum trim pot on the rear and turn t with a screw driver such that the hum totally disappears - and when I say "totally", I mean totally. I can zero out the hum so that the amp sounds like not being switched on at all.
So far so good.
But next time I switch on the amp the hum is there again and I have to find another point with the trim pot to zero out the hum.
In the old forum when I posted the problem (under user ChristophK, which can be back 7 or 10 years ago), someone said, I should do a modification to the wiring of the pilot lamp (add some resistor(s) or so).
Any clues?
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Christoph