1987 50 watt Lead Series

[Trelwheen]

I took the back cover off and waited until it started humming again. Then I just tapped on the tubes. I didn’t know they got so hot? I could hear them when I was tapping them but the humming was still there. Are they supposed to get that hot?

Power tubes will get hot enough to ruin your afternoon if you grab one.

Did any of the tubes ring when you tapped them??

 

[79 2203]

I took the back cover off and waited until it started humming again. Then I just tapped on the tubes. I didn’t know they got so hot? I could hear them when I was tapping them but the humming was still there. Are they supposed to get that hot?

Yes, they’re supposed to get hot, but it’s all relative because some amps run hotter than others. I wouldn’t touch the tubes in my stock 71 1987 after it’s been running for a while, but compared to my stock 70 Superbass the 1987 runs much cooler. Mind you, both amps are pushed hard(1987 on 7, Superbass on 8)
Speaking of my 1987, just about every time I turn it on there is a loud hum. I asked on this forum about it and most replied that it was probably filter caps, or tubes. But one member commented that it could be a grounding issue on the pots and that often all it takes is to touch the vol or tone controls to fix it. Lo and behold it worked. The culprit seems to be mainly the unused Normal Vol knob and if I simply press on it, every time the hum stops and doesn’t come back(till the next time I turn it on)
Give it a try.

 

[Tatzmann]

Please stop the 30minute nonsense. You waste energy (your money) and its not beneficial for anything. If your Amp is on "Stby" the high tension is usually cut off, so your amp isn't even energized. Only the valve HEATERS (heaters=hot) are working, without a good reason for 30 minutes. The valves cathodes are at operating temperature after about 30 seconds of heating. As soon as your amp amplifies, operating temperature in the valves is reached.