Shorted tube, should I look the amp over?

sbelyo · 595

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Offline sbelyo

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on: June 01, 2021, 04:09:22 PM
I had the right channel tube short tonight.  The tube had 1000 hrs or less on it.  Should I check the amp over?  It's been running fine for like 7 years so not sure where to look.



Offline Paul Birkeland

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Reply #1 on: June 01, 2021, 04:24:52 PM
Is the tube showing shorts in a tester, or something else?  You can check the resistances in the amp, but provided the fuse is still OK, I would put a fresh tube in and keep rolling.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline sbelyo

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Reply #2 on: June 01, 2021, 04:31:06 PM
I turned the amp on and waited a few minutes then plugged in the headphones.  I heard a hiss then a few pops so I took the headphones out and shut the amp off.  I tested the tube and it showed a short in the tester.  I put a new tube in and the amp was fine.  I just didn't want to ruin another pair of tubes because I didn't check something.



Offline Paul Birkeland

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Reply #3 on: June 01, 2021, 04:46:05 PM
You can certainly check the voltages with the new tube.  What I would look closely at would be the condition of the 1000uF capacitor in that channel to see if its body is bulging, especially at the top.  With all the voltage bled off, you could check the DC resistance of each plate choke to be sure they are still about the same.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man