Losing left channel/high voltages post-Speedball install [Resolved]

aravenel · 1264

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Offline Paul Birkeland

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Reply #15 on: August 08, 2022, 10:30:13 AM
Sure, you could give that a try.  It may also be that the pins are a bit oxidized.  Just pressing them into a scotch-brite pad will often renew the pins a bit.

Paul "PB" Birkeland

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Offline aravenel

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Reply #16 on: August 08, 2022, 10:37:04 AM
Ah, good tip, that let me get a steady reading at least. Still open circuit b/t 5 and 9, reading 5.7 ohm b/t 4 and 9. Sound like a bad tube?



Offline Paul Birkeland

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Reply #17 on: August 08, 2022, 10:41:32 AM
On a very, very rare occasion the connections to the pins can break off inside the tube.  I think I've seen this maybe twice in twenty years, so it's not impossible, but still extremely likely.  Don't ask me how much time I spent trying to clean those pins before looking closely inside the glass and seeing the break!

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline aravenel

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Reply #18 on: August 08, 2022, 10:58:01 AM
Pulled out a magnifying glass and dont see any obvious breakages in there, but all the same... It seems like the obvious things have failed, so might as well try swapping the tube, at least rule that out.



Offline aravenel

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Reply #19 on: August 18, 2022, 05:34:09 AM
Update: New 12AU7 tube came in yesterday. Voltages are now in line, and a listening test has the left channel back to where it should be. I much appreciate all the help--super excited to have my amp back up and running!