No leftchannel audio - LED off - voltages incl. [resolved]

EDick · 1251

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Offline EDick

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on: October 07, 2020, 02:54:43 PM
Hey there folks,

Having audio issues with my standard crack, figured I would post my voltages. No audio unless I pull the jack out somewhat, which I know just results in improper mono audio.

1 - 87.5
2 - 165.6
3 - 0
4 - 165.7
5 - 150
6 - 0
7 - 106.7
8 - 0
9 - 150
10 - 0

Thanks in advance! Hope everyone is doing well.
« Last Edit: November 01, 2020, 04:26:29 AM by Paul Birkeland »


Offline Paul Birkeland

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Reply #1 on: October 07, 2020, 03:31:12 PM
Are both halves of the 12AU7 glowing?  What's your DC voltage at A3 (only applicable if both halves of the 12AU7 are glowing)?

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline EDick

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Reply #2 on: October 07, 2020, 05:33:02 PM
Sorry, forgot to mention, only one half of the tube is lit. One LED is out in the socket below, I can double check which if necessary.

Thanks!


Offline Paul Birkeland

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Reply #3 on: October 07, 2020, 06:56:17 PM
The connection at A4/A5 is not solid.

-PB

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline EDick

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Reply #4 on: October 08, 2020, 07:33:13 AM
Thanks a lot PB!

I'll check it out later today and get back if I need anything else. Y'all are amazing, love this amp.


Offline EDick

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Reply #5 on: October 08, 2020, 01:12:47 PM
Alright, I resoldered the A4/A5 connection, but half of the tube is still unlit. Any other ideas? Thanks.


Offline Paul Birkeland

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Reply #6 on: October 08, 2020, 02:05:29 PM
Either tube is bad or your solder joint is bad.  It's incredibly rare to have half a 12AU7 stop glowing.  I have tested literally thousands of 12AU7s, and I've seen it maybe 3 times.  Most Cracks that I have repaired have flaky solder joints ;)

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline EDick

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Reply #7 on: October 31, 2020, 07:24:57 PM
Just replying for those that might find this post in the future...

Believe it or not, it was actually the tube that was bad. I was fairly surprised, but I'm glad it was just as simple as that.
Threw in a Tungsol 12AU7 and it's working like a charm!

Thanks for all the help PB. Can't wait for my next inevitable purchase.


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