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Hoffman Amps Forum image Author Topic: AC30 clone outer tubes in quad redplating?  (Read 2157 times)

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Offline fdesalvo

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AC30 clone outer tubes in quad redplating?
« on: December 07, 2022, 03:01:46 pm »
Hello, all. Have any of you seen this before? Newish hayseed 30 build no leaky caps resistors test good. Very haphazardly assembled! Known good tubes redplate there as well.

Tia!
« Last Edit: December 07, 2022, 05:26:54 pm by fdesalvo »
~F
"Ruining good moments since 1975."

Offline sluckey

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Re: AC30 clone outer tubes in quad redplating?
« Reply #1 on: December 07, 2022, 05:41:00 pm »
Sounds like a perfect breeding ground for gremlins.   :icon_biggrin:
A schematic, layout, and hi-rez pics are very useful for troubleshooting your amp. Don't wait to be asked. JUST DO IT!

Offline JPK

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Re: AC30 clone outer tubes in quad redplating?
« Reply #2 on: December 08, 2022, 11:56:34 am »
Please see Slucky's signature.
I love tubes

Offline fdesalvo

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Re: AC30 clone outer tubes in quad redplating?
« Reply #3 on: December 08, 2022, 12:43:28 pm »
I sorted it out gentleman. Dying battery in my meter was masking the nearly 400v on the plates lol.  I swapped in an old 5R4 rectifier tube and she’s down to 306 V. No issues. Thank you.
~F
"Ruining good moments since 1975."

Offline tubeswell

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Re: AC30 clone outer tubes in quad redplating?
« Reply #4 on: December 08, 2022, 05:06:22 pm »
If you have only replaced 2 tubes in an output tube quad, you can get problems with one of the pairs under heavy signal conditions in some amps (when the 'hotter' pair ends up drawing more current- particularly in amps like 1959 Super Lead 100 Marshalls with EL34 quads where the B+ is 500). Which is why you need to be careful with quads.
A bus stops at a bus station. A train stops at a train station. On my desk, I have a work station.

Offline fdesalvo

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Re: AC30 clone outer tubes in quad redplating?
« Reply #5 on: December 08, 2022, 05:07:44 pm »
If you have only replaced 2 tubes in an output tube quad, you can get problems with one of the pairs under heavy signal conditions in some amps (when the 'hotter' pair ends up drawing more current- particularly in amps like 1959 Super Lead 100 Marshalls with EL34 quads where the B+ is 500). Which is why you need to be careful with quads.


Truth. I tested four new ones.
~F
"Ruining good moments since 1975."

 


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