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Discussion Starter · #1 · (Edited)
Any insight appreciated please.

The amp was functioning flawlessly until the other night.

Brought it to a jam, upon which it made very little sound for about a minute, and then no guitar or speaker sound whatsoever. Before I pull it apart completely, is this typical, and if so, what are the likely causes?

What I've tested so far:

- speaker is good

- power indicator light goes on, amp hums quietly when powered up

- swapped tubes with known good ones - no change

- rectifier tube and power tubes both light up (warming circuit?)

- preamp tubes remain cold as ice with any combination of power/volume/input.

As these amps are apparently known for transformer issues, could this mean that the output transformer is done?

Thanks in advance
 

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when ever I lose sound on an amp, I've learned to check/clean the input jack first before I starting ripping and tearing things apart. The voltage is very low at that point and it doesn't take much to disrupt the flow. Spray some contact cleaner on your plug and jab it in and out for a bit.

Do the power tubes seem to be heating ok?
 

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Discussion Starter · #5 ·
Thanks. There are 4 input jacks (2 for each stage) and it's the same result with all, even after cleaning.

The power tubes and rectifier tube do seem to be heating OK. They're all visibly glowing and get quite hot.

I'm hoping that it's something simple like the heater wire coming off the preamp tube circuit, but can't get into the guts until later today.
 

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If there is not a fuse as i only see a mains fuse on most of the schematics & not exactly sure what amp you have ( if it's a hand wired clone or not ) if you are comfortable & have experience working on a tube amp I suggest removing the chassis & check the voltage on the heater wires , you said the preamp section is not lighting could be a cold solder joint on the heater wiring .
 
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