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March 28, 2024, 01:47:28 PM

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Tube Amp Trouble

Started by saturated, March 18, 2024, 06:20:21 PM

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saturated

Newly acquired Savage Rohr 15

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When I got it it seemed to work ok both channels four inputs...

I thought it didn't seem to have much gain but figured it was what it was.

I guess it had/has a problem because later it seemed to get quieter and quieter and finally one channel appearing inop and the other both volume knobs can be max and strumming a guitar 🎸 can be heard at low volume.

I worked up enough courage to take a look and perhaps see something.

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I looked at the chassis but did not touch or 🥢 chopstick anything.

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Also I reconnected the speaker before powering on.

Btw here is the tubes

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When I powered it on I noticed one 12ax7 was not glowing as well as the uncovered tube on the end which I presume to be a 12at7 (?)

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I guess I made a big mistake by not swapping a preamp tube to see if it was the tube or the chassis.

I carefully put everything back together and not too eager to further investigate until I can watch hours of reruns on YouTube about at least some basics of working on and around these units.

I also have read a bunch of the threads in this section so I'm expecting to be told check voltage ⚡ on pins xx on vx.

 :P

But alas I think this is gonna be on the back burner for a while.  I just don't yet have the stomach for poking around this amp.

Thanks

 :-X

I ask stupid questions
and make stupid mistakes

criticism, critique, derision, flaming, verbal abuse welcome

saturated

Maybe that tube being not lit up doesn't mean anything idk

But forgot to add I did have the reverb out of it idk if that matters

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 :P
I ask stupid questions
and make stupid mistakes

criticism, critique, derision, flaming, verbal abuse welcome

g1

Sometimes certain ones don't light up as much as others.  But that one picture in the dark, it doesn't look like they are lit at all.  You could feel them to confirm. (just the preamp tubes, power tubes or rectifier tube will burn you)

The red and purple wires at the sockets are the heater wires.  Looks like they are all connected.  You can swap some preamp tubes around to find out if maybe the tubes themselves are bad.  Make note of where the 12AT7 belongs, but it can be swapped around for test purposes.

Once you have read up on safety for working in tube amps, you can measure those heater voltages at the tube sockets.  Should be about 6VAC with one probe to red and other probe to purple.

Tassieviking

If you are very very lucky it might be so simple its just a bad connection in the tube socket.
Pull the tubes out and reinstall them a few times just to make sure, if you have some Deoxit give the sockets a spray.

Just remember that there is high voltages in tube amps and the capacitors can stay charged for a long long time, be very careful so you don't damage the amp when you get knocked across the room from a charged capacitor. ;)
There are no stupid questions.
There are only stupid mistakes.

saturated

Thanks guys you ROCK  8)



I was gonna name this thread something like the trials and tribulations of tubes
:P
Then it got me thinking about a particular TV show episode.

Then I was gonna post a picture joking that it showed a rare sighting of some of our top ssguitar techs

I can only speculate who is who.  :)

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 :P
I ask stupid questions
and make stupid mistakes

criticism, critique, derision, flaming, verbal abuse welcome