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> Amp -> Bad Tube, No Sound
Frankster
post Sep 28 2012, 06:52 PM
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Hi!

I am playing an Egnater Rebel 30 Amp

At the last band rehearsal I thought that the tone of the amp gets a litte fuzzy and that the amp lost some power.

Today I played the amp again and it sounds ok and after 30 minutes it made a gentle "plop" noise and the sound was gone. I tried the EL84 position I tried the 6V6 position but no sound. And one of the 6V6 tubes doesnt glow.

So my question is.
The reason of no sound is a dead tube or another problem?

Many Thanks
Frankster
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jstcrsn
post Sep 28 2012, 11:05 PM
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QUOTE (Frankster @ Sep 28 2012, 06:52 PM) *
Hi!

I am playing an Egnater Rebel 30 Amp

At the last band rehearsal I thought that the tone of the amp gets a litte fuzzy and that the amp lost some power.

Today I played the amp again and it sounds ok and after 30 minutes it made a gentle "plop" noise and the sound was gone. I tried the EL84 position I tried the 6V6 position but no sound. And one of the 6V6 tubes doesnt glow.

So my question is.
The reason of no sound is a dead tube or another problem?

Many Thanks
Frankster

most likely its a tube , don't toggle the switch any more
don't change the tubes yourself as they hold a small amount of current ( could shock you )
I just let a pro change mine , that way it is done safe and I dont screw up my amp

This post has been edited by jstcrsn: Sep 28 2012, 11:06 PM
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Todd Simpson
post Sep 28 2012, 11:35 PM
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Take it to a pro ASAP like folks are saying. It's a nice amp so diagnosing it over the forum may not be your best best. Probably well worth getting it in to the hands of a pro.

Todd

QUOTE (Gregit @ Sep 28 2012, 05:32 PM) *
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GregH
post Sep 28 2012, 11:48 PM
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It could be the tube but it could be something else too.
The filament should glow visibly in any working glass envelope tube. However, it is relatively rare for a tube to lose its filament (and quit glowing). Sometimes a tube will have dirty contacts where it plugs in. Then wiggling it or unplugging it and plugging it back in will fix it.
Also, on the Rebel 30 you have two sets of output tubes, so loosing one tube shouldn't make both the 6V6 and the EL84 side quit completely.
So, my guess is that there is another issue.
I am assuming that by glowing you mean a dull red (or orange) in the center of the tube. If the whole inner structure of the tube is a somewhat bright red then the inside of the tube is trying to melt. That can also be caused by a bad tube but will mean that tubes and probably other parts will need to be changed.
As jstcrsn stated, you need to be somewhat cautious when working on tube amplifiers. The internal voltages on the output tubes in this amp are likely to be around 400 volts dc. The tubes themselves (in amplifiers we are likely to see) don't actually store voltages (the internal capacitance is too low) but the filter caps in the amplifier can keep an uncomfortably amount of voltage for a few hours (usually it will drop below the potentially fatal range in a half hour or so).
So, if you don't know the safety rules for working around high voltage, find someone who does to do the work.
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derper
post Sep 29 2012, 04:54 AM
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Great advice from all. Gotta love GMC! Keep it safe, and take it to an amp tech. biggrin.gif


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Check out my awesome Nintendo Cover-band, EMULATOR!!
http://www.reverbnation.com/emulator

Now.....go practice!!
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Dieterle
post Sep 29 2012, 08:46 AM
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Yes, i myself would do it to an Amp doctor too!
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