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Peavey classic 50/50 keeps blowing fuses.

I put new gt el84 power tubes in my peavey classic 50/50. It ran fine for a couple days and then started blowing fuses. Now when I turn it on it hums very loud for a second or 2 then pops the fuse. Did I Blow the power OT by not rebiasing the amp. Any Info would be nice.


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  • dannod57 May 11, 2010

    I've got a Classic 50-410. The Classic is a fixed bias amp and cannot be adjusted (unless you modify the rig). You may have a bad tube or a bad cap or diode in the power supply. I run the JJ EL84 (6BQ5). If I were you, start swapping out the EL84s 1 at a time (like Thumbsmagee said) with your old ones (if you still got them) to see if you can pin down which tube maybe bad. There also may be a bad 12AX7 in the Preamp section (uses 3ea) as well, so don't rule that out. I doubt you have any O.T. damage.



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I have a classic 50/50 as well and re-tubed it with JJ el84s, vintage teslas and mullard 12at7s. As long as you replaced it with EL84s, I can't imagine that the output would be increased enough to damage the OT. When I got my 6505 Combo, one of the 6L6s was bad, and it kept blowing fuses and howling like a banshee. I would think that an OT problem would result in a significant loss of output...or none at all. I've gotten DOA tubes from a few places. I would suggest swapping each tube out 1 by 1, until you find it...if that is indeed the problem...before you pay the cash to have it worked on.

Posted on Oct 29, 2007

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The BIAS circuit may have failed and is allowing the power tubes to max out over their spec?

Or you have a tube with an internal short that's killing the high voltage every time you power up.

I have yet to see an output transformer fail out of over 100 amps I've done

Posted on Dec 16, 2014


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