Question about Audio Players & Recorders

2 Answers

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.


Posted by eloo on

  • 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.



2 Answers


  • Level 1:

    An expert who has achieved level 1.

  • Contributor
  • 1 Answer


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


Scott Frye

  • Level 3:

    An expert who has achieved level 3 by getting 1000 points


    An expert that got 10 achievements.


    An expert that got 5 achievements.


    An expert who has answered 1,000 questions.

  • Master
  • 1,175 Answers

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


Add Your Answer

Uploading: 0%


Complete. Click "Add" to insert your video. Add



Related Questions:

1 Answer

I have a Peavey Bandit 50 watt guitar amplifier that has no output with the exception of what seems to be a 60 cycle hum.

The schematic I grabbed from shows several fuses in the power supplies. Did you check those, especially the one for the high voltage supply for the output tubes - fuse F1 on 'main board' ?

Feb 06, 2018 | Peavey Music

1 Answer

Brand new Peavey 6505. Worked fine first day but now just blows fuse and doesn't even turn on. Will be going back but has anyone got any ideas?

Something internally has shorted...not a good indicator of this models reliability. It may pay to research another replacement brand.

Dec 28, 2013 | Peavey 6505 120w All Tube Head Guitar...

1 Answer

My amp stopped working after 2 days from the day bought it. It stayed on standby for a while, about ten to fifteen minutes, but once I switched it on it started humming and making crack and pop noises.I...

Take it back for warranty replacement or repair since you only had it for 2 days. Since there is burnt smell this could be very serious problem. Probably a fuse blew due to any of several problems.

The pilot light runs off a rectified output of the power transformer but it is fused. There are three sopplies from the transformer and any of those could have a short and blow the main fuse or their individual fuses.

Take it in as I stated as this is NOT DIY repair. There are high voltages in this unit and if one is not adept at electronics you probably would not be able to repair it anyway.

Nov 29, 2010 | Peavey ValveKing VK112 50W Combo Amplifier

1 Answer

Howdy, I have the mains light on and the pre-amp valves light up but the power valves wont light up. I've replaced the 10amp ceramic fuse and can hear hum but still no light on the EL84's. The amp was...

Since the pilot light is on, the transformer is delivering the heater power.

An educated guess at the problem is a crack on the circuit board or bad solder joint. Since NONE of the EL84's are lit, there is likely a crack or soldering at a circuit board feed-thru.

Should be easy to trace. PLEASE be careful as there is around 400 volts in this amp !!!!!

Sep 29, 2010 | Peavey Classic 30112 Tweed

1 Answer

I have a peavey classic 20 guitar amp that works as normal when switching on but after a couple of minutes the power amp tubes (EL84's) just switch off. What could the problem be?

What do you mean they "switch off"??? If the heaters in all the tubes go out, check the fuse for the heaters, F2 and its fuse clips/holder.

There really is nothing in the circuit to make them "switch off"

If the heaters in the EL34's "switch off", the other tubes should go out as well.

Jan 25, 2010 | Peavey Music

1 Answer

Hi, My Peavey Classic 50/50 has power (leds are lit) but the tubes show no sign of life - no output at all and no active lit tubes with the power tubes or the input 12ax's - I have checked the fuses and...


I had checked the fuse for the heater circuit and found that while it was testing on a low ohm check meter - it was not sufficiently handling the
full demand of the circuit - I put a bypass on the fuse and found the problem. The fuse appears to have been previously replaced with
a type not original - the original was a ceramic case fuse 10A.

I appear to be operational


Dec 27, 2009 | Peavey Music

1 Answer

Hi, Peavey Classic Guitar amp , Has NO SOUND

Hi Mike,

If you switch on the amplifier, do you hear nothing at all?
Or do you hear low level noise or hum out of the speaker?
Don't know if you're technician.
If the tubes are glowing, you can measure the high voltage.
Check also fuse 3 and 4, thats the neg. voltage -27V and -14V.


Jul 06, 2009 | Peavey Audio Players & Recorders

2 Answers

1995 Jeep Wrangler 2.5 4cyl spits and sputters while driving

if you have an electric fuel pump that would explain the hum. unhook your incoming fuel line and blow the line clear, sounds like you've got some junk in your'll build up on the screen in the tank then fall off (at least partially) when your making turns or hitting bumps or holes. next time it's only got a gallon or so of fuel i'd drop the tank and check the pickup tube inside. sux but that's the only way to get to it. while you've got the tank off and out from under the jeep, might as well clean it out real good and replace anything inside (usually the screen) that doesn't look right, dirty etc. wouldn't hurt to run a bottle of fuel system cleaner in the next full tank of fuel either. preferably as soon as you put your tank back. good luck

Mar 25, 2009 | 1995 Jeep Wrangler

2 Answers

A HUMMING Peavey Classic 30

I repaired a classic 50 recently and the problem was a bad solder connection on the main input jack. You may also want to have the tubes tested.

If the unit is over 20+ years have it recapped.

I do this stuff but Vermont might be to far.


Mar 17, 2008 | Audio Players & Recorders

Not finding what you are looking for?
Audio Players & Recorders Logo

Related Topics:

1,752 people viewed this question

Ask a Question

Usually answered in minutes!

Top Audio Players & Recorders Experts


Level 3 Expert

13434 Answers


Level 3 Expert

5700 Answers

The Knight
The Knight

Level 3 Expert

76287 Answers

Are you an Audio Player and Recorder Expert? Answer questions, earn points and help others

Answer questions

Manuals & User Guides