Help!! Peavey 6505+ 112 combo cuts off

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Nrk
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Help!! Peavey 6505+ 112 combo cuts off

Post by Nrk » Fri Jul 07, 2017 10:24 pm

Everything will be working just fine and all of a sudden there's a loud hum which gets louder and the amp shuts off blowing a fuse!!! Please help!! :o

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Enzo
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Re: Help!! Peavey 6505+ 112 combo cuts off

Post by Enzo » Sat Jul 08, 2017 1:25 am

First two suspects are failed output tubes.

Nrk
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Re: Help!! Peavey 6505+ 112 combo cuts off

Post by Nrk » Sat Jul 08, 2017 10:54 pm

But then would they still play normally? It plays pretty well at starts and then all that happens

ScottMarlowe
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Re: Help!! Peavey 6505+ 112 combo cuts off

Post by ScottMarlowe » Sun Jul 09, 2017 3:43 pm

Yes. Tubes can fail in all kinds of fun and interesting ways. Being a mechanical device they often have issues from heat that don't show up right away.

Nrk
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Re: Help!! Peavey 6505+ 112 combo cuts off

Post by Nrk » Sun Jul 09, 2017 8:49 pm

Jeez Thanx!!! I had a doubt on d filter caps though... I'll check the tubes!!

Frankentar
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Re: Help!! Peavey 6505+ 112 combo cuts off

Post by Frankentar » Mon Jun 14, 2021 5:03 pm

I'm also having this problem.

The first time, having no idea what was going on, I replaced the little barrel fuse that screws into the back of the amp. Fixed the problem Worked fine for another couple months, then out of the blue, one day the volume dropped and was replaced by a hum -- started low then grew louder and louder until I shut it off.

Bought more fuses and replaced it again. Worked OK for a few weeks, the started the hum again.

Replaced yet again, and this time I only got a few minutes of playing time before the hum death cycle kicked in.

Any thoughts, anybody, on any fixes that I, who am not well-versed in electronics, might be able to do?

Many thanks!

Eric
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Princeton Reverb, Peavey VK 112, Roland Blues Cube Hot

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Enzo
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Re: Help!! Peavey 6505+ 112 combo cuts off

Post by Enzo » Tue Jun 15, 2021 12:46 am

Of course could be many things, but way most likely is a failing power tube. Whenever it has an internal fit, it blows your fuse. You replace the fuse, but the intermittent tube remains.

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JamesPaul
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Re: Help!! Peavey 6505+ 112 combo cuts off

Post by JamesPaul » Tue Jun 15, 2021 1:07 am

You won't be out anything by trying this as sooner or later you'll need new power tubes anyway. Personally, I also replace the phase inverter tube when I replace power tubes.
Enzo wrote:I find if the amp is working, that is a good point to stop fixing it.
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Decade, Classics, Ecoustic, Windsors, VYPYR, Triple XXX, XXL, VKs, Bandit, JSXs, VIP, Piranha and a Penta.

Frankentar
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Re: Help!! Peavey 6505+ 112 combo cuts off

Post by Frankentar » Tue Jun 15, 2021 11:05 am

Thank you!
What are the names/numbers of those power tubes and phase inverter tube? I’ll order them and give ‘em a run.
Really appreciate the help.
Eric
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Part-time builder of Fender-type guitars for personal consumption




Princeton Reverb, Peavey VK 112, Roland Blues Cube Hot

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JamesPaul
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Re: Help!! Peavey 6505+ 112 combo cuts off

Post by JamesPaul » Tue Jun 15, 2021 12:23 pm

The two power tubes are 6L6GC.

The phase inverter is in V5, which is a 12AX7.

If you have been satisfied with your amp's sound, you should be able to check the brands of the old tubes and order those.

Keep the old tubes. If these new tubes do not fix the issue you can put the old tubes back in and save the new tubes until you do need them.

Side note that there is a post in the FAQ that explains what each one of the five 12AX7 tubes does in the signal chain.

viewtopic.php?f=19&t=2464#p20584
Enzo wrote:I find if the amp is working, that is a good point to stop fixing it.
James Paul's Peaveys
Decade, Classics, Ecoustic, Windsors, VYPYR, Triple XXX, XXL, VKs, Bandit, JSXs, VIP, Piranha and a Penta.

Frankentar
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Re: Help!! Peavey 6505+ 112 combo cuts off

Post by Frankentar » Tue Jun 15, 2021 1:12 pm

Thanks, JamesPaul! I’ll let you know how it all shakes out, once I’ve got the new tubes in.
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Princeton Reverb, Peavey VK 112, Roland Blues Cube Hot

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JamesPaul
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Re: Help!! Peavey 6505+ 112 combo cuts off

Post by JamesPaul » Tue Jun 15, 2021 7:59 pm

It will be a great outcome if the new tubes resolve it. They are accessible and easy to change. Please do let us know!
Enzo wrote:I find if the amp is working, that is a good point to stop fixing it.
James Paul's Peaveys
Decade, Classics, Ecoustic, Windsors, VYPYR, Triple XXX, XXL, VKs, Bandit, JSXs, VIP, Piranha and a Penta.

Frankentar
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Re: Help!! Peavey 6505+ 112 combo cuts off

Post by Frankentar » Wed Jun 23, 2021 4:32 pm

Hey, just wanted to say that the recommended power-tube replacement (along with switching-out the phase inverter 12AX7) worked! -- At least so far 8~) !!

The amp sounds great and the fix was easy. So... thanks JamesPaul and others!

[btw -- I don't have a 6505+ after all, but rather a plain ol' VK 112 50-watt. Live and learn.]

Frankentar
Pacific Northwest
Part-time builder of Fender-type guitars for personal consumption




Princeton Reverb, Peavey VK 112, Roland Blues Cube Hot

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