Peavey 6505+ Problem

[colynomial]

Hi Guys,

I'll make this as brief as possible.

I own several guitar cabinets but keep them in storage since I live in an apartment. Thus, I grabbed a couple of small bookshelf speakers just to use for practicing with my amp. The speakers are both 8 ohms, and rated for 100W. I plugged them both in parallel to my 6505+, set the amp impedance to 4 (8/2) and played for probably 2 hours today. Sounds surprisingly less awful than I expected and seemed to be fine.

Then tonight, I turned the amp on it's side (I'm sure this is irrelevant but who knows) to fit it under my desk and played for maybe 20 minutes, then set my guitar down leaving the amp and standby on. About 3 minutes later, I came back to hear a kind of oscillatory humming from the amp so I turned off the standby switch waited a few seconds and turned it back on. When I turned it back on, there was a quick "chirp" followed by silence.

Now one of the middle 2 power tubes is off. The power LED still lights up, but not the standby LED. I also checked the main fuse and it appears to be fine.

So question 1) any thoughts on what I might have blown and how I could go about fixing it (i.e. can I just swap in a new set of tubes) and 2) is there something about the bookshelf speakers that might cause this to happen again in the future? I figured they couldn't be any worse than using something like a load box but maybe I'm wrong.

Thanks in advance.

 

[guitarguru777]

Sounds like you blew a fuse in the power section. Happened to mine. There are 5 more fuses INSIDE the chassis of this amp other then the one on the outside. IF YOU DONT KNOW WHAT YOUR DOING DO NOT OPEN THE DAMN AMP! IT CAN KILL YOU! Take it to a tech, don't fuck with it or you will end up like me and blow the entire rectifier section of the amp and then it will cost MORE to fix. Get it to a shop NOW!

https://plus.google.com/photos/1018...5694187433360619202&oid=101853091679154524394

Thats what happened to mine when I decided to keep fucking with it! DONT DO IT!

 

[colynomial]

Cool, thanks for the advice. I've changed tubes before but never the power fuses. Is there some kind of latent charge stored in the capacitors even after the amp is unplugged that would cause it to blow like that?

I've got a good guy I use for amp repairs so I'll just let him do it.

I'll run the bookshelf speaker setup by him as well and see what he says. Doesn't seem like it should be a problem but who knows.

Thanks,

-Colin

 

[TheWinterSnow]

Cool, thanks for the advice. I've changed tubes before but never the power fuses. Is there some kind of latent charge stored in the capacitors even after the amp is unplugged that would cause it to blow like that?

I've got a good guy I use for amp repairs so I'll just let him do it.

I'll run the bookshelf speaker setup by him as well and see what he says. Doesn't seem like it should be a problem but who knows.

Thanks,

-Colin

By one of the tubes not on, do you mean doesn't have an orange glow? Would seem most likely that the filament/cathode of that tube shorted out but if it still does glow but doesn't have a slight blue hue if the other tubes have it, then most likely the screen grid resistor went out as the tube was failing.

Residual charges won't break an amp, and since you left it on, with the standby on, all High voltages were present in the amp, standby only kills power to the screen grid, effectively making the power tubes permanently in cuttoff, which they also do during normal operation. Also as for residual charges, all modern amps, the 5150 series amps included have bleed off resistors that virtually never fail, if you turn the amp off, all voltages are gone within about 30 seconds. Again the charges/being on doesn't damage anything that would cause what you would describe, failing electrolytic caps on the high voltage would take out the mains fuse.

More than likely, the heater filament fuse went out, based on your description. Same think that happened to Guru, except the fuse didn't go, it took out the filament biasing resistor, I think it was from shorted/faulty power tube IIRC.

 

[Drummerrrrr?]

Sounds like you blew a fuse in the power section. Happened to mine. There are 5 more fuses INSIDE the chassis of this amp other then the one on the outside. IF YOU DONT KNOW WHAT YOUR DOING DO NOT OPEN THE DAMN AMP! IT CAN KILL YOU! Take it to a tech, don't fuck with it or you will end up like me and blow the entire rectifier section of the amp and then it will cost MORE to fix. Get it to a shop NOW!

https://plus.google.com/photos/1018...5694187433360619202&oid=101853091679154524394

Thats what happened to mine when I decided to keep fucking with it! DONT DO IT!

What did you do?

 

[TheWinterSnow]

I re-read the OP and took a look at the schematic. With the Standby LED not coming on the only way for the to happen is if the standby switch broke or the high voltage rail's fuse blew out.

Oh and when you laid it on its side it caused the electrons to fall out.

In all seriousness though, get it checked out by a trusted tech and no the speakers could not cause damage like that, if the speakers were damaging the amp, you would smell transformer winding enamel burning and the Output Transformer would be as hot if not hotter than the tubes. The only way that usually happens is total speaker failure or using the amp continuously with no load.

 

[colynomial]

Thanks guys. Yes, one of the tubes did not have an orange glow.

I'll get it to my amp guy and post an update when I know what went wrong. Hopefully it's not too serious! :S