6505 hum

G

Gnash5150

Lefty
My 6505 just hums like crazy through each channel, and it gets louder, of course, as the gain goes up. I know it didn't have the hum before I started a tour. Somewhere in the middle of the tour the hum got loud. I've ben through all the cables, swapped tubes, still has the hum. I had the bias mod right after I purchased it new, and the only problem I've had before the hum was a pre tube in V1 went bad. I haven't had a tube problem since. I use a Maxon OD808 in front, and the amp is just not usable in the studio. I love the tone of the amp, and I just couldn't bear to part with it, but I may have to send it to Peavey( It's still under warranty) Will they give me shit because I had the mod? My guess is that I have a transformer problem?:confused: Anyone else have/had this symptom? Thanks
 
I'm guessing modding it would void the warranty. I'll assume that you've tried a different guitar cable and a different guitar.

This might sound really stupid, but have you tried moving it? Does it still hum if it's somewhere else in the room, or in another room maybe? Have you tried a different power outlet?
 
Yeah, I've tried everything. I used to think it was, ya know, the power at all the dump venues giving me interference, but the hum is still there. I've tried everything. Guitars, cables, cabs, tubes, pedals, outlets, rooms, cities, countrys, same hum. Noise gates don't work. I'm gonna get inside it, and look around, since I've voided the damn warranty. It's weird, but my other guitarist's amp, a Mesa Mark IV head, did the same thing, but not tho the extent of mine. It's bad.
 
i doubt seriously that it's the tranny as you suggest... much more likely is the supply filters... although they generally dont go out on a relitively new amp... but i would start there... next check for bad connections to ground... perhaps something was shaken loose while you were touring... i've never worked on that model so cant say for certain but one thing peavey used to do was run multiple ground plains that were tied to the chasis through the standoffs that hold the board so check that they're tight... good luck...
 
How do I drain the caps in my 5150? I want to look into my amp, but I don't want to get fried! I'm just looking for loose stuff. This hum is bad.
 
although some dont like this method i find no problem with it or any reason not to use it.... when your done playing it turn it off without useing the stand-by and hit a big chord... it'll do weird fade out and they'll be down... now take it outta the case an flip it over... you should see the filters now... and just to be extra safe take a wire and ground it and tap the filters connections a couple of times... that should take care of any little residual charge that wouldnt have hurt you but mighta made ya piss your pants... good luck...
 
Let me explain it a little better. Thanks for you post, dude. It's definately something internal in the FX loop causing the hum. I've thouroughly tested several different cables/pedal combos/batteries. I've tested every tube in every position. I once thought it was my 9 volt "dc brick" supplier, but I have since ruled that out. The hum is GONE, if I ihave nothing plugged into the fx loop send and return jacks. As soon as a plug gets near the return input jack (just touching the jack or even halfway plugged in) the hum starts. It sounds like a "60 cycle hum"?? It's just real loud. Once again I have tested several different cables/pedals/with and without the dc power brick. It's definately in the amp. I'm just running with no delay (fx loop) for now.:( Thanks for any help!
 
arcaxis said:
Take a straight guitar cable and run that from the send to return jacks. If you get no hum and you still have good signal from a guitar plugged in the front end, it's not necessarily your amp with the problem, it's more likely something amiss in your effect, its cable, or grounding.
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And if it hums in that configuration, it's probably a bad ground on either the cable or one of the jacks. :)
 
It's the jack. I've finally found a tech, and it's getting a full service "look through." I just don't have enough knowledge to go poking around in a tube amp. Man, I've I had some strange issues for a brand new amp. I've had a preamp tube go out in the first two weeks, and now this. I would have sent it in to Peavey, but I had to tour with it right after I bought it, and have voided the warranty with the bias mod. Oh well, it's my baby now. Thanks for everyone's help!
 
dementedchord said:
although some dont like this method i find no problem with it or any reason not to use it.... when your done playing it turn it off without useing the stand-by and hit a big chord... it'll do weird fade out and they'll be down...
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Some don't like this method because it does NOT drain all of the caps storing high voltage. The only good way is the sure way, which is to discharge to ground, check with voltmeter.
 
Gnash5150 said:
Yeah, Dementedchord, you took all my chicklets, and now you wanna fry me!:eek:
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sorry dont remember why i negged ya... think it was a different thread where you started to go off on someone for no reason....

as to frying you... believe me that wouldnt have done it... and it is a time tested method for draining caps... sure going through a resistor will be less "exciting" but it's no big deal... and it does drain most of the cap... the little bit it doesn't is from subsequent stages draining back towards the primary stage... and if you reread my other post i did say to check them for residual... tube amps generally dont store much long term wise anyway... solidstates can hold for a long time though... i worked on a crest amp once that i turned off friday as i left the shop and got bit by it on monday morning...
 
dementedchord said:
sorry dont remember why i negged ya... think it was a different thread where you started to go off on someone for no reason....

as to frying you... believe me that wouldnt have done it... and it is a time tested method for draining caps... sure going through a resistor will be less "exciting" but it's no big deal... and it does drain most of the cap... the little bit it doesn't is from subsequent stages draining back towards the primary stage... and if you reread my other post i did say to check them for residual... tube amps generally dont store much long term wise anyway... solidstates can hold for a long time though... i worked on a crest amp once that i turned off friday as i left the shop and got bit by it on monday morning...
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The tubes stop passing signal when the heaters cool down, and the filter caps can still have quite a bit of charge left on them at that point. Drain your caps to the chassis through a resistor.
 
they dont cool that quickly.... dont want to use the technique???? dont... but dont kid yourself either... oh well must be a slow day if we can argue about this... later gunn...
 
dementedchord said:
they dont cool that quickly.... dont want to use the technique???? dont... but dont kid yourself either... oh well must be a slow day if we can argue about this... later gunn...
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No argument, it's just that the sure way to know that the caps are drained is to bleed them to ground. Your method may very well work or it may not; I'd rather know for sure. I bleed them to and then double check with a meter before I touch anything. I hate getting shocked.

Peace,
 
dementedchord said:
they dont cool that quickly.... dont want to use the technique???? dont... but dont kid yourself either... oh well must be a slow day if we can argue about this... later gunn...
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No argument, it's just that the sure way to know that the caps are drained is to bleed them to ground. Your method may very well work or it may not; I'd rather know for sure. I bleed them and then double check with a meter before I touch anything. I hate getting shocked.

Peace,
 
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