6505 hum

Gnash · 10th March 2008, 02:34 AM

I have this annoying hum coming out of my 6505 head. I bought it new, had the bias mod, and toured with it. Sometime during the tour the "hum" started. I've had 1 pre tube in V1 go bad, but that's it. I've checked all my cables, swapped all the tubes in and out, same hum. It's like a "60 cycle hum" I guess. It gets real loud for me since I use a Maxon od808 in front, and have the gain at 5 on the red channel. I switch to the green channel, set quiet or clean, in between songs to get rid of the hum. Since it's still under warranty, I guess I'll send it to Peavey.

I love this amp's tone, and I could never part with it, but do you think Peavey will give me shit for having the bias mod done? Anyone have this symptom with their 5150? I'm guessing I have a bad transformer or something.

Pfhuck · 10th March 2008, 06:18 AM

I purchased an old 5150 second hand a couple of years ago. $400! Couldn't resist the price!!!

Anyhow.

It was pretty beat. Needed a change of power tubes and some cosmetic TLC.

I gigged ALOT with it for a year or so, and then the HUM started. It would come and go as I "knocked" on the top of the head.... Loose connection or bad tube was the first thing I thought...

So... I pulled the chassis out and blew out all the dust, reseated all the ribbon cables and molex connectors, checked the grounds and PCB mounting to make sure they were all still FIRMLY connected to the chassis, reseated all the tubes.

And then fired it up before putting it back in the "head".

All was good! Put the chassis back in the enclosure, and voila! Still going strong!

Knock on wood.

I would imagine that any mods would void your warranty.

If your amp head is rattling around in a vehicle while on tour and/or getting ab-used at gigs as mine was. It probably just needs some TLC.

Worked for me anyways.

Laters,
Pfhuck

P.S. - If you remove the chassis from the head, DO NOT touch the PCB or tubes while it is powered up. Unless you KNOW what you are doing of course... It might

Gnash · 10th March 2008, 12:01 PM

Yeah, even though it was in a well padded road case all tour, it was bouncing around in the ****in trailor so something had to get "jarred." I need to look up an amp tech in my area, I guess. He can undo the bias deal, and then redo it maybe.

e ****in amps.

6strings · 11th March 2008, 02:02 AM

Quote:

Originally Posted by Pfhuck

P.S. - If you remove the chassis from the head, DO NOT touch the PCB or tubes while it is powered up. Unless you KNOW what you are doing of course...

Don't touch the anything internal even if it's not powered up or plugged in either. You need to know how to properly drain the capacitors or else you could get a lethal dose of voltage.

Try swapping some tubes out (or around). Maybe you'll get lucky and it's a cranky tube?

Gnash · 11th March 2008, 07:19 AM

Thanks!!!!!!! I was just reading another thread about draining capasitors (which I have no clue how to do). Could have been a dead slut! I've been through the tubes. I wish I could have the dude who modded it look at it, but he's 1000 miles away! I'm gonna have a tech, here in KC look it over. Anyone know an amp tech in the KANSAS CITY area?

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10th March 2008, 02:34 AM	#1
Gnash Gear nut Join Date: Jan 2006 Location: Warsaw, MO Posts: 88	6505 hum I have this annoying hum coming out of my 6505 head. I bought it new, had the bias mod, and toured with it. Sometime during the tour the "hum" started. I've had 1 pre tube in V1 go bad, but that's it. I've checked all my cables, swapped all the tubes in and out, same hum. It's like a "60 cycle hum" I guess. It gets real loud for me since I use a Maxon od808 in front, and have the gain at 5 on the red channel. I switch to the green channel, set quiet or clean, in between songs to get rid of the hum. Since it's still under warranty, I guess I'll send it to Peavey. I love this amp's tone, and I could never part with it, but do you think Peavey will give me shit for having the bias mod done? Anyone have this symptom with their 5150? I'm guessing I have a bad transformer or something.

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10th March 2008, 06:18 AM	#2
Pfhuck Gear nut Join Date: Nov 2004 Location: Lincoln, NE Posts: 78	I purchased an old 5150 second hand a couple of years ago. $400! Couldn't resist the price!!! Anyhow. It was pretty beat. Needed a change of power tubes and some cosmetic TLC. I gigged ALOT with it for a year or so, and then the HUM started. It would come and go as I "knocked" on the top of the head.... Loose connection or bad tube was the first thing I thought... So... I pulled the chassis out and blew out all the dust, reseated all the ribbon cables and molex connectors, checked the grounds and PCB mounting to make sure they were all still FIRMLY connected to the chassis, reseated all the tubes. And then fired it up before putting it back in the "head". All was good! Put the chassis back in the enclosure, and voila! Still going strong! Knock on wood. I would imagine that any mods would void your warranty. If your amp head is rattling around in a vehicle while on tour and/or getting ab-used at gigs as mine was. It probably just needs some TLC. Worked for me anyways. Laters, Pfhuck P.S. - If you remove the chassis from the head, DO NOT touch the PCB or tubes while it is powered up. Unless you KNOW what you are doing of course... It might

10th March 2008, 12:01 PM	#3
Gnash Gear nut Join Date: Jan 2006 Location: Warsaw, MO Posts: 88	Yeah, even though it was in a well padded road case all tour, it was bouncing around in the **in trailor so something had to get "jarred." I need to look up an amp tech in my area, I guess. He can undo the bias deal, and then redo it maybe. e **in amps.

11th March 2008, 07:19 AM	#5
Gnash Gear nut Join Date: Jan 2006 Location: Warsaw, MO Posts: 88	Thanks!!!!!!! I was just reading another thread about draining capasitors (which I have no clue how to do). Could have been a dead slut! I've been through the tubes. I wish I could have the dude who modded it look at it, but he's 1000 miles away! I'm gonna have a tech, here in KC look it over. Anyone know an amp tech in the KANSAS CITY area?