#1
I have a Peavey Classic VTX 212. It is a hybrid amp with two 6l6gc power tubes and a solid state preamp. The serial number says it is from 1985. I bought it this summer and it was working fine and sounding great up until recently. I turned it on one day and it started buzzing. The guitar would not come through and the volume did not effect the buzzing. I changed out the tubes, I have heard the amp is fixed bias so i just swapped the tubes. Nothing changed. So I opened it up. A capacitor in the power section looked bad so i checked it with a multi meter. The meter read that the cap was bad. I changed the cap. After that the guitar would come through but with static. After spraying things down with contact cleaner the amp worked perfectly for about ten minutes. when I put the amp back in the cab it went back to buzzing. This made me think the tube sockets were bad so I replaced them with new ones (the old ones were about 30 years old). Now it is still buzzing and i don't know what to do. The buzzing is kind of staticy and only when playing, it is not constant. I have tried other cables and guitars and it did nothing.
this is what it sounds like now.
this is what it sounds like plugged into the power amp in on the back of the amp.

Any pictures or recordings needed can be provided.

Any help would be greatly appreciated.
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Last edited by dylan08 at Mar 3, 2012,
#2
have you checked the wiring ftp, the input jack of the amp and any tantalum caps in the circuit as they are used to filter dc current that can cause hum in the signal path
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#3
i think the the input jack is fine because there is a high gain and a low gain one and the problem is on both. what is the wiring ftp? i dont have a whole lot of experience with working on amps.
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#4
That could be so many things. First place I'd look after the phono sockets would be the speaker connections. After that I'd be looking for dry joints on the board, especially the connections to the pots.
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#5
Quote by Cathbard
That could be so many things. First place I'd look after the phono sockets would be the speaker connections. After that I'd be looking for dry joints on the board, especially the connections to the pots.

i re-did some solder joints on the power board and it seems to be working fine. There is still a very tiny buzz but it is a lot better. I may do a couple more solder joints one the power board. Thanks for the help!
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#6
it is still sounding the same, re-doing some solder joints seemed to help a little but now it is sounding bad again. I plugged into the pre amp out and into another amp and it sounds fine. So i think the problem is in the power section. i checked some things with a multi meter and a resistor is not giving a reading at all. Does it sound like this could be a problem with a resistor? It sounds like the power tubes are failing but they are fine.

any ideas?

edit: also the volume used to be quite loud on zero and now i have to turn it up to about three to get any sound.
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Last edited by dylan08 at Mar 26, 2012,
#7
First thing to try is removing the tubes and plugging them back in again. If you have some contact cleaner spray some on the tube pins and work the tube in and out of the socket 3 or 4 times. Make sure they are seated properly and try again.
Gilchrist custom
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#8
I already tried contact cleaner. i am hoping it is an easy fix, but if i can't figure it out I might send it to a tech. could a capacitor cause this problem? one of the smaller caps in the power section reads that it is shorted but i don't know if i trust my multi meter because it is not in the greatest shape.
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Last edited by dylan08 at Mar 26, 2012,
#9
Cath is right, that could be a number of issues. Weak supply caps, dirty input jacks, dirty FX loop jack(s), partially fried output transformer, etc..
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Last edited by ConfederateAxe at Mar 27, 2012,
#10
Quote by ConfederateAxe
Cath is right, that could be a number of issues. Weak supply caps, dirty input jacks, dirty FX loop jack(s), partially fried output transformer, etc..

i am hoping i can fix it myself, but if i can't figure it out i may send it to a tech, that could spare me a lot of time.
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#11
Well, partially fried OT's are rare. Normally they either work or they don't.
Gilchrist custom
Yamaha SBG500
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Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
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#12
http://forums.peavey.com/download/file.php?id=6893&sid=7807bc01474a2248fde66e76388f4c8b

this is not my pic but the same amp. in the power section there are four big caps. On mine on of the smaller caps(black ones) according to my multi meter is shorted but it looks normal. My meter is old and i am not sure if i should trust it. does it sound like this could be my problem?
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Last edited by dylan08 at Mar 27, 2012,
#13
When you first touch a multimeter to a cap it should look like a short at first and then drop back to open circuit once it charges up. Make sure you discharge them first or you can blow up the meter. Ohm meters don't like being placed across live voltages.
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Yamaha SBG500
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Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
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#14
Quote by Cathbard
When you first touch a multimeter to a cap it should look like a short at first and then drop back to open circuit once it charges up. Make sure you discharge them first or you can blow up the meter. Ohm meters don't like being placed across live voltages.

all the others dropped back expect for one.
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#15
Replace it.
Gilchrist custom
Yamaha SBG500
Telecasters
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
My band