VH4 crackling noise when on - HELP!! -solved-

[geese_com]

So, my VH4 started making a crackling noise.

It happens when the amp is tuned on and plugged into the cab. A guitar doesn't even need to be connected to the amp for it to make noise.

I know the cab isn't the issue because the sound persists even when plugged into my Peavey 5150 4x12.

Is this a preamp tube issue?

I tried replacing several preamp tubes (one by one) with the only other spare 12AX7 that I have (Tung Sol) and the noise is persisting.

Please help since I have a gig on Saturday, August 11th!!!!

 

[MARK2C]

The input jack shorts to ground when no instrument is plugged in, so it most likely is a power tube or a power tube socket pin not making a good connection.

A. Clean the input jack with De-Oxit
B. Pull the center power tubes and see if the noise stops
C. If no, Put the inner two tubes back in and pull the outer pair
D. Look in the sockets for wide spread out pins. With the amp off and unplugged, use a
mini screw driver or dental pick and gently push the socket pins inward.


viva VH4 !!!!!!

 

[Peter Diezel]

Thanks MARK2C

DON`T FORGET TO UNPLUG THE AMP WHILE ADJUSTING ANY TUBE CLAMBS !!!

 

[geese_com]

Here's a youtube vid of the noise.

 

[MARK2C]

Here's a youtube vid of the noise.

O.K., still sound like what I said earlier. Now stop running the amp or you may blow a tube or tube fault fuse from an arc.

1. Unplug the amp
2. Remove all the power tubes and mark them with a marker 1,2,3,4 as there position in the amp
3. Take a jewelers flat head screwdriver or dental pick and push all of the pins towards each other just a bit to tention them. If you cannot get the driver or pick behind the pin, try getting it behind at the bottom of the pin and lean it forward. Basically, if you look at the tube socket and the contacts in the socket are flush against the walls, they need to be tightened.

Very simple maintenence and will repair the problem. The cause is rotating tubes too much out of the sockets and they spread. Especially prone to amps that accept every major power tube and someone decides to try every type !!!

I have had 5 Diezel VH4's and have had 0 failures since 1999. I had to do this same procedure in my 2007 VH4 because I went from EL34 to KT77 to 6550. Same noise, easy repair. Now I take two minutes to check the tention before I re-tube.

 

[geese_com]

Should I still clean the input jack?

Thanks

Here's a youtube vid of the noise.

O.K., still sound like what I said earlier. Now stop running the amp or you may blow a tube or tube fault fuse from an arc.

1. Unplug the amp
2. Remove all the power tubes and mark them with a marker 1,2,3,4 as there position in the amp
3. Take a jewelers flat head screwdriver or dental pick and push all of the pins towards each other just a bit to tention them. If you cannot get the driver or pick behind the pin, try getting it behind at the bottom of the pin and lean it forward. Basically, if you look at the tube socket and the contacts in the socket are flush against the walls, they need to be tightened.

Very simple maintenence and will repair the problem. The cause is rotating tubes too much out of the sockets and they spread. Especially prone to amps that accept every major power tube and someone decides to try every type !!!

I have had 5 Diezel VH4's and have had 0 failures since 1999. I had to do this same procedure in my 2007 VH4 because I went from EL34 to KT77 to 6550. Same noise, easy repair. Now I take two minutes to check the tention before I re-tube.

 

[MARK2C]

Not until after you tighten the tube pins.

 

[MARK2C]

This is what you will look for. Below, are stretched pins. If you look at pins 2 and 7 on the right socket, being so loose they caused the noise through the tube heaters.

 

[geese_com]

This is what you will look for. Below, are stretched pins.

Thanks for the pic. That is really helpful. PM me and maybe you can call me to talk me through it please?

 

[geese_com]

I can see that I have a bunch of pins that right up to the white part of the tube socket.

 

[geese_com]

Seems like an eye glasses screwdriver works pretty well also =)

 

[MARK2C]

That will work. Unfortunately, that is where I am now. I'll check in tomorrow to see how you make out. Just push the two parts of the tube pins in (towards) each other.

If you are doing it now, PM me your phone number.

 

[geese_com]

PM sent

 

[geese_com]

Well....it looks like this might be the problem:

 

[MARK2C]

Peter will have a time looking at the hum trimmer being at 3 Ohm. It should be two 100 Ohm resistors in paralell.

 

[Ventura]

MARK2C, you're a man on a mission.

What the hell's happening with this head? Where'd the OP buy it?

Simple concept is a re-tube.
MARK2C's advice is very sage.
The PCB looks messed with...and this begs the question, where'd this amp come from?

Hope it works out.

VH4's rule.

Mo

 

[geese_com]

MARK2C, you're a man on a mission.

What the hell's happening with this head? Where'd the OP buy it?

Simple concept is a re-tube.
MARK2C's advice is very sage.
The PCB looks messed with...and this begs the question, where'd this amp come from?

Hope it works out.

VH4's rule.

Mo

I bought the head used, but then had to get it retubed with KT77s because one of the tube fuses blew.

I took it into the local reputable amp tech. He looked at it and told me that the trim pot went the same time the fuse blew, so he replaced it. Apparently, he replaced it incorrectly per my discussions with MARK2C.

BTW MARK2C IS THE MAN!!!!! ABSOLUTELY AWESOME GUY!!!! I would like to thank him for all the help he gave me today regarding my amp.

Hopefully I can get things fixed before my gig tomorrow night.

 

[Ventura]

MARK2C, you're a man on a mission.

What the hell's happening with this head? Where'd the OP buy it?

Simple concept is a re-tube.
MARK2C's advice is very sage.
The PCB looks messed with...and this begs the question, where'd this amp come from?

Hope it works out.

VH4's rule.

Mo

I bought the head used, but then had to get it retubed with KT77s because one of the tube fuses blew.

I took it into the local reputable amp tech. He looked at it and told me that the trim pot went the same time the fuse blew, so he replaced it. Apparently, he replaced it incorrectly per my discussions with MARK2C.

BTW MARK2C IS THE MAN!!!!! ABSOLUTELY AWESOME GUY!!!! I would like to thank him for all the help he gave me today regarding my amp.

Hopefully I can get things fixed before my gig tomorrow night.

You buy the head off eBay or CL...?? What's its S/N?? I know of a few out in the market that were messed with and keep trading hands.

Mo

 

[geese_com]

I bought it off of a member here. I know that the guy who repaired it for me was the one who put the wrong component in because he gave me the trim pot he took out.

MARK2C, you're a man on a mission.

What the hell's happening with this head? Where'd the OP buy it?

Simple concept is a re-tube.
MARK2C's advice is very sage.
The PCB looks messed with...and this begs the question, where'd this amp come from?

Hope it works out.

VH4's rule.

Mo

I bought the head used, but then had to get it retubed with KT77s because one of the tube fuses blew.

I took it into the local reputable amp tech. He looked at it and told me that the trim pot went the same time the fuse blew, so he replaced it. Apparently, he replaced it incorrectly per my discussions with MARK2C.

BTW MARK2C IS THE MAN!!!!! ABSOLUTELY AWESOME GUY!!!! I would like to thank him for all the help he gave me today regarding my amp.

Hopefully I can get things fixed before my gig tomorrow night.

You buy the head off eBay or CL...?? What's its S/N?? I know of a few out in the market that were messed with and keep trading hands.

Mo

 

[MARK2C]

I feel that replacing those resistors solves the problem. These amps are tanks !!!

@ Poppa,

All the tube clamps were cleaned and tensioned. Tried new speaker cable, cleaned input jack, ran with both inner and outer tubes pulled. Looked at screen grid resistors and they are O.K., no browning or carbon. Ran in 6L6 bias position to be sure they were not over biased. The noise is consistent on all 4 channels. When I asked geese_com to adjust the hum trimmer we figured out it was removed.