Vintage Ampeg V4/V22 resoration

[vampwizzard]

Hey folks! Ive been airing out an old Ampeg V4 head a buddy wants me to get in working order. Thing smelled like an ashtray.. dang smokers.

What I know:
that it's "not working"
it's missing its fuse cap. The holder is still there.
He wants to keep it as original as possible.
It was allegedly recapped but the external filter cap cans were left in place to keep the stock appearance

I can find a replacement for the fuse holder (expensive as hell of course). Anybody run into these before? Any big common problems?

[DummyLoad]

they have 600V+ to the anodes. bulky, heavy and a pain to work on with anything relating to the control PCB. replacement pots are unobtainable. fabricate new ones with Bourns w/ long buhing and 3 wires to PCB.

watch out for the speaker Z selector - it is a cheap slide switch that is prone to failing open and root cause of many OT demise. CHECK IT.

ditch the auxiliary AC stuff and series fuse nonsense. RE: the recap job, never trust anyone else's work.

some hi-rez pics of mine as-was when i bought it; shots 1-20 are as-was. 21-29 are of the completed repairs. mine came with a blown OT and a bad Z selector switch - it was purchased still in pieces and as literally a basket case. it had about 1/2 tube of silicone to hold a shoddy re-cap job in place - that was fun to chisel out... the polarity switch in mine is now a hole filler.   

https://www.dropbox.com/sh/q7oapfktll8reuy/AABqjTbuqgQBMderNOnyHOzIa?dl=0


--pete

[vampwizzard]

thank you! thats going to be a tremendous help. I wouldnt trust anything a tech in my area has done.. ive seen a lot of very bad things 

[sjwood3]

Amazing, I just ordered the parts from Fliptops to recap a V4 and a B15s.   Thanks for those pictures!  I'll follow this one closely.

[Bostom]

I just recapped and replaced failed/failing components on a '79 MV V4 and a '74 V2 this year. The PCB isn't that hard to access. there are plates on the tube side that are removable.  The pcb does get hot so I saw baked on flux. I used deoxit and a tooth brush to clean up, being careful of pcb pads that may have come off the board. I only encountered it once and gently superglued it back in place. I would clean all tube sockets and you may find you'll need to reflow some solder joints, I did. Pots are hard to remove and get to but not impossible to clean. +1 on the impedance switch. Do a proper deathcap delete. There are 3 multi cap cans chassis mounted and one mounted inside. The pcb is well labeled for component id on both sides of the board. I used http://www.vintageampeg.com/forum/ as a resource.  Schematic should be on the top chassis plate. If not this site has all of them. Use the one that best matches your actual circuit there are some subtle and more obvious differences. And above all be safe and careful there is very high voltage present in this amp.
Tom

[TubeGeek]

I have a VT-22 head in for servicing right now.


This will be my second VT-22 service job.  The first one was maybe 4 or 5 years ago.


They are beasts and not cheap to service either.  Caps alone make it costly.


Good luck with your job!