JJ cap can wiring

[jojokeo]

I'm having a bit of a brain fart and want to ask prior to wiring:
I have an old Ampeg V2 in for service. I am going to re-cap but for the A and B nodes I need to series wire two caps for each (each node is close to 600v). I have a couple of JJ cap cans each with the usual 2 positive leads and sharing a single neg lead. (Yes, they will also have two 100k/2w to distribute the power equally). I don't think that the cap cans can be utilized for this correct?

[PRR]

Not the right cap.

These days a good path is a small board and "snap caps". They stand upright on a PCB (but you can snap into holes in Doug-board and solder to the leads). These caps are THE way to build most non-small DC supplies, up to welders, and are fall smaller than the big cans we used in the 1970s.

[jojokeo]

Thanks PRR, I didn't think so. I will also include something else that I also don't think will work either but I'll throw out the (bad) idea anyway. This doesn't seem that it would work even if I wanted to create two nodes that are for plates and screens both - still a "no go" sharing parts???

Do you have a link of the "Doug-board"?

[DummyLoad]

you cannot use all 4 sections as both A & B rails. see photo how i revamped a V4 (same amp 2x power). you can use the lower 2 section as 1/2 of the B rail if you attach a separate cap as the upper cap - see attached schema for one approach.


--pete

[DummyLoad]

V4 pic.


--pete

[jojokeo]

Thanks Pete! That's almost exactly what I'm doing with tag strips and I have the 100uF "snap caps" on hand, no cans for this one. One of them (the 80uF/80uF) fried pretty good. I'm surprised the B node series caps don't have the equalizing resistors on them and they don't show on the schematic either? The uF values don't match the schematic either but it does seem original due to the insulating washers? However someone did replace the preamp cap can but did a horrible job by using silicon to hold it in place with the one single neg lead bent inwardly. It came right off in my hand while straightening the tabs. I'll get a picture or two when it's complete.

[DummyLoad]

a horrible job by using silicon to hold it in place

i received mine in similar condition + 1/2 primary of the OT was blown + the reverb tank needed repair + the speaker Z selector switch was fried (center 8ohm): i suspect that's what took out the OT. check that cheesy slide switch on yours.

you're going to love the tone stack, headroom, and the reverb of that V2.

--pete

[DummyLoad]

another shot. they did work...i was just disgusted and ripped it all out.

-pete

[jojokeo]

the speaker Z selector switch was fried (center 8ohm): i suspect that's what took out the OT. check that cheesy slide switch on yours.

Here's the SOB down on the r of 2nd pic

[jojokeo]

Inside these are strikingly similar. The three 12ax7s tested weak, poor, and no good. The 6CG7, 12DW7, and 6k11 were all iffy and weak as well. The only tubes that tested strong were the 12au7 and power tubes. I'm hoping to finish up the filter caps tonight?

[DummyLoad]

not surprised about the 12AX7 and the 6CG7. the 6CG7 runs HOT, really hot - it's the reverb tank driver and it's running as a R-C coupled ckt. the 6K11 is thankfully not as hard to find as the 6C10, nor as pricy. there is a ebay seller that has a replacement PCB for the echo board of you want to use more common current production tubes - e.g., get rid of the 6K11: link below.


https://www.ebay.com/itm/Ampeg-V2-V4-VT22-VT40-Retrofit-Rev-2-Printed-Circuit-Board-/271878303072


happy hacking, jo!


--pete

[jojokeo]

Thanks for that & the helpful info but it’s got some impatient guys demanding her back ASAP. It broke down a bit in the middle of recording, the worst possible time.

[jojokeo]

Cap cans replaced... if one pre-fabs the job prior to installation things go much easier inside the chassis.