vox berkeley super reverb

[Zephedone]

Rp , The voltages I had posted just scared me . The plates were glowing red or orange , I'm a little color impaired . Anyways , i went out to the shop to return the circuit to original and in order to do that I had to remove the connection from the rectifier to the first node . So I just alligator clipped a 200 ohm resistor in and this is what I measured . 277 / 267 / 168 for the three nodes of the power supply . On the output tubes I measured 271 vdc on the plates 266 vdc on the screen grids 9.1 vdc on the cathode .081vdc on the input grids . I had a few old wire wound resistors that I pulled out of an old Hammond organ amp laying on the bench , one at 30 ohms and the other at 200 ohms . I tried both and the 30 ohm didn't do much . I'm wondering if I should just solder it in and be done .

[LeeMo]

Maybe you could hack together a VVR to bring your voltages down to match the schemo.

LeeMo

[Zephedone]

Well I don't know what happened but the voltages are magically within reason . I was ready to solder in the big wire wound resister after clipping it in and running the amp , letting it sit while still turned on , playing my guitar thru it for a good 45 minutes to see if the resister would work . Pulled the resister clipped the rectifier back to the first filter cap and the voltages are good . Within 10 or 15 volts of the schematic . I just fired it up again and let it sit at idle for maybe 30 minutes and they are still good . I fixed it ?!??!? I don't know . I'll fire it up again and if the voltages are still good I'm going to put it all together and go with it . Here are a few more pics . Cleaned all the pots with the air compressor and some electronics cleaner from the radeeo shak . One of the indicator lamps , the "on" lamp , was not working and I got lucky as I was able to clean up the base of the bulb and it lit up after re-installation . Oh yeah , one more thing . I notice a loud pop when I turn it off . There was a .047 signal cap wired to ground off of the line reverse switch on the primary side of the PT . I disabled the line reverse and the accessory AC shown on the schematic . I would guess this has something to do with the pop I am hearing . Anyone have any suggestions ?

[rp]

Nice.

Well I don't know what happened but the voltages are magically within reason .

Solder intermittent? Were you rolling output tubes?

Hate to bring this up as it's a big PITA but all those blue bypass caps should be changed. They are probably worn by now and the amp will perk up like new with a swap. Don't mess w/ the turds and ceramics however.

You got lucky on the bulbs, one's a 47 other is seriously oddball, but check out the red-stby / green-play circuit, it's cool, only amp I know of w/ something like it.

As it's working well maybe you should leave it but if you are going to play it flat out a lot I'd swap the 2W CC 120R Rk to 130W 5W sandbox type.

Now you need speakers. The old Rola ceramic 10s made that amp, not sure what would be the equivalent. Maybe Greenback 10s? Weber ceramic silver and/or blues?

Wish I could still find something old to restore.

[Zephedone]

Rp , I went ahead and changed out the bypass caps but left the 2W CC 120R Rk . If I can dig one up I will change it out though . My concern now is the pop when shutting down . Is this due to the so called "death cap" I have read about ? As far as voltages . The only thing I know that was different was that I neglected to plug in the reverb tank . At the second to last time I fired the amp up I realized this was not connected . The speakers look original and are Licensed by Jennings Musical Instruments , made in England according to the sticker on the magnet . You can see them in a pic on the first page . They look like Celestions to me . This is a number on the frame ; PO3LK .

[Zephedone]

A little more progress . A few comments . Vox grillcloth a total PITA ! Piping , ditto . I learned a lot from this . Mostly , do not offer to work on Vox . But , I like the look of this amp and am planning on building an amp with some of the Vox cosmetics .

[Zephedone]

The finished pics . I had a voltage problem that seemed to fix it's self . All of the measurements I took were with the reverb pan disconnected . I don't know if this had anything to do with it . Once the reverb was connected my voltages were right in line with the schematic . I replaced all of the filter supply caps and also the cathode bypass caps . The amp did sound really nice . I really liked the trem and reverb . I usually do not care for reverb but this one sounded nice . I also had to replace the reverb pan . I used a unit pulled from an L100 series Hammond organ . It measured about 170 ohms on the input and output . That is within a few ohms of what the vox pan measured . I replaced it because it was intermittent on one side . It seemed like the little coil was loose . I don't know if this is something I want to do again . On the Vox nameplates and the metal handle parts my girlfriend used a sharpie paint pen . New piping and pin striping all the way around . Eight new corners .