Deluxe Reverb rectifier tube

[Prairie Dawg]

Why not 5Y3s? I've got a couple DRs to work on, and I've got some lovely brown base military surplus 5Y3WGTs looking for a home.

I've read the stuff in the tube manuals about the capacitance limit on the input, but how much difference does that really make?

[Jazz P Bass]

I think the capacitor spec is because of current draw at startup.
The datasheet for the 5Y3 calls for 20uf.
Older tubes will probably withstand more abuse than the new stuff tthat is being manufactured.

[MWJB]

The Russian "so called" 5Y3 is pretty sturdy, has a slo warm up & handles more current than NOS 5Y3...BUT it delivers B+ voltage not that far off a GZ34. The data sheets are way conservative, Fender have used over 32uf since the late 50's with 5Y3 rectifiers, they'll take 100uf. A 5Y3 might last fine in a DR, but it will cut headroom (may/may not be desirable). If you're worried about high B+ in the DR's then maybe use current production 6V6 with higher voltage handling.

[Prairie Dawg]

I think you're both right.

This happens to be a blackface DR that I'm reviving-seriously bodgered by a repair shop who shall remain nameless. They installed diodes, slopped silicone sealer in the rectifier tube socket, installed a mix of 33uf and 47 uf filter caps (NTE) and bodged a couple resistors together because they didn't own a 10k dropping resistor. Two of the NTE capacitors failed, because this thing was running at about 480 volts.

I stripped all the junk out and installed 22uf F&Ts and some proper dropping resistors. With a Ruby GZ34 the plate voltage runs at about 440 and with a 5Y3 it's about 430. I have a bunch of really nice military surplus brown base 5Y3s.

Not really stoked about the Ruby GZ34s, as one was shorted right out of the box.

[Chuck H]

Already covered here, but I have a couple of builds for customer/friends that have been using a 5Y3 and and a 40uf main filter for many years without issue. Just to offer some first hand about it.

[greekie]

I think you're both right.

This happens to be a blackface DR that I'm reviving-seriously bodgered by a repair shop who shall remain nameless. They installed diodes, slopped silicone sealer in the rectifier tube socket, installed a mix of 33uf and 47 uf filter caps (NTE) and bodged a couple resistors together because they didn't own a 10k dropping resistor. Two of the NTE capacitors failed, because this thing was running at about 480 volts.

I stripped all the junk out and installed 22uf F&Ts and some proper dropping resistors. With a Ruby GZ34 the plate voltage runs at about 440 and with a 5Y3 it's about 430. I have a bunch of really nice military surplus brown base 5Y3s.

Not really stoked about the Ruby GZ34s, as one was shorted right out of the box.

Next time you should definitely take a picture of a mess like that. I've seen pictures of the innards of amplifiers modded by people who are very hyped on the forums online. I think it's healthy for the business to expose bad work. Not necessarily by name, but at least get a picture of it and tell your customer not to go there again. We all suffer, when some tech does a bad job.

Jake

[Prairie Dawg]

the link between the two capacitors on the left of the picture fell out as well, leading me to think that the single 47 uf 450v cap was taking the full brunt of a measured B+ of 477v.

[Chuck H]

Nice. FWIW I've known those old black fiber boards to go conductive when botched up like that. It's happened to me once and I repaired another that came to me with the problem. So you may want to just poke a meter into the board here and there to see if you get a voltage reading.

[Prairie Dawg]

I took your advice. I fired up my old trusty Triplett VTVM and set it to read in megohms. The needle didn't budge. I may try my resistance tester to see what that turns up-it reads in thousands of megohms and puts 1 kv on whatever it touches. No current though. I mainly use it for evaluating stuff for high resistance shorts.

[Chuck H]

Aaah, but sometimes it's not just a rote resistance. The application of HV seems to excite the issue. I just poke the red meter around on the board checking for voltage to see if there's a problem.

[Prairie Dawg]

So you're more or less looking for stray voltage bleeding off from the live components then. Not surprising, really, if the cap is spraying electrolyte wet steam that it could make the board conductive. Good catch.

As it happened I had the chassis on the bench and powered it up and the one cap let out of a cloud of stuff that smelled worse than Stan Wisnowski a couple hours after Mrs. Wisnowski served up stuffed cabbage last Friday night.

[1ampman]

Chuck H, I've replaced 3 Fender eyelet boards due to conduction, but haven't replaced the cap boards. What symtoms would you notice? What about the recticfier/bias board? Any problems with those? I'm sure at some point they go bad....

[Chuck H]

I'm sure ANY black fiber board can suffer from this. The Fender I replaced the board on was a Vibro Champ, so no seperate power supply or bias boards. The other amp was a Traynor Bassmaster. Some think it's strictly a moisture issue but I don't. Whenever I've seen it the amps were well cared for and not exposed to high humidity environments. It seems to happen somewhat random. Maybe certain boards with a higher amount of black pigment??? AKAIK all black pigment is "lamp black", which is a soot byproduct like that produced inside oil lamp glass. So it's carbon. Who the f@#k thought it was a good idea to use carbon as a pigment for a circuit board??? I marvel at the fact that these things are still sold as standard in kits and other after market premade and blank boards. I won't go near it for any of my amps. Mojo be damned.

[Prairie Dawg]

Well, I did ok on the leakage end of this deal, everything was fine. It's finished and the best part of it is, it's a 1964 Deluxe Reverb and I get to keep it and play it for a couple weeks before it gets picked up.

@Chuck, re the boards. Lots of good information about them in The Soul of Tone.

[Pedro Vecino]

With a Ruby GZ34 the plate voltage runs at about 440 and with a 5Y3 it's about 430. I have a bunch of really nice military surplus brown base 5Y3s.

In the last DR I've seen, with Mullard GZ34, 440V. With RCA 5Y3, 400V.