5F6A popping fuses

[Smokebreak]

I got this build finished, fired it up and it worked fine for a few minutes. Turned it off/ on and gz34 flashed and popped a fuse. That was the only 3A SLO I had, so I put in 3Afast and things were fine(?). Went to radshack got 3A SLO and they're popping again. Put in a fast, and it's fine.
I was using known working tubes.
Plates originally were 460, trimmer was maxed out at 20ma, and before I could even fiddle with bias resistor, now my gz34 is only putting out 360, and bias, with various tubes, has fallen to 5mA. Neg bias V is fine at 220Ks, around -50.
Any clues?

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With 6l6s pulled, B+ back up to 450

[Reeltarded]

Killed it! What brand? I effing hate these tubes.

FB should blow.. weird.

[JazzGuitarGimp]

I'd say chances are pretty good the GZ34 is blown. What is the size of the reservoir cap? Did you leave it off long enough for the reservoir to fully discharge, but not long enough for the GZ34 to cool down?

[Reeltarded]

Yaya what Capt'n Lou saids. The mains cap was stiff..

Hey, what cap do you have there anyhow.

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That's what I'm thinking.. It was a freakin JJgz34. I believe they are notorious for this. Reservoir is 22s in parallel,so 40, but it did put a 100k5W bleeder across them...and yep I did not leave it off long enough, maybe 5 sec.
Rect is still putting out 360 though. How is that and how is that affected what 6l6s are drawing( still under 5ma)?

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I was still getting 460 of rect for a bit after the first pop too. After 4 pops is the rect just getting weaker? I thought those things were on or off

[Reeltarded]

Ummm.. do you have another GZ to swap in? Worried to say much else. Don't want to make you worry.. yet.

[JazzGuitarGimp]

I don't know enough about rectifier tube failure modes to make a statement, so I will say it seems to me that the GZ34 is not longer capable of passing much current. So when the output tubes are installed, and asking for 40mA between them, the GZ34 just can't deliver it. If your reservoir cap and the circuitry that follows can handle the additional voltage, you might try tack soldering a pair of 1N4007's over the GZ34 socket, remove the GZ34, and bring it up on either a variac or a light bulb limiter.

[JazzGuitarGimp]

It may also be possible that one or both of the 6L6's took a dive.

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Only in my gigging vibrolux, can't do that tonight. I do have a 5v4ga but read on tubedepot site these shouldn't be used in 5f6a. Not sure why though. They're both 2A

[Smokebreak]

I don't know enough about rectifier tube failure modes to make a statement, so I will say it seems to me that the GZ34 is not longer capable of passing much current. So when the output tubes are installed, and asking for 40mA between them, the GZ34 just can't deliver it. If your reservoir cap and the circuitry that follows can handle the additional voltage, you might try tack soldering a pair of 1N4007's over the GZ34 socket, remove the GZ34, and bring it up on either a variac or a light bulb limiter.

I do have a 610 tap on PT so I'll wire that with SS diodes and see what happens. I also have plenty of 5u4 and my PT is 3A heaters rating that can drop in eh?

[JazzGuitarGimp]

Possibly, if it's a 5U4GB. I would still employ a light bulb limiter until you know for sure the output tubes are okay.

[JazzGuitarGimp]

It might also be a good idea to visually inspect the three octal tube sockets for carbon tracks, both on top of the socket and on the bottom.

[Smokebreak]

Ok with lower voltage taps and SS diodes I'm back in business with 420 plates and loud clean amp . Fiddle players don't need no sag anyhow! I lost the GZ and 1 6L6. Now I gotta get the bias right. Maxed out at 12mA now. Still have the fastblow in