Finished BUT octal tube POPS when touched/jiggled [resolved]

[Jsin]

You were right - soldered now.
So - do I proceed like maybe that fixed things?
Resistance test - glow test (no fuse blow) - voltage test?

<<update>> did ohm test, passed. Put tubes in, new 1A fuse, plugged it in, turned it on, and blew the fuse....

[Paul Birkeland]

You'll have to try the 3A fuse and see what sizzles.

If you have more 1A fuses, you can try powering the amp up with no tubes.  I'm 99% certain that your fuse will still blow, but it's another test that could be performed.

[Jsin]

Will try the 1A fuse without tubes first - and if it still blows I’ll throw the 3A in and see. Should the 3A test be done with the tubes in?

Thanks.
J

[Paul Birkeland]

Sure, go ahead and have them in for the 3A test.

[Paul Birkeland]

That lead poking out at 19 could definitely be shorting the HV winding.  Please do trim that first before running the 3A fuse. 

[Jsin]

Do you mean the lead at 20L that is pointing down toward the base plate?

[Paul Birkeland]

This is what I see that could be a short that would blow the fuse immediately if those two pieces of metal are touching, or could move around and touch each other.

[Jsin]

SUCCESS!!!
I crimped that wire right to the board, resoldered the LEDs and a couple of other dull looking spots, did an ohm test then - moment of truth - 1A fuse and the tubes glowed. Flipped it over and both LEDs lit! Voltage test was spot on.
Just listened to Kind Of Blue on my Stein 6xx and it sounded magical!!!

1,000 thanks for all the help. Very excited to listen for awhile and then take a run at Speedball.

[raindownthunda]

I have a related question regarding a popping noise I have experienced in my new BHC build twice now with two different tubes. Both times the tubes worked fine for 5-10 mins and then I saw a bright white "spark" inside the tube. The first time this happened was with a WE 421a and the spark stayed in the same position on the plate. Both times the white sparks were accompanied by LOUD popping noises, IIRC only out of the right channel. At first I thought this might be a bad tube as I had tried 5-6 other output tubes with no issue before these... but after the 2nd time it happened with a different tube that had been tested as a good tube by the seller, I got suspicious it could be the amp.

I re-inspected the wiring and noticed that the octal socket wiring had moved a bit due to tube flex (and poor judgment on my part) so that two of the octal socket bare wires were VERY close to touching between pins 2 & 3. I am wondering if those wires were close enough to touching that this would explain the white spark on the plate accompanied by LOUD popping?

I've rewired the pin 2 & 3 wires so they are definitely not going to touch. I also reflowed a few solder joints at the same time, including the grounds for the headphone output. So far I've run both of the tubes I experienced issues with for 25+ mins each with no sparks/popping. I have PTSD from wearing my headphones when the popping happened, so I want to get your input on whether or not the issue I experienced sounds like faulty wiring that has now been fixed, OR if it could still infact be bad tubes that spark/pop very intermittently. I would hate to get rid of nice tubes that are perfectly fine. I have heard about tubes "arcing" but don't know if the issues I'm having sound like arcing.

Attaching a pic of the "white spark" glowing on the right plate of the WE421a. It was pretty bright (camera did not capture the brightness very well). Thanks in advance!

[Paul Birkeland]

It would be hard to say without seeing how close the wires were before, but if pins 2 and 3 on the octal socket touch, that's not a good situation!