Help - BV120H (Crate BlueVoodoo 2nd Gen) - Intermittent Sound

[trip]

Hey guys,

I just picked up ANOTHER Bv120H for 50 bucks. (The second model, still blue tolex'd but the black faceplate and non-script lettering)

This one's got it's own issue.

Guy said he brought it to a tech who said it was the tubes. (Which kinda made sense)

The volume will just... disappear completely. It will come back after a while of waiting, or if you switch the channel sometimes. It seems to happen less frequently the longer the head is on.

First thought, power tubes (I still don't really know the symptoms of when they go bad since I've never really had them fail on me before) - so i ran 2 from the quad in v2 and v3, problem persists. Tried the other two, same. Tried another pair of known working tubes, same.

Inb4 I haven't opened it up yet to take any readings, what is a likely or common cause of volume jutting out and returning?

Volume does not make a difference, so it's not vibration based as far as I can tell. When i swapped to another set of tubes it did start to fade out but i'll chalk that up to those used power tubes. The good pair sounded awesome, and then literally just goes silent, and returns if I continue to play for a bit.

Common causes?

Could a faulty pre amp cause this issue? I have yet to roll those pres as a solution, just getting ideas for when I start troubleshooting.

Thanks!

[glebert]

I know the Crate Vintage Club tube amps had issues with the channel switch button and/or optocouplers(?). Don't know how much the VC amps have in common with the BV ones. Does this amp have an effects loop that you can test the preamp and power amp separately using known good amps?

[Enzo]

They are all made in the same factories from the same materials and were designed by the same people. It is unlikely the problem has to do with the model.

Sound cutting out? First explore all the jacks with cutout contacts. That means if there is a headphones jack that can turn off speakers. Or a FX return jack, or an insert jack.

I might believe ONE power tube fails off and on now and then, but ALL FOUR? And at the same time??

[trip]

They are all made in the same factories from the same materials and were designed by the same people. It is unlikely the problem has to do with the model.

Sound cutting out? First explore all the jacks with cutout contacts. That means if there is a headphones jack that can turn off speakers. Or a FX return jack, or an insert jack.

I might believe ONE power tube fails off and on now and then, but ALL FOUR? And at the same time??

As I've learned with tubes that should be very unlikely. Thanks for the tip, i checked all of the jacks, turns out I thought it was the issue but it wasn't.

Looks like the preamp tube furthest to the left, V4 if you count closest to input as v1, I think it has a cracked/cold solder joint, bad socket, or something there is shorting. Thinking it's just a bad solder joint, because if i wiggle the tube around/apply pressure at the right spot the sound comes right back. I noticed it as the tube filaments looked like they lost voltage when the sound cuts out (just the v4 pre). Tried other tubes, cleaned the socket with cc, still can be induced/resolved by giving the socket some wiggle. Next step is to open it up and look (the last bv was a cracked solder joint right along the iec, and i assume poor soldering/age is a common occurrence) - I'll be pretty happy if that's all it is, but changing a socket sounds fun too!