Lose Rythm 1 channel when hot

[jimmybcool]

I got a beautiful Boogie Mark IV in Maple cabinet. Love it. Lead tones to die for.

But tonight it started to have a problem. The lead channel still works. Rythm 2 still works. But Rythm 1 dies.

I let it cool and tried it again. Everything worked fine. For a while and then it repeated the problem.

I have spare tubes but it is not clear to me which tube would have this effect. Any ideas? Or is it more insideous than a tube?

 

[jimmybcool]

I'm talking to myself

OK, more information.

I have two Boogies and compared them side by each.

1) First the loss of the rythm channel is NOT due to heat. It is just intermittant.

2) Both rythm channels are at much lower volume on the one with the intermittant channel loss amp.

Conclusion - I have a tube shared by the two channels that is going kaput (the technical term is kablooey I believe). When it dies I should be able to figure it out changing tubes with known good until it works. I just gotta wait out the internittant part.

I hope. Or not?

 

[Restless Rocks]

RH 1, RH 2, and lead modes share V1 and V2. I would check for a failing LDR on the RH 1 or possibly a problem in the switching matrix. May be a job for a tech.

 

[jimmybcool]

Thanks. R1 and R2 are both a problem. R1 dies and R2 is at reduced levels. I am going to swap in some new tubes but if that doesn't cure it a tech will have next crack at it.