Figured out why my JCM2000 DSL50's volume cuts out after a few minutes after turning on but what is the fix?

[Marshall Stack]

This issue has driven me crazy trying to figure out for a few years now why my amp cuts out for a few minutes and then eventually comes back. I have tried everything but it just happens that I recently left the rear grill off the amp after checking the bias that I noticed the preamp tube on the left (V1?) wasn't glowing so I just pressed it down a bit and then it glowed and the sound came on. I have done this several times and it has been working. I have replaced the tubes before while having the same problem so would it be the socket itself or cold soldering for that socket?

I could take it to a tech as it is a 2001 and it probably needs the original capacitors replaced anyway, but would like to see if someone here has an opinion or experience.

 

[anitoli]

Either the tube socket's connection to the heater pin is wonky or the solder connection to the heater pin is fractured. That's what i would look at first.

 

[Jon Snell]

Or it wasn't seated properly (fell loose in the socket) and pushing it back in has fixed it.

 

[nortiks]

If it isn't something as simple as just needing to clean the tube pins and socket, I'd next re-flow the solder that connects the socket to the board.

The (very) good news is that this can be done without disassembly other than pull the chassis out and remove the tube. All of the socket to board solder connections are accessible via the tube hole in the chassis.

Mine had pretty much the same problem you describe and a look thru magnification showed what appeared to maybe be a crack in the solder so I re-flowed it and the problem has never come back. And of course I did that after trying to clean and the problem not going away.

 

[seansnuhouse]

The jcm 2000 100 watt versions have dc heater voltage on the first 2 pre amp tubes so your 50 watt may have dc heater voltage on it as well but if tube 2 is working then it's more than likely a solder joint or connection to that solder joint