My Marshall has been silenced

ActionArnie

So I was playing at a thing last night and as we were about to start the first song I heard a bit of a crackle from the amp which I thought was maybe my guitar jack playing up. Fiddled with the jack a bit and it made no more noise so I thought it was fine ... quick light strum and there was no sound .... nothing at all.

Frantically debugged switching out cables and such and the issue turned out to be the amp. Switched to one of them Marshall AVT types worked fine (except for the fact that it sounded absolutely rubbish with no time to EQ and all the rest of my gear set for the JCM600). At this point the amp had been on and been running fine through our warmup for about an hour so everything should've been hot and ready to rock.

So later on when time to pack up I tried the JCM600 again. Still no sound. Valves are all lit and the switch light and channel select light are on. I tried the external cab jack, no output. I tried the DI at the back, no output (I've never plugged anything into the DI before so I have no idea if its ever worked).

Anyone got any ideas?

Manfred-Klose

i own a jcm600 as well.

mine also broke down while i was playing a gig.
it turned out to be some black caps on board close to the transformer.

but its a hassle trying to fix that amp.

plug your guitar into the fx return , if there is sound it means there is a problem in the pre amp.
check out that input jack first.

you have to take it to an amp tech.

bottledtone

I've done a repair on a jtm600 which is the same amp, the name was just changed to jcm600.
Hell of a job to work on that thing. Three different pcb and the valves are right under the pcb so it cooks them nicely!
That amp needs...needs a fan to keep components cool. If it crackled, sounds like a dry joint. I think you should look at the board that's above the el34's
Good luck

ActionArnie

Thanks guys, next question ... anyone know of valve amp techs in Durban?

Kalcium

Apparently Dennis from GVM is an amp tech

ActionArnie

Kalcium wrote: Apparently Dennis from GVM is an amp tech

Shot thanks, will give them a call