Hey UG,

Last Saturday at practice we were cranking out some tunes when my Mesa Roadster suddenly went dead. No standby, no lights, nothing. I shut it down and started checking stuff out and found the fuse was toast. This is the first I've had trouble with my amp, I've had it maybe 3-4 months? Haven't replaced the tubes yet. Anyway, I got some consult and found the problem is almost certainly one of the power tubes shorting out. I put another fuse in and it instantly blew. What I'm wondering is how I can tell which tube is shorting if any? If that's not the problem then I might have to have a pro look at it...

So yeah, basically just wondering if there's a way to figure out which tube has gone bad or if I'm better off just buying a whole new lot.

Thanks in advance for any and all input,

oooh, ive been trying to find out what the problem is with my valveking for like 5 days now, ive blown 3 fuses doing that, not good. and too make things worse, i saved up for like a year for like £150, and then gave that to my dad, and then he got the rest of my valveking as a half christmas half birthday thingy, and after just 3 days, on our first band practice with my new amp, that happened to me, and i thought it might be a tube problem.
Peavey Valveking 212

Ibanez S520EX in grey
New set of power tubes, absolutely. You shouldn't really replace individual tubes anyway, buy a matched set and see how the amp runs after that. I personally recommend JJs, the Mesa branded stuff is nothing special.

If it won't run after a change of tubes you'll have to take it to a tech though I doubt that'll be necessary; Mesas are rock-solid.
When you said you put in another fuse, what do you mean by that?
I still don't get how tubes work :S
what he means is, the fuse, in the amplifier, blew, so he took the fuse out, put a new fuse back in, then it blew again, and so that shows there is a fault in the power tubes, because they are POWER tubes, they are breaking the fuse because they are borken, to save the rest of the amp
Peavey Valveking 212

Ibanez S520EX in grey
if you look on the back of the amp, it usually has a little bit of test saying FUSE, its generally around there somewhere
Peavey Valveking 212

Ibanez S520EX in grey
The roadster has a tube rectifier setting, right? If it does, put it on the tube rectifier setting, pull the rectifier tube and the power tubes out, replace the fuse, and turn the amp on. If the fuse doesn't blow and the lights come on, just replace the power tubes and you should be fine. If the fuse still blows, take it to a tech and hope to god it's the SS rectifier and not the transformer.

Edit: DO NOT PLAY or plug anything into the amp while you're doing this. Just turn the amp on and look for the pilot light to turn on.
Last edited by Roc8995 at Apr 4, 2008,