Amp problems, advice needed!

[Brow]

Hey guys.

I was at band practise earlier and while I was playing, my Marshall JTM60 combo just cut out. The mains power was still there, it just lost all sound.

I looked around the back and 1 of what I believe to be the power valves was glowing immensely (more than the other power valves) and was extremely hot. So I turned the amp off, unplugged it and left it alone.

I've noticed over the last week or so that my 60w valve combo has had trouble keeping up with the other guys Peavey Bandit or 40w Marshall valvestate combos, so I figured it was maybe ready for a new set of valves.

Does this sound like a symptom of being a valve problem? If not, what could it be and what should I do about the amp?

Thanx for any info.

Craig

[TwilightOdyssey]

Sounds like a blown power  tube, B+ fuse, or both.

[HJM]

Try new valves, but with caution, could be lots of things. I prefer brining an amp up with a variac after this sort of problem. Then you can monitor all the voltages. Marshall bias supplies can cause this problem too.

[Brow]

Thanx for the posts guys :)

I'll just find a local competent tech and let him sort it out I think :)

Craig

[chrisola]

buy my JCM800, it has some spare power tubes :P :P

[Ratrod]

It's probably the tubes. When you've changed the tubes and rebiased the amp, keep an eye on the tubes. If the same problem occurs it's your output transformer.

[Brow]

Thanx for the posts guys :)

I'm going to buya  pair of power valves myself (so i know how much they cost) and just get a tech to fit them and look the amp over to make sure everything else is ok.

If that fails, I'll just have to make due until I cana fford another amp to replace it.

buy my JCM800, it has some spare power tubes :P :P

I already have 1, but the spare power valves would be handy  :D