MC240 HELP PLEASE

If the tubes light up, it isn't the thermistor. Everything will be off if the thermistor is dead.

There are many capacitors in there and I bet many people wouldn't replace all of them like I did. Look at the caps and see if they look like originals. It should be pretty clear. There will be two tall silver ones on the left of the choke inductor (looks like a mini power transformer, half the size of your fist). If they are labeled by engraved print, they are probably original - new ones have sticker labels in general. Then look at the two caps on the right of the choke. If they have paper outer coverings, they too are original. New ones have plastic wrap. If any of these 4 caps have a problem, your amp is in trouble and will need a specialist to assess the damage.

If all these caps seem ok, replace the fuse. Sometimes they can look fine but not be. If you replace the fuse and nothing happens, you need to have your amp checked out.

Good luck and keep us posted.

Arthur

That's right - now that you mention it, there is a fuse in there. I think it is for the bias stage in case a tube goes bad.

If a fuse blows, it is because there is a problem. You will have to find the problem before you're back to normal. It sounds like you have a tube that has gone bad. But which one? That is a tough one without a tube tester... Look at each tube very carefully and see if you see anything strange. I have seen some develop black spots and/or sometimes you will see a whitish film where the vacuum was lost (near the base typically).

Arthur