How can I tell if my tubes died?

[captainchair]

So last night I turn on my Orange AD140 and let it heat up for a minute, I then turn it off standby to play it and I see a quick flash come from the back (it lighted up the wall behind it). The flash was light blue and now the amp won't turn on. It definitely looks like a fuse has blown but what else went with it do you think?

power tubes? something more serious? all the shops around me are out of el34s!

[Dave C]

Power tubes are a likely suspect...I'd remove the power tubes, replace the fuse, turn the amp on and see if the fuse holds. If the fuse holds replace the power tubes. If it doesn't hold it could be a preamp tube(rare) or some other internal problem. If it's not a preamp tube ...it's tech time.

There are many places on line to get tubes...TGP's own Blue Strat(KCA), Antique Electronics Supply,Tube Depot...etc I'd check screen resisters at least before installing new power tubes and rebiasing.

[captainchair]

Thank you, I ordered a bunch of different fuses (the AD140 takes 3 different kinds) in bulk so it'll be a week or so before i'll get it powered up again. I've never had tubes go out before as i've only been playing tube driven amps for 2 years now.

[bigkahuna2u]

look at the fuses you can tell if one went. If you have a radio shack around you should be able to get some fuses asap.