tube help please

[astro929]

hey guys
i just picked up a mesa 50/50 power amp for my rack. i played today at my brothers house and all was good but once i got it home and hooked it all up, i was playing a bit and i noticed bright lights flashing behind the rack. it looked like when a electric line gets knocked down and it turnes into a big light show.
when i looked into the back of the rack all this light was comeing from inside one of the tubes.
my question is this. when a tube goes bad dose it just stop working or dose it do what i am describing. also when it was doing this it was making a hell of a noise threw the 4 12 cab.
this is my 1st dealing with tubes and im not sure what they do when they go.
i also noticed the tubes in the back arent the same,2 mesa and 2 electro harmonics.
i just orderd a matching quad. is ther something else i should be looking into or dose this sound like just bad tubes. any help would be great and sorry for the newby question
sean

[microdmitry]

If it's flashing, IMMEDIATELY TURN IT OFF and replace the tubes. If you blow the output transformer (which is a possibility in case of a tube short), repair will cost about as much as a used 50/50.

I would recommend that you use Mesa provided tubes with Mesa amps. Strictly speaking, that's not a requirement, but Mesas don't have bias pots, so your tubes must be pre-selected for idle current instead. That being the case, you might as well just let Mesa do it.

[astro929]

i did, i turned it off but it kinda got the best of me, after about an hour i had to go and see if it would still do it. i turned it on and it didnt do anything, it ran great,like it was suposta, i then turned it off, i didnt run it but for a min.
i pulled the tube out and it has flackes of stuff all over the glass. i wont be doing it again untill i have new tubes. if i had a power transformer go what would be the simptoms of that. when i did turn it back on, i didnt have a drop in sound or anything like that so i am hopeing that im safe, im hoping that you say if the trans was blown i wouldnt get any sound.

[microdmitry]

If you mean the output transformer, the symptoms of that would be that you'd either get no sound at all, or power would be greatly reduced.

Power transformer is unlikely to die in this case - mains fuse will blow before that happens.