Prob with Triple..HELP!!

[NoGlassNoClass]

My Triple is blowing fuses while warming up on standby. Amp had been sitting on standby for about 3 minutes and popped the fuse. I replaced it and it blew again after a minute or so. Checked all tubes to see that they were tight in their sockets, replaced fuse again and fired it up. No prob during warm-up. Came off standby, all tubes look normal. Tap-test preamp tubes...no probs. Watched back of amp while playing...nothing abnormal here either.

Played amp through our regular rehearsal session...about 3 hours VERY loud. Amp sounds fine, no noise, microphony, or other tube symptoms. After playing, I let it sit on standby for about 10 minutes, no problem. Shut down amp, let it cool, and switched it back on. Sat on standby nearly an hour with no prob. WTF is going on here??? Ideas please?

 

[chedgeco]

You probably have an intermittent power tube failure. Usually a fuse blowing is a sign of that. Just because you got it to work doesn't mean that it will continue to work.

I would replace the power tubes.

chedgeco... 8)

This is from my Mark III manual, check what I have highlighted in bold:

"The big power tubes are like the strings on your guitar: they begin to wear down as soon as you play them. Severely run-down power tubes sound flat, dull and listless... just like worn strings. If you play regularly, you should plan on replacing power tubes every 8 to 12 months. Power tubes only rarely fail, but here are some of their symptoms: Loud crackling that is unaffected by front panel control settings (often you can see sparks inside the bad tube, so just replace it). Intermittent or regular blowing of fuses is usually caused by a bad power tube. And again, the problem is very often visible because the whole internal plate structure of the tube will glow red hot, the amp will distort, lose power and hum. If this happens try to spot the bad tube then turn the amp to Standby as quickly as possible. Quite often a tube will suffer a temporary "space charge short" as described; then, when switched off and on again it will work properly. This can get you through the gig but identifying and replacing the bad tube will insure reliability."

 

[NoGlassNoClass]

Problem solved. It was a bad rectifier tube.

+1 to Mesa customer service, who returned my call within 10 minutes, and stayed on the phone with me until I found the bad tube.