Mesa Boogie Roadster issue

[gotGASbad]

Had problems with my Roadster head at a gig this weekend just gone. . . when switching between channels, the volume would drop out completely, then slowly surge back in after about 5-8 seconds (mid-song, mind you!). It was a very hot venue, so I turned amp off completely during each break. It would work fine for first 20 mins of each set, then problem would start again.

Has anyone else experienced this before? I have another 2 gigs this coming weekend, so I need to get to the bottom of it. . . . . HELP!

[mbrown3]

Hmm, it sounds like you might have a "notanegnater" issue. My suggestion...get an egnater mod50. :D

Seriously, though, that's weird. It sounds like a power/transformer issue to me, but I'm far from an expert. Hopefully someone here will have a better idea...

[John Price]

I don't have the same amp but I did experience a similar problem.
How old are your tubes? I've had this problem with 2 different situations. One was with a bad power tube fading in and out with the volume. Replaced it (them as a pair) and everything was fine. The other issue was with my effects loop. Believe it or not the loop jacks needed to be cleaned so I used some deoxit on the end of a spare cable, insert and twist and I was back up working fine..
The amp was a Mesa LoneStar. I still have this amp and gig weekly with it trying to keep it clean...

Good luck!
If I can think of something else I will post it for you.
JP

[Tremendo]

Yeah, I would think power tubes. Also the easiest to check/replace. I had a slight drop then build up with my Mark III and the problem was the power tubes.

[kurt1981]

Hey, I know the relay switching system in these amps is crazy, so maybe there's a problem there. I had the similar fx loop problem mentioned earlier, and some contact cleaner fixed it, or you could just insert a short cable in the loop, and leave it there, like a jumper. If you can, try and turn the loop function off, I assume the roadster has this feature, and take the master section out of the circuit. See if that helps. I remember reading something about those amps having a few slight switching bugs, but I thought they were limited to early production runs.

[Mister T]

that sounds like a power tube issue to me.

[gotGASbad]

Thanks to everyone who has suggested something. They're all valid issues. Only problem is that I can't get the damn problem to replicate, so I can't try and troubleshoot it if it's not happening.

I was in extreme 40C+ heat, so when the tubes heated up the combined temp might've tripped something that's on it's way out anyway, but until I can replicate it, I'm sorta reduced to dragging a spare with me everywhere.:(

Bit annoying as this Roadster has been faultless until now with over a years' worth of solid use.