Tube amp problem!

[amra]

All of a sudden my amp (a Red Bear MK120) started flaking out on me. It is an all tube amp, made in russia, imported by gibson in the 90's. Soundwise it is somewhere between a JCM800, and some say a soldano. A really nice, unique sounding amp.

Anyway, I suspect the tubes need to be changed, since I haven't changed them since I got it. What it is doing, is the sound is cutting on and off in a tremolo pedal like effect. When I turn the power off, as the amp is shutting down, it stops doing it and the sound fades out like normal. Sound like tubes? or should I take it to an amp tech?

Thanks!

P.S. Here is a link to a guy that uses one, if anyone is curious.
http://www.gibson.com/whatsnew/pressrelease/2002/jul24a.html

And more info here:
http://www.ringomedia.net/spetel.html

 

[ggunn]

All of a sudden my amp (a Red Bear MK120) started flaking out on me. It is an all tube amp, made in russia, imported by gibson in the 90's. Soundwise it is somewhere between a JCM800, and some say a soldano. A really nice, unique sounding amp.

Anyway, I suspect the tubes need to be changed, since I haven't changed them since I got it. What it is doing, is the sound is cutting on and off in a tremolo pedal like effect. When I turn the power off, as the amp is shutting down, it stops doing it and the sound fades out like normal. Sound like tubes? or should I take it to an amp tech?

Thanks!

I'd take it to a tech. This sounds like it could be an arcing filter cap or power tube. Either way, it could be very bad for your power transformer to run it this way even for a little while; I wouldn't turn it on again until it's on a tech's bench.

 

[cusebassman]

Yea, time for a tuneup. Even if it is just the tubes, you'll want them replaced and have the power tubes biased by a professional... I usually tinker with that sort of thing, and even I won't replace em myself.

 

[amra]

Damn.Thats what I was afraid of....
Thanks for replys, I appreciate the info.

To the amp tech it is...

 

[ggunn]

Damn.Thats what I was afraid of....
Thanks for replys, I appreciate the info.

To the amp tech it is...

Well, ya' know, that's why those guys have jobs. I'd much rather spend my time playing, and I don't mind paying for a job well done.

 

[JB1979]

One of my amps had similar symtoms, it turned out that the fx loop jack was dirty from lack of use.

 

[ocnor]

One of my amps had similar symtoms, it turned out that the fx loop jack was dirty from lack of use.

Same here. I had a Marshall that would fade in and out. If I ran a patch cable from the FX send to the FX return it worked fine.

 

[Pier Calacino]

It sounds to me like an electrolytic cap in the power supply but I would take the advice of others and see a tech.

Pier