Sunn Beta Lead 2x12 combo volume cutting in and out.

[Bendevil]

Hey people,

I have owned a lot of Sunn amps, beta leads, model T, orig and reissue, blah blah and I love them. I have a beta lead 2x12 combo right now that is doing weird shit. I will have it on and play for about 5 minutes, and the volume goes up and down, a little at first, then gets more pronounced.
I have never had a problem with any of the SUNN gear, so I am perplexed. I think it might be the output transformer. Its happening in both channels, I have tried a billion different settings, and to no avail.
What do you guys think it is? I have all new handmade cables and all that, and I tried with a bunch of different guitars. I normally can troubleshoot a marshall or other tube stuff from going on the road, but this solid state stuff boggles my mind.

help.

[EdBass]

I'm not much of a transistor guy either, but I feel pretty confident in saying that it isn't a problem with your output transformer...
I'm sure one of the SS literate members can help with suggestions, but the fact that you thought it might be the output transformer tells me that a trip to the tech would likely be a better option than poking around in there yourself.  ; )

[loudthud]

The Effects jacks on the back of the amp pass the signal through when nothing is plugged in. These can become intermittent through lack of use. Since both channels are affected, try plugging a patch cable from the Master Accessory Out to the Master Accessory In jacks. That will bypass the switch inside the jack. If that doesn't solve the problem, try plugging a guitar or the output of an overdrive pedal into the Master Accessory In jack. If the problem persists, there is some fault in the power amp. Take the amp to a tech.

[Bendevil]

Well, I did the plug in and out of the master accessory and it is not fading anymore.

Pure Genius, you are a badass and obviously a Hero Mod.

Now will this affect channel switching?

[Isaac]

Shouldn't affect channel switching at all.