Sound intermittently cuts out of Beta Lead head then loud hum and no input light

[begacjj]

Hello,

I recently scored a Sunn Beta Lead head and Sunn 412L cab at a pawn shop.  I finally had the house to myself so I could really crank up the Beta.  Things went great for about 1.5 hours, the amp and cab have amazing power, when all of a sudden the volume totally cuts out.  I turned the amp off/on but all I got was a loud hum and no lights on the input jacks.  Now I had several pedals plugged into the front of the amp so there is a slight possibility that the problem could be with a pedal and/or cable, although I don't think that would cause a loud hum even when the master volume was set to zero. I also have never  had any issues plugging my pedal chain into any of my other amps.

Anyways, I let the amp sit for about 30 minutes and tried it again this time with just my guitar plugged in and it worked so I tried hooking my pedals back up and the amp played fine for about another 15 minutes before the amp cut out and it started humming again.  I let the amp sit again and played just a keyboard through it for a few minutes and it worked fine but that was all the time I had.  Any ideas on what the problem may be?

[mckinnon audio]

   Hi there,sounds like some bad solder connections in the power supply to me,I
 say that because the channel led's are going out and the hum with no signal present. I could be wrong,but that's where I'd start looking.If you're not familiar with solid state amps,take it to a tech,these amps have some CMOS chips in them which can be damaged by static discharge,good luck,Mel.

[george]

I bet the +-15V "voltage regulator(s)" have issues...........

[begacjj]

Thanks guys, I don't know how to work on amps so I wll have to find somebody who can.  I have a guy who works on my old tube amps, would most tube amp guys know how to work on this solid state amp?

Thanks,

Chris

[george]

A good troubleshooter should be able to work on solid state or tube designs. This is not always the case in the market place though.