Loud "pop" when turned on

[mesabplayer]

Hey there..Great site, I just stumbled on it..I have a DualRec , 2 channel, from '96. I've never had a problem, but now, it pops when turned on. Makes a steady hum, and it's like a "half-sound", very scratchy, just not right..

Any ideas? It's got Groove Tubes, w/ very low hours.I haven't played it in a while. Been playing through my Digitech, just not the same...I'd appreciate any info., or thoughts..

Oh, by the way, it's a fantastic amp!!!

Thanks
Jim