Does anybody know anything about solid state amps? I have a vintage H&H 100 watt combo, like Daniel Sash used with Bauhaus and Marc Bolan used, in a head version, I think, with T. Rex. It sat in my basement unplayed for a few years and now, when I turn it on, I get no guitar sound, just a loud hum, sort of like a feedback sound, but at a load steady volume, like holding a microphone steady in front of a PA speaker. This happens when I unplug the speakers from the head and plug it into other speakers, as well. Any ideas on what might cause that or I can do to fix it? I am fine with guitar wiring, but not really an amp guy.