A buddy of mine has an old JBL PD-12(Forgot the name, but I think this is it). Anyway, he had a power surge a while back and is just now trying to fix everything. With no signal hooked up, and the sub just plugged in, the driver goes crazy. From what I heard, it sounded like power was intermittently coming on and off. The sub went through major excursion with each burst. I inspected the amp for shorts, bad wires, anything, and I must say that, aside from the gallon of silicon on all the connections, everything is in order. So, my assumption is that the power supply is the culprit. That is the only thing I didn't actually check. I figured if I was going to bust out a meter and give everything a really good check-up, it would have to be some other time because there was walleye and crappie waiting for me in the kitchen. Anybody have any ideas? I just told him to order a PB10-ISD because he's had the JBL since '97 or '98. He's thinking it over.