What would cause this head to keep tripping a circuit in my condo? I tried several different outlets, same result. I'm using a Neutrik cable into an LDS 8 ohm cab. When I hit the power switch, it hits like a halfway position then all the way up and the circuit trips. I took the top lid off to see if there was anything obvious. There's a black metal plate, probably 4" square, in the front right. I noticed the large bolt on top was loose so I hand tightened it down and tried again. The fans start whirring for a second and then it tripped the circuit again. I've got the front panel switch in mute position. Help.