My 1990 Hunter Legend 35.5 (new boat to me a month ago) has developed a rather serious electrical problem. It started yesterday with my electronics flickering on and off (depth sounder, GPS, knotmeter). I went below and the voltmeter on my main panel was bouncing all over the place. Back at the dock, now when I switch on the DC Main I get no reading at all and none of the DC side of the panel works. With the engine on, I get a little flicker of the red light when I switch on the DC Main. The AC side works, all three batteries read 13.2 volts. I can't seem to find an electrical diagram of the boat to help me out. There is power to the little black box behind the main panel although only reads 10 volts and seems to be continuity between the battery switch and that box (not sure what that box does has 2 large red and 2 large black cables on the top terminals and 3 small cables off the bottom and seems to supply the DC side of the panel) Any suggestions as to where to start looking? Thanks