Before you go any further, have you checked the -15V rail on the backplane connectors (blue wire IIRC, black wires are the ground refeernce)? Some of the older power bricks used filament lamps, which were always burning out. Start by checking the voltages on the 15 pin conenctors that the backplanes plug into. You should find a pioout in the processor printset, if not I'll try to find it. That lamp is just in parallel with the output. It'll light if the regulator is producing -15V, whether there;s a load or not, Well, First check to make sure the -15V suppply really is missing. Then check the +15V supply -- the H745 is odd in that it needs a +15V input (at a low current) as well as the 20-30V AC input from the transformer. If there's no output and the inputs are correct you need to pull the H745 and start debugging it. It is a switcher, but a relatively friendly one. When you know the fault is in that brick, I'll talk you through it. -tony