VAX 11/750 power supply fault

I've finally acquired enough of the missing boards to try for a console prompt. But I want to do this carefully. I don't want to fry any of these modules if my power supplies are not on spec. I'm still waiting for a power key that's in transit (graciously copied by another classiccmp'er), but I figured I could just set the power controller to local and crank it up. So, after cleaning and reforming the removable capacitors[1], I figured that I wanted to apply power to the system with all the loads removed, and confirm proper voltages on the outputs. I left the backplane completely empty of boards, and I disconnected the power cable to the TU58 controller, just to be safe. I get a good AC indication on the controller when I plug into the main AC supply circuit. Switching the breaker on and the control switch from OFF to LOCAL gives good air from the (loud!) blower, but... What I see on the power controller indicators is the '+2.5 FAIL' and 'REG FAIL' LEDs both light up, then several seconds elapse and the 'OVER VOLTAGE' LED will flick on and the REG FAIL flicks off for about 1/2 second, then the whole sequence repeats. Each cycle takes about 8 seconds. A couple of photos of this can be found at: http://www.rogerwilco.org/VAX11-750/psfault I admit that I've never dealt with such a complex power system before, and I've just spent the last hour or so reading through the 'VAX 11/750 H7104 Power System Technical Description' document that I found on vt100.net. Trying to get my brain around what's going on, I came across the fault isolation section and it seems that what I'm seeing on the Power Controller LEDs maybe indicates a "Fault in the CPU backplane". Of course, there is no CPU installed yet. Could this indication be normal when no boards are installed? I'm hesitant to install any of my precious boards until I'm convinced that the power supplies are good, but maybe I have to install one (or more) boards to actually close the loop on something. Further reading tells me that there is a +2.5V-at-the-backplane monitoring function in the +2.5V power supply. I haven't yet looked at this particular issue up close, but maybe the monitor circuit is not complete without the proper board in the backplane. Is this a sensible explanation? I just want to be sure that putting one or more boards into the backplane is a safe next step. Thanks! - Jared [1] System hasn't been powered since 1994. I went through the motions, but I don't think the caps needed any help; the readings during the reforming process seemed to show them in good shape from the start.