I do not have any experience with VAX 11/750's, but I have once heard the following about the PSU. They are not like the PDP-11 PSU blocks. Those can operate without any load as they are series regulators. The PSU's of the VAX 11/750 *must* have a certain minimum load for correct operation because they are switched-mode. I do not remember if those SMPSU's can be damaged by running them without a minimum load, but I know SMPSU's that will die without a load. So, to be on the safe side: get some bulbs from your car, connect them to the outputs of the PSU to shine a some light on the restoration of the VAX 11/750 ;-) success, - Henk.