oh, this looks very interesting - if I cannot find a complete spare part I would be interested in a PCB and the part number for the 19-pin connector to the backplane.
Your schematics with the wiring of the power connector is also very helpful for me.
However, the TDK PSU is a bit costly - it costs me more than the whole HP 9000 system with color monitor and hard disk, so I would try to find something cheaper (maybe a standard PC PSU with sufficient power).
I think I do not fully understand the operation of the "power good" signal - is it just raised to 5V after a certain time when the PSU has started up properly? Or is there more behind this signal?
Sorry I am an aerospace engineer and electronics is only a hobby.