Get a DMM on your power supply and check the voltages.

Those measurements do not look suspicious. Check the parallel port cable from the transformer

sounds more like a PC issue then a power issue.
If I was you I'd just take the PC out and reseat everything, the prism, ram, reseat connections etc...
can't remember is there more then one ram slot in that motherboard?, maybe put it in the second slot if it has one.

Yes I agree. I was looking at those fuses thinking the power was lost with all those solenoid voltage LEDs off, but LED9 is on so the 50VDC is getting to the driver board. The solenoid voltage is switched on later during boot up via a relay for all those other lines out So as you suggested, reseating everything, especially the finicky Prism card is a start,

Is the fan running on top of the CPU? No bulging capacitors on the motherboard?

There is more than one ram slot on my motherboard, although I understand there was more than one version used. I once added ram to see if it would improve anything, but all it did was make the already long self test even longer.

if you did it once I doubt a second time is going to help much.
I know almost every time I have issues with a new PC build and it won't boot, it's almost always a ram issue.

yeah like wayout440 mentioned you could check for bulging caps on the motherboard. There are a few on there that will cause the issues your talking about.
You could even just replace them all, think it took me about 30 minutes... there were tons of caps on that mobo and I didn't have a de-soldering iron at the time.

I finally just bought another pc and went with pinbox, the problem with those old P2K parts is once they crap out your kind of screwed.

It's also possible that your interlock and/or memory protect switches died, which would help to explain the lack of voltages on the Power driver board, and the failure to continue booting. I've had this happen on a few WPC games, replaced them both and was back in business.

If the problem hasn't been specifically isolated to the motherboard by swapping the Prism or motherboard, then the Prism card could be suspect. While reseating the Prism card often solves issues with communication between the motherboard and the Prism, there's a lot of things that can become a problem on the Prism itself. The Prism sandwich has socketed ROMS that could have chip creep, for example. Mine had broken traces at the connector that had to be jumpered. It's a delicate thing, so be very careful if you need to pry the two halves apart to investigate it.

congrats , glad you got it working again.