Now that my Prime 2455 is fully operational again, I want to thank everyone who offered advice here. After giving up on repairing the power supply, I decided to buy one. Had I known they'd only cost $100, I'd have bought one sooner. Well, that was my Christmas present to myself for Christmas 2000. It arrives, I install it, press the power button, and see a message from the VCP about it beginning its self-test. Then it completes, and then I get the date & time, and then... Then I get the "ON" LED flashing defiantly at a 2 Hz rate. Time passed, and I began to suspect that more than the PSU had gotten toasted. I intended to start saving money to shotgun the machine, board by board, until I had it running again. More time passed and no savings took place. Well, in steps a lister who I believe wishes to remain anonymous. Said lister faciliated the acquisition of said boards, NONE OF WHICH SOLVED THE PROBLEM! Not his fault, of course... and there is more of this part of the story I'll relate below, that should be of interest to all ClassicCmp listers. But I should thank the lister again, he knows who he is, and without his help, the Prime would still be an emotional singularity... Finally, again in desparation, I posted again to comp.sys.prime. This time, an owner of the same model I have, replies. Over the course of several dozen e-mails, we narrowed down the problem. As it turns out, the replacement PSU was either failing to ground or was in fact asserting a line known as BBUREQ+, which signals a battery backup problem to the virtual control panel. Grounding that pin got the system past the point in the boot where it would flash the LED. I suspect a forgotten FCO... More problems... it says it thinks its a 2450 and it can see it has 2455 parts, not right, won't boot. Swap VCP. Same. Swap in my original VCP. Ok, now it's happyy... nope, now the CPU won't verify. Swap in a second CPU board set. Nope. Ok, go for broke, swap in the remaining CPU board set, replace newly-provided CPU board interconnects (top hats) with my old ones. Replace my VCP-to-CPU cable with 3rd party cable. Now it's verifying the CPU ok, but can't autoboot from drive unit 0. I freak thinking it's the controller. Better that than the drive, tho... The bulkhead cable had gotten munged a bit, so I began to suspect it, and mangle it further trying to fix it. Still no good. Ok, stick a new connector on the cable. Nope. Remove and reseat the external cable to the duplex shoebox. Nope. Try different SCSI unit addresses... hey, that worked... But I can only see one drive. I mess around with various adresses, suspecting a dropped bit in the bad cable. Still can't get them both online. I finally ended up swapping the two unit select switches, or rather, the connectors, so that each drive was using the other's selectors. Then set them for the appropriate values. Bingo! Autoboot to unit 0 and unit 1 is also seen and mounted. So, I'm able to boot it into: Primos Rev. 23.4.Y2K.R1 Primos Rev. 20.0.8 Primos II Rev. 20 and these from either disk or tape. Whew! ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Now, on to the part of the story that's widely applicable. Don't underestimate the potential usefulness of a 3rd-party service organization. The company in question services other stuff that they actually make money from. But they make no money from servicing Primes. They have a policy about repairs, as since these days, it's mostly remove & replace. Techs with experience are expensive so customers tend to do their own work. But this firm charges for a part IF and ONLY IF it effects a repair. Now, that's probably standard. But when a part doesn't fix the problem, this firm has no desire to incur the shipping costs of returning the part to them, and they sure as hell can't get the customer to pay for it if it doesn't contribute to the fix. So the upshot of this is that I got to keep all the spares, and the lister who facilitated this will be charged only for the time spent talking to a technician (who found the thing about the LED flash and what it meant *ABOUT 4 HOURS* after I got the system semi-operational as described above). equipped (not much just a little) to financially faciliate a repair operation like this one became. But I suspect that like me, a 3rd-party servce organzation would be about the last thing you'd consider, as a hobbyist. You'd assume like I did that it would cost a fortune. But the technician I spoke to was also a preservationist (although now I forget what he likes!). So before you give up on that old iron and dump it, try calling for service, and when you get the technician, explain to *him* that you're non-commercial and can't afford much. You may just land a bargain. Regards, -doug q