Swapping several parts from the dead SS10 into my “production” SS10 showed: the CPUs were good (*very* good), the TGX graphics card still works beautifully, and the memory modules are all still up to snuff; all individually and also all together.
Swapping the working (but limping) PSU from production into the non-working SS10 still did not bring it back to life: the keyboard beeps as expected, the fans turn, the HDD spins up, the floppy drive twitches, but after that, nothing. Nowt, nil, zip, nada, diddly-squat, zilch. At the SS10 end of the cable, the digital power-ready signal from the PSU was at 5.4V, a slight tad higher than I would ideally like – I’m pretty sure the SS10 would prefer this to be 5.0-5.1V ie: nominal-Vcc level.
Anyway, after what seemed like a lifetime laboriously retesting the voltages from the new PSU, at the SS10 end of the cable, and double-checking the wiring (pin X should go to pin Y – yes, tick!), the cabling and voltages were confirmed correct – I had not cross-wired a +12V line into a +5V line, or anything like that. No stray whiskers, crimps are OK.
Just in case, I waited a couple of hours to let the PTC (self-resetting “fuses”) on the motherboard reset, but still no joy.
At this point, the only obvious dead duck was the motherboard itself. Given that it is 23 years old (it is the original 501-1733 version of the SS10 motherboard), I foolishly convinced myself that it was just coincidence, it must have failed due to sheer old age…
Even more foolishly, I figured that the “fix” would be to swap-in the motherboard from my surviving SS10. Oops. That isn’t working either now, on either the old PSU or the new one.
Darn! Darn! Darn! So I now have two apparently dead SS10s. However, RetroChallenge 01/2015 isn’t quite over yet, I have a couple of (desparate) maneuvers to try, so… stay tuned!