On 01/22/2018 08:07 AM, Adrian Graham via cctalk wrote:
   At this stage
I've got no idea if it's a SMPSU or a linear (I've not 
 popped the panel
off)... I suppose if it's linear then it perhaps doesn't
 even need a load to do its thing. If it's a switcher then I expect it'll at
 least need something on +5V, and maybe +12V too (unless it has built-in
 load resistors to keep the regulation happy, as designs occasionally do).
 It's actually 3 separate boards and 2 identical discrete PSUs for +12 and
 +5 in a massive metal box, the thing is a beast and fits along the whole
 side of the machine behind the Q22 backplane. 
 
Aha, so it is... I just removed it for a visual inspection. Pretty clean
inside, some dust, five or six mouse turds (but no sign of piss damage), a
chunk of slate, and a golf tee.
When the bit of slate fell out I was a little concerned that it was a
fragment of ceramic IC/component packaging, but I really do think it's just
a piece of slate tile or whatnot that had somehow found its way in there
over the years.
No obviously-roached caps or other components, so I'll figure out some form
of loading and give it a go.
cheers
J.