If only!  That question has been asked many times on
SGI forums like
 nekochan, for the Sony PSU (like this one) and also the Nidec.  No-one has
 ever claimed to have seen one, and the chances are Sony wouldn't ever have
 released them. 
Yea I was looking for the Nidec one for the Indigo, as mine constantly
spits out a power lost error on the console of my R4000. IIRC Nidec said
no, but Sony might be different. I think there is a private system that
Sony repair shops can access that has schematics online.
  I have thought about tracing out the relevant area of
the circuit, but it
 would take a while as the components are fairly densely packed, and I've got
 several other tasks on the agenda. 
I can imagine that would take a ton of time. And the parts list still
wouldn't be official.
--
: Ethan O'Toole