RiscPC 610 PSU - 110 VAC?

[Tony Duell]

> 
> Howdy, folks.
> 
> I just acquired an Acorn Risc PC 610 from a chap in the UK. The PSU  
> in it is labelled as a 220V-only affair. I understand there was an  
> autoranging PSU revision, but this does not appear to be one of them.
> 
> Does anybody have information on modifying this unit to work with  
> 110V mains? Or a lead on a replacement PSU that has a switchable or  
> autoranging input voltage?

Nothing specific (my RiscPC information covers the motehroard and CPU 
board only, not the PSU, which I'll bet was not designed by Acorn). My 
_guess_ (and it is a guess) is that the PSU starts by retifying the mains 
to give about 350V DC. If you converted that stage to a voltage doubler, 
and left everything after it the same, it might well work. Of course you 
need to check if there's anything (fan?, but I doubt it, startup 
transformer) that runs directly off the AC mains and modify that too.

Only attempt this sort of thing if you have expeirence in working with 
mains voltages, of course.

-tony