Hmm, yes I don't recall if the stock PSU was
guaranteed to work on 110V
automagically, and so the US models got exactly the same ones as the UK.
I seem to remember an obvious 'fit for 115V' link on the Beeb PSU board
which did the stnadard trick of convertign the mains input stage from a
bridge rectifeir to a voltage doubler. I asusme that was fitted inthe US
Beebs.
-tony