Vintage Synth Repair

>>I recently aquired a roland jx3p that operates on 230v (I'm assuming
its european) I've been running it through a stepdown transformer.  My
question is, is there anyway to permanently change the voltage so that
I can just plug it directly into a US (120v) wall plug?<<

ian- find a tech. this is one of the easiest modifications to a synth,
if it's fitted with the right kind of transformer to start with. the
transformer needs to have a split primary, which has two coils wired
in series for 220V & wired in parallel for 110V. 

even if it's a single 220V coil in there, y'r tech can look at the
secondary (output) side of the transformer with a meter while it's
running off your step-down, & then find a suitable replacement with a
110V primary. I have done this the other way around dozens of times.
it seldom costs more than $30 for the parts & the job should take
about 30 minutes at the outside.

fwiw, I've seen rolands with split primaries, single primaries,
voltage selector switches..... depends where they were made, I think,
& when. I think some of the later polys, like your jx there, were
actually made in italy.....

duncan.