Roland System 100m

I traded in for a 100M yesterday -- used -- and it's in the shop now with my Roland tech 
(he worked in Roland Japan, early 80's)  just to be checked out to make sure all OK.

The fellow I bought it from had it running on US voltage  -- but the fellow at the shop said 
he couldn't check it, as it was a Japanese model -- he needed a converter, he said.

I called the fellow I bought it from and he said not to worry -- that 10V difference 
(supposedly Japanese power is 100V, ours is 110V) wouldn't hurt.  He said it worked fine 
(and it did seem to on my cursory tour -- but this is the one that only had 2 module 
cables -- the ones in the back -- so I couldn't test it out fully.  But the fellow is local, 
knows his stuff, so I trust him).

I also called a friend of mine with a 100M -- his is a Japanese model and he runs it 
(without problems) on 110V -- he said it was OK to run a JP model on US current.

So, I won't know what the status of any of this is until next week, when my tech checks it 
out -- but should I be OK?  In general, is it OK to run Japanese models on US current?  If 
no, please make the caveats mild, as I'm already slightly stressed about this -- 

Also, if I need a converter, any one that anyone would recommend?

Best

Robert