please, don't do this
this is a topic where i have all too much experience
unless you want to spend upwards of $1500 on a good, online dual conversion ups, you will do more damage than good. i plugged one of my older rolsnds intoa GOOD heavy duty rack mounted APC backup. the sounds from the roland power supply scared the s**t out of me.
i posted a picture of the type of surge protector you should purchase, the kind the copier people use. these are what i protect all my pronter plotters and color lasers with. ricoh WILL NOT cover one of their machines with a service plan unless it is plugged into one ofv these (ricoh could care less about your investment, but they DAMN SURE want to protect their own)
if i can do some video capture of the difference between good clean ac line voltage, ups generated ac voltage, and what the transition looks like whrn the ups "switches over" i will. then everyone will understand why this is NOT a good idea.