i use a old genesis powersupply
works great ,,,
if not most online stores have em for like 40 bux orig repalacement or for half the price you can pick one up at a radio shack
or if you reverse the poloarity - an old iomega zip drive powersupply will work fine
if you get a non original powersupply make sure the tip of the connector is negative
I couldnt use my usa adapter for my jap neo geo
because my usa neo is only 5.3 volts