if your looking for one compleate and not just the screen, there is a special AC adapter the comes with the screen. the manual said that you cant use the orginal adapter because it may cause a fire, and you must use the new adapter. ive used both, the orginal didnt do anything....
when i find it ill post the amps and model number of it, seeing as those bits of info are the only thing to tell it from a normal PSone adapter...
I love the screen, i have found it very usefull (not just for PSone games). I was lucky to get it for $15, it was on clearance and the toys r us was closing down...