Call a Music Store and TELL Them The MODEL Of YOUR Unit. ASK Them For The POWER SUPPLY New Or Used and How Much, usually they have many laying around..
My PSR 2100 Yamaha takes a PA-300. Here are specs.
PA-300 Power Supply, 16Volt 2.4 Amp. The Positive (+) is in the "center" part of the plug on mine.
caryb1999@yahoo.com