I have tested the keyboard with both a power adaptor and batteries and both work great. "A revolutionary portable keyboard featuring a built-in printer.
Vintage 1982 Yamaha PORTASOUND MP-1 Electronic Portable Keyboard - FULLY WORKING
Yamaha PortaSound PCS-30 Vintage Keyboard Made In Japan + 6 x Yamaha Playcards
Yamaha PortaSound PCS-30 Vintage Keyboard Made In Japan + 10x Yamaha Playcards
Yamaha Portasound MK-100 Vintage 1983 49-Key Synthesizer Keyboard
YAMAHA PORTASOUND PSS-270 Electronic Keyboard vintage 1980's
Vintage Yamaha Portasound PSS-31 Electronic Keyboard Synthesizer Tested Working
