Amazon.com: MaxLLTo 9V Power Supply Cord Charger, 6 FT Extra Long Replacement AC Adapter for Casio Keyboard CTK-500, CTK-501, CTK-510, CTK-511, CTK-515, CTK-518, CTK-519, CTK-520, CTK-520L, CTK-530 : Musical Instruments
Casiotone - Wikipedia
Casio CTK-501 keyboard /piano tested and good working condition | eBay
Casio CTK-501 keyboard /piano tested and good working condition | eBay
Amazon.com: AC Adapter for Casio CTK-500 CTK-501 CTK-540 CTK-450 Power Supply Cord Charger : Musical Instruments
Amazon.com: MyVolts 9V Power Supply Adaptor Compatible with/Replacement for Casio CTK-501 Keyboard - US Plug : Musical Instruments
CTK-501 - Past Models - Standard Keyboards - CASIO