Be sure to add me to your favorites list Original Yamaha PSR-450 Keyboard Overall Circuit Diagram and Schematics Sheet. Great, original Yamaha set of overall circuit diagrams for the PSR-450 model of Portatone workstation keyboard. This is the large overall circuit diagram, tucked into an original Yamaha envelope with holes on one side of it for placing it into a binder if you wanted to do so. Very lightly used and in near like new condition, with some minor storage wear on the envelope. These are original documents from Yamaha, printed in Japan! This is a manual or document, this is NOT a piece of equipment or instrument. If you have any questions, I'm always happy to answer them. Thanks for looking and please check out my Store!