Be sure to add me to your favorites list Original YAMAHA JX30B Bass Guitar Amplifier Service Manual, Schematics Parts List Booklet. Original Yamaha service manual for the Yamaha bass guitar amp, model JX30B. It's in very good condition, with no writing, rips or tears. The tab has some bending and creasing but is intact with no tears. With Specifications, General Adjustment and Check, Block Diagram, Printed Circuit Board, Schematic Diagram, Exploded Views and Parts List. Printed in Japan, from 1980! 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! Check out my Store!