If anyone needs schematic diagrams for any pro audio gear like what musicians use, such as guitar amps, power amplifiers, vintage tube amps, musical gear like keyboards, effects pedals, guitar wiring diagrams and service manuals, check out
https://schematics.ca . I'm a road musician and an electronics tech and I got schematics for just about every piece of gear in the band from this site and they are free to download. It's always good to be prepared in case you fry something while on tour.
https://schematics-free.com has a lot of free audio schematics as well. Hope this helps!