If I had to rely on computers and the internet to supply schematic diagrams for vintage electronics , I'd be done before I got started.
You can't beat a set of Ryders manuals or Howard W. Sams folders.
Books that were authored about a subject, when that subject was new at the time, are frequently the only records you can go to and get the facts.
Book in hand is the best !
Belfer Audio Archive
222 Waverly Ave .
Syracuse N.Y. 13244-2010