Jidis

Many of you guys are probably familiar with these: the fat-ass older ones where they explain not only what's there and what to check for, but why they did it.

All my good ones are for cassette and open reels I own, and I've learned a lot reading them. Did they do this with other gear from back then, or is it just the nature of the "electro-mechanical" beasts which inspired all that detail? If they did, anybody know any other good ones to seek out?

-Thanks!

PS- Recommendations of really thorough and well written service manuals from other manufacturers are also welcomed.