Yamaha's old service documents are among the beautifullest technical prints ever. The schematics, the graphics, the typesetting, the yellowed paper, the fold-outs, the cover, the odd metal binding... just wonderful.
I have the original CS-50 service manual, and it's easily the classiest book in my library. :-)
/mr
PS: The CS-40M document seems missing on http://therogoffs.com/cs80/
Thanks for keeping up the documentation work though!