Jim, I googled it and found this website http://www.manualscenter.com/manuals/technics/sxpr250-service-manual.html#.UxLp24VLO1c that seems to have the PR250 Service Manual for $4.99

They only show the first 6 pages on the site but the list of contents say that it also has the wiring diagram.

http://www.manual-buddy.com/p/technics/sxpr250-service-manual.html also has it for the same price.