Here are schematic diagrams of different Commodore devices. You may also want to visit http://www.agtannenbaum.com/ (USA) or http://www.schaltungsdienst.com/ (Germany) who sell service manuals and schematic diagrams for various devices.
Mirror sites – General information – File types – Data transfer
The Commodore brandname and the chickenhead logo are property of C modore International Corp.