I own this receiver. It still works. I have the original owner's manual, and it has a schematic in the back of the manual. If you need a copy of it, let me know. It would be hard to scan, but I can try to get a good image.
I've got this amp as well, and am trying to figure out a power problem. Fairly sure I'll need to replace the Tx, but will need the schematic to figure it out. Any chance you could scan and email it to me? its [email protected]