I have an old Zenith

I have an old Zenith Digital Surround System the Receivver is a Model Z763B with a DVD Player/Recorder connected. When I play a DVD or VHS the sound can be heard through the TV and the Sound System, however, when I play a Music CD in the DVD Player/Recorder I suddenly cannot hear the music - and for years it worked fine - until the cable company connected a HD Cable box. I was wondering what wires should be connected in the back of the receiver - I think the cable company didn't reconnect all the wires. I'd like to look at the Manual to see the connection diagram.