The massive 1975 Zenith combo has arrived...

[DaveWM]

if its like other zenith combos the TV does NOT use the tuner amp, but rather has a cut out switch the disconnects the speakers from the amp and switches to the TV based audio (and may or may not kill power the the stereo tuner/amp). On mine I made up a a new wire harness that bypassed that and just drove a small interanl speaker (there was a place for on) from the TV audio and left the main spearker connected to the amp. this way I could power up the amp and drive the L and R directly from my video source. it REALLY makes for a nice setup with that powerfull amp in true TV stereo sound. I would just use the tape inputs. I left the small speaker hooked up so you would just leave the TV volume turned down. I did not want to have the audio stage unloaded. The entire process was just done by the new wire harness, I even left the old one in place so it would be easy to return to the orig setup, if for some reason that would ever by desired.