Zenith 9" Cube Composite Mod

Written by Eli Krause

This mod will disable the RF input and replace it with composite. RF could optionally be retained if desired by using a DPDT switch to toggle between A/V inputs.

1. First the original RF video source is disabled by unplugging jumper 1M. I shifted it one position over which will disable the connection.

2. Connect the new external composite signal to the CV pin. You can test with alligator clips. Connect ground to chassis ground.

3. Rather than using the existing audio circuit, I added a new audio amp with a volume knob to protrude from the back of the case. Disconnect 4P4 from the main board and connect it to the output of the audio amp. The wire with the stripe is positive and the wire that is all white is negative. Use one of the set's power rails to power the new audio board; there is a 12V source connected to pin 2 of the IF chip IC1201. Wire external audio to the audio input of the audio amp. Connect grounds to chassis ground such as the RF shielding nearby or the metal bracket holding the picture control knobs, etc.

4. I drilled holes in the metal backplate where the coax connecter was in order to mount RCA jacks for video and audio.