I have a box like this. Plugging in white, yellow and red wires requires setting the TV to take the video input (or one of the video inputs), as opposed to any of the channels.
On my TV there is a pop-up door by the volume, channel and power buttons and remote sensor and power indicator light. I pop this door up and there are video inputs (red, white and yellow) along with 2 buttons - "video" and "menu". On this TV of mine, I press the "video" button to cycle through 4 modes:
Antenna Video 1 Video 2 Video 3
On this particular TV that I have, the front panel video inputs are "Video 3". Since my DTV converter box is plugged into the front panel video inputs, I have to push the "video" button 3 times every time I turn the TV on.
- Don Klipstein ( snipped-for-privacy@misty.com)