Right you can not enter a digital channel, but the DVD player's output is NOT DIGITAL
Also, if the DVD plays via the sound system and the TV has LINE IN (A/V 1.2.3) you might search those while playing a DVD through the sound system.
Now.. that SHOULD work... however in my case some idiot at the factory hooked the cables up kind of like the following ASCII drawing
. Y
.W
.R
You might notice the "Y" (yellow, or video) Cable is hooked up in a different column than the White (left) and RED (Right) Audio cables..
I moved the cable (I went to school to learn how to do that.. Well.. I already knew before I got to class but I really did get certified, yup, I'm certified. take that any way you like). (Electronics).
But that's how mine works.
Back to channel entry.
The DVD outputs only base A/V. The modulator (in the switch box) Either chan 3 or 4 NTSC (Or close to it) Analog Good old fashion Chan 3 which you can manually enter.
I can also enter Digital channels manually but there is a trick.. You have to know the BROADCAST channel, not just the display channel, they may be different. For example I put in the proper channel and then the box beside the number I put in lights up with the DISPLAY channels when I'm doing digital stations. Takes a computer to keep it all straigt.