007 has provided good information. However, he was speaking in code. I thought a brief explanation would help.
By "tone out" he is talking about a device (which can be divided into two pieces) that can be used to verify the continuity of cables in the coach. One piece is made of a coax slip-on connector, battery, switch, and sound module. The second piece has a coax slip-on connector and wired to complete the circuit. There's a You Tube video to explain the process. The URL is as follows -
-
Once you figure out which cable goes where (from the TV side to the junction box, etc.) you'll be on your way to solving your problem.
It looks like a previous owner took out the video selector (TV1, Player, TV2) since he/she felt it was no longer useful. That box supports selecting which unit gets what signal (Tape, Aux, Cable, Antenna). More recently this box has been replaced by a head that supports HDMI connectivity.
The cabinet over the driver area is where all the cables terminate. At the termination is where the video selector went. The cabinet on the passenger side (notice the venting at the top of the cabinet) where Newmar planned for a satellite receiver to go.
All-in-all, getting the spider web of cables straight is the first task. The second is finding where the cable/antenna booster switch is located. Generally, Newmar installed it on the passenger side (to the right of the TV) however your coach may be different.