D12 Receiver question - DirecTV

This D12 receiver is used in a commercial account retirement center. Want to know if the USB connection on the rear of the D12 is an OUTPUT to a TV, or is only an INPUT from another device like a laptop, etc. Second, are the RCA outputs actually active? Problem might be a bad TV tuner when connected to the D12 coax output. Want to use secondary cables from D12 to TV to see if TV channels will work. (I can't find any info on the DirectTV web site about this particular D12 tuner.) TV is a 1080 flat panel, with multiple input options (coax, HDMI, USB, RCA). Another TV connected to the coax works, so problem is not a D12 issue.

This question, "D12 Receiver question," is about DirecTV channels, programming, equipment, and sports.