David - I believe the ciruit board is an amp!
Behind that is a splitter for all three TVs. The white cable wire is the connection to the outide cable connector. If you replace the input that was the white wire, you will only get satellite. If you use an A-B switch, you could use all three.
Added: HWH Kick-Down Leveler; RoadMaster Anti-sway bars; Tornado Rotary Tank Rinser; Accede Backup Sensor Kit; cylinder locks (w/one combo lock); custom sink cover; Kenwood DDX 5706S front radio; Pioneer MVH-X5560BT rear radio; Oxygenics Shower head; ScanGuage II; Blue Ox Tow Bar w/RVi Brake 2; Winegard Rayzar Automatic TV antenna; Trimark Steel door lock; Dometic 310 toilet; whatever is next.