Assuming you have Satellite TV and not Optik. Depending on your equipment you may have a powered signal switch that needs to be reset. If the signal on this switch is stuck it explains why only one receiver is getting signal but the other 2 arent. With your satellite remote, hit Menu > 6 > 1 > 1. Thats Menu > System Setup > Installation > Point Dish. Now click on Check Switch. If the switch type is listed as SW44 or DPP 44 you have a powered switch somewhere in the house. It's most likely at the main electrical panel if the coax cables from the dish enter the home at that point, or it might be behind oneo of the TVs if the cables enter the home in one of those locations. Look for the silver metal box with all the cables running through it. One of them has a smaller silver box with a black power cord plugged int. Make sure that power plug is properly connected. If it is, unplug then plug it back in. Try rebooting your receivers after this (Hold power button down for 5 seconds).
@Chicnstu All my receivers are coaxed directly to the dish no silver boxes. The receivers feed voltage to dish and return the signal. I go to menu --- system setup----installation -----point dish---there you will see signal strength----there you can check switch or the help menu.