Cable TV fuzzy...trouble shooting..

That does have a splitter built into it, but what it is actually is the power supply for your rooftop antenna amplifier. Since you don't really want the 12v on the line to your TV, it also removes the 12v on the line to the tvs... It is possible that it is bad, you can get one for about $30 at just about any place that has RV parts. Also, notice the little red button on it. it is a button that turns the power on of off, and also operates the switch between the cable in or the antenna. It it is on, then it is set to the antenna, and you will get no or very little signal from the cable. Just push the button to turn it off and connect the cable, and you probably will be OK. But, there is the possibility that it is bad. Has been known to happen, but in you picture it appears to be on. if so, that is you problem. It is working just like it is supposed to.