Red bar across top of screen??

I had the same horizontal, solid red bar along the top of the tv screen. I have an older analog Philips Magnavox TP2785C221. It just started all of a sudden. It was on every channel. However, the bar did not appear on the other input channels (e.g., AV1, AV2). So this meant that the red bar was only occurring on the antenna input. I unplugged my cable decoder box and restarted it. The red bar went away and that seemed to solve the problem for now.