We have over the air T.V. On digital channel 9.1 the picture is flickering and there are thin black lines every inch or so across the screen. Our 2 other digital T.V.'s are fine and the antenna connection seems fine. There is nothing else near the T.V. that could be causing interference and it has been in this location for over a year.

SOURCE: screen blacks out on HD channels

Saying that the problem is with your TV doesn't make any sense since your TV is fed from the cable box.  Your TV doesn't know one channel from the next.  If it had a problem it would effect all channels.  You may not have enough signal to the INPUT of your cable box due to a problem on the pole or at your house or both.  Insufficient signal can cause some digital channels to not get decoded properly by the cable box.  The lower channels will show noise symptoms such as what you describe but they won't crap out altogether like the digital ones.  Have a cable tech come out and measure the signals.

Do you have splitters in line with the cable anywhere?  If there's any way to beef up the amount of signal getting to the cable box try it. 

SOURCE: line across screen

I have the same problem with my 42 in. The line started to show up randomly about 1 month after i got my tv. The line isn't a line of dead pixels since when i change the aspect ratio or the tv the line moves up or down. I called sharp about the problem and they said it had something to do with my computer but i don't think that can explain why the problem shows up on all my tv inputs.

SOURCE: Sharp Aquos LC-32D41U

The unit has bad drive ic's,which is part of the lcd panel.It is not cheap to fix.

SOURCE: Thin line across the screen

I'm guessing that this is a CRT based TV, not an LCD. That being said, the problem is a failure of the vertical circuit. Usually this is a small flat IC (LA7837 or similar). Try resoldering the pins if you can first. If that fails to resolve the problem, replace the IC. Please be aware that there are potentially dangerous high voltages present even when unplugged.

Keep us posted.
Dan

SOURCE: I have a Westinghouse 26 inch TV.

I carried my Westinghouse TV to the basement. Unplugged the antenna from the digital converter box and connected it to my digital TV. I then re-scanned for channels and found channel 9. After carrying the Westinghouse TV back upstairs, I connected the original set-up and tuned to channel 9 which was now showing on the screen as no signal. From that point I moved my VHF dipoles until I had located the correct position for reception. A little labor intensive, but I was fortunate to have another antenna that was receiving channel 9.