I get a black square on my screen after about 30 seconds when I tune to some channels. Does not do it on every channel. If I tune to another and then back it will be gone but soon reappears. jd

This sounds like your closed caption has been activated. There are several closed caption options that aren't used for anything, and if you select one by pressing the cc button on your remote by mistake, it will cause the problem you're having. To fix the issue, locate the cc, ccd, or closed caption button on your remote. Press it until you the option "off" appear on the screen. Once you see "off," simply stop pressing the button and the word "off" will disappear.

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When i turn on , only has sound, no pictureat all. after about 5 minutes pictures come on , it will stay on for about 5 -10 minutes then the tube go back to black again just sound only, it wait for about 5 minutes for no picture and then the picitures come back on again. please let me know what's wrong?
thank you