Large black box keeps covering 80% of the screen

I have a similar problem using an older 20" flat screen standard definition TV. (not High Def). I can see a little of the picture but more than 2/3 is covered by the black. My model is LC-20SH7U.
I used sharpusa.com "contact us" section.
Hopefully I get some kind of reply to report what they say.

That sounds like a text box. Press the cc button and keep pressing it. You will see different closed captions options on your screen each time you press the button. Finally when it says cc off stop pressing the button and you should no longer get the black box. If you have a cable box connected you may also have to disable the captioning on it.

a black box is covering my tv screen except for around the edges. I can use the dvd player, but i cannot watch cable. it is as though there is a security feature to block tv, but i cannot get it to go away!

This is a background for text, even though you aren't seeing any text at the time. Since it covers most of the screen, it sounds more like a demo mode screen than closed captioning. Go into your setup menu and make sure that neither of those is selected. If necessary, restore the factory settings. I'm assuming that this is coming from the tv itself, and that you don't have a VCR, Tivo, etc. Good luck!

Okey dokey... you'll need to remove the back cover on this set and make an adjustment to a part called the "DMD board". The DMD board is a large, flat, vertically oriented board with a perforated thin steel cover over it.

Basically, there is a tiny tiny 'tv screen' on the front side of this board and by moving this board around you can 'fine tune' the picture position. All that is typically required is to loosen the screws around the perimiter of the board (JUST SLIGHTLY! You don't want the board to fall out of position!) and slide the board around, preferably with someone watching the screen, until the picture looks perfectly centered.

Something to keep in mind is that the TV will not operate with the back off due to their being a small switch with a blue lever on it whose purpose is to prevent the TV from powering with the lamp cover off. Just tape this switch up so your set will power and then you can rock and roll. Good luck!

Note that the large black box goes away when pushing buttons on the tv (ex: the black box will disappear to show the volume setting when changing the volume on the tv but it will cover the picture and the menu display of the dtv box).

This is caused by the closed caption setting of the television set NOT the captioning of the converter box. To fix this you must open your television's menu, find the ccd/closed caption option, and turn it off. This is a frustrating problem as when most people are told to shut off the captioning they try to do so at the box.

Normal dtv box captioning will appear as a small text box at the bottom of the screen as you would expect - not as a giant black rectangle that covers most of the screen. If you do want to shut this off too you will find that you can't do it through the usual menu options (the menu will only allow changes to font, color etc.) - there should be a ccd button on the remote that when pushed will scroll through ccd-1, ccd-2,... off.

It sounds like a text box that isn't receiving any text. If it covers almost the entire screen, then you might have accidentally got the settings into DEMO mode. It could also be a box for closed captioning, but that usually covers just the lower part of the screen. Either way, the solution is to go into the setup menu and restore facotry presets.

Try turning off the text box function of the closed caption decoder.

I work at at a school, and we had the same problem. Turns out, it a Closed Captioning problem.

We found the manual, and it states that "If a large black box covers 80% of your screen, the Text mode is probably set. Press 'Closed Caption' to turn it off." The "Closed Caption" button is on the remote. If you don't have the remote (as in our case), you can go to "Closed Caption" in the menu, and pick something like C4 and T4. That stopped the black box for us.

have your tv checked by a tech.probably your chip the eprom needs to be reset by lifting it up from the board and resolder back.some one could have put in a code for those channel.good luck.