I have a Zenith Sentry II tv. There is black box taking up the entire screen framed by 1" worth of picture. The entire picture appears after selecting a new channel or going to the menu, but it reverts back to the black box after about 10 seconds. Picture was fine; last thing I did was to go to the menu accidentally but I didn't select any changes. Any suggestions to view entire picture? Thank you.
You must have turned on the closed caption. The black box is called the text box. On the remote may be a button labeled CC or closed caption, or perhaps it is located in the menu. I forgot on this set as it is a number of years old. Good Luck