I have the DTA800B1 converter box and it brings the chanels in but after a period of time it displays a black box in the lower portion of the televised picture. Why is this and how do I eliminate this.
Could your closed captioning be turned on? I have 2 of these boxes, they have a dedicated "CC" button on the remote. It's in the lower right of the number pad, the "-" button. Just press it until it displays "captions Off" to turn off the closed captions.
I suspect someone was playing with your settings and turned it on, and possibly set it to a service that has no data, or the text and background color have been set to black, thus it just shows just the black box. Go into your menu and reset the closed caption options (#4) to "default".
It could be the receiver or the TV set itself generating the box. Does it do it on all channels, or just some. I have seen situations where line 21, which is where the CC data rides on the main signal be low enough or distorted to where it displays the embedded back ground (The black box itself) but the distortion of the original signal would not allow decoding of the text itself.