Unstable signal Picked it up at a garage sale. Picture was beautiful. Brought it home, plugged it into our cable and it says unstable signal. What the heck did we do to it?

Hi,
Are you sure it says unusable signal instead of unstable signal.
This means that you have the wrong input in place in the tv. If you got the original remote with it there may be an input button. on it. Some RCA's use 00 for the video input. If your cable goes directly to the antenna connector on the back you should get all channels when you do auto search in the menu provided you have the right input programmed. If you are using a cable box the tv must be on channel 3 or 4. video input uses rca cables red white and yellow to the proper input on the tv but there again the input must be set correctly. Possibly in the menu do a search there. Hope this helps.