Thanks to all who responded. The problem was indeed as most suggested: weak signal going to the tuner. I did some re-wiring lately and the cable going to my bench is coming from a splitter. To other TVs, this did not make any difference. But for some, especially combo units, it did make a difference. It appears that a certain signal strength is required for the switching action to take place between TV and Video. Bill Help make your TechAssist online repair tips database better! Submit your fixes here: http://www.circuitwork.com/techassist/tip/#tips To unsubscribe write to: techassist-request@xxxxxxxxxxxxx with unsubscribe in the subject line.