"Mode Not Supported" usually indicates that the incoming signal isn't supported due to a resolution issue. Try changing the output resolution signal of whatever is connected to Component 3 through the menu of that peripheral. (ie: if it's a cable box, use the cable box's remote to go to Picture Settings in the cable box and change the output resolution).
I don't recommend going into the service menu if you're not a trained technician or a professional calibrator.
I have a Samsung 56" DLP Model# HLN567WX/XAA that suddenly started having problems. When I turn the TV on I can hear audio as the lamp warm?s up but as soon as the picture comes on; the screen turns blue with an error message reading; Component 3 "Not Supported Mode".
In reviewing this problem I came across an article that suggests that you punch in a code to reset the lamp hours. I tried this other day and when I punched in Mute 1; 8; 2; power; I was able to get a picture and sound. The TV worked for a couple of days until last night when in the middle of a show the picture and audio disappeared and all I get is the blue screen with "Not supported mode" on it. I have tried the Mute 1; 8; 2; power thing a couple of times to no avail.
Not sure what to try next. Any help would be greatly appreciated.