My Sharp LD-23SH1U stopped working all of a sudden. One day the screen went purple with Mono 3 flashing. The cable company (TIme Warner) checked the cable connection and it was still viable. They said, my TV went "analogue.' I don't see instructions for handling this issue in the manual.
Sharp LCD LD-23SH1U - purple screen with Mono 3 flashing
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What happens when you change inputs? What does your manual say Mono 3 is?