The television turns off when turning off a cable or satellite set-top box.
If the television powers down when the cable or satellite set-top box is turned off, then the power cord of the TV is plugged into an AC outlet on the set-top box. When the set-top box is turned off, it discontinues power to the television. Unplug the television power cord from the set-top box and plug it directly into an electrical wall outlet to resolve this issue.