Abstract: The invention tests the operation of a CRT X-ray protector circuit without applying an abnormally high voltage to the CRT. In addition to a first reference voltage corresponding to the detected voltage which is the standard for the operation of the X-ray protector for use in a display device with the CRT, a second reference voltage set at a value lower than the first reference voltage and higher than 0 V is provided to enable the operation of the X-ray protector circuit by comparing the detected voltage with the second reference voltage at the time of testing the X-ray protector circuit's operation. A third reference voltage, higher than the first reference voltage, is compared to the detected voltage during channel switching or external input switching to prevent erroneous activation of the x-ray protector.

Abstract: Apparatus and method which commands the displaying of audio information on a television receiver display in the case where it is judged that a sound muting control unit was operated, whereby the audio information is displayed by a single operation of the sound muting control unit.