Display unit including circuit for controlling connection to a power source based on presence or absence of a sync signal

A display unit comprising:

• a video amplifying circuit for amplifying a video signal and outputting an amplified video signal to a cathode-ray tube;
• a sync separation circuit for separating a synchronizing signal from the video signal to take out the video signal;
• a deflection circuit for allowing a sawtooth current synchronized with an output produced from the sync separation circuit to flow into a deflection coil of said cathode-ray tube;
• a high voltage circuit for receiving therein an output produced from said deflection circuit and supplying a high voltage to the cathode ray tube;
• a synchronizing signal control circuit for determining whether the synchronizing signal obtained from said sync separation circuit is present and outputting a signal indicative of the presence or absence of the synchronizing signal therefrom, said synchronizing signal control circuit having a synchronizing signal control switch for enabling supply of a signal indicative of the absence of the synchronizing signal at all times as necessary;
• a power source control circuit for opening and closing a power source circuit in response to an output supplied from said synchronizing signal control circuit;
• and
• a power switch connected to a terminal for inputting power to said display unit;
• whereby said sync separation circuit, said synchronizing signal control circuit and said power source control circuit are directly supplied with power from a power source through said power switch and at least one of said video amplifying circuit, said deflection circuit and said high voltage circuit is at least partially supplied with power from said power source circuit.