High voltage protecting circuit

A high voltage protecting circuit in a cathode ray tube apparatus comprising:

• a main power switch connected to an electric power source;
• a flyback transformer having primary, secondary and tertiary windings;
• rectifying circuit means connected to the main power switch for rectifying a power source voltage originating from the power source and supplying a rectified voltage to the primary winding of the flyback transformer;
• switching means connected between the main power switch and the rectifying circuit and including means responsive to a control signal applied thereto for controlling the ON and OFF operating state of said switching means;
• high voltage detecting and controlling means for comparing an output voltage produced across the tertiary winding of the flyback transformer with a reference voltage and generating a control signal when the output voltage exceeds the reference voltage, said control signal switching the switching means to the OFF state;
• a standby transformer connected to the electric power source through the main power switch, said standby transformer having primary and secondary windings;
• and
• additional rectifying circuit means, and wherein the secondary winding of the standby transformer generates a voltage thereacross which is supplied through the additional rectifying circuit means to the high voltage detecting and controlling means for keeping the high voltage detecting and controlling means in an operative condition regardless of the operating state of the switching means.