| 摘要 |
PURPOSE:To secure the protection of the circuit and to improve the safety of a TV receiver by instantaneously cut off the relay of a main power circuit and setting it in a stand-by state when a receiver has the abnormality. CONSTITUTION:The overvoltage detecting zener diodes 4 and 5 are set at such levels where both diodes are not actuated when a TV receiver works normally. Thus the voltage is applied to the gate of a thyristor 8 when a short circuit occurs between the 1 pin and the 2 pin of a DY coupler or a collector pulse dividing capacitor 2 has a short circuit. When the voltage is applied to the gate of the thyristor 8 at occurrence of the abnormality, the thyristor 8 conducts and turns on a transistor(TR) 9. Thus a relay driving TR 10 is forcibly turned off and then a relay is also turned off. Therefore the AC voltage is not supplied to a main power circuit any more and the TV receiver main body is set in a stand-by state. |
