| 摘要 |
PURPOSE:To protect CRT and to prevent overload of the horizontal output circuit, by stopping the operation of the horizontal circuit at a failure of flyback pulse and outputting the switch element with overcurrent at failure detection part. CONSTITUTION:The power supply input terminal 2a is grounded via the thyristor 10, the zener diode 18 is conducted only when the high voltage applied to CRT6 is excessively high, and the thyristor 10 is conducted by giving trigger signal to the gate of the thyristor 10 via the diode 22. Thus, the power supply voltage of the horizontal oscillation circuit 2 is lowered to the chassis potential through the resistor 12 and the thyristor 10 to stop horizontal oscillation. Further, the flyback pulse obtained from the secondary winding 5a is fed to the non-charging circuit 25 through rectification and smoothing with the diode 23 and the capacitor 24. If the circuit 25 is in short circuit failure, the horizontal circuit is overloaded, the power supply current is increased. When the voltage across the small resistor 26 exceeds a given value, the switching transistor 27 is conducted. Thus, the thyristor 10 is conducted and the voltage supply to the circuit 2 is stopped to avoid overload. |
