| 摘要 |
PURPOSE:To secure the protection of a fly-back transformer by making a protection circuit protecting a high voltage generating circuit for a TV receiver composed of first and second protection circuits, stopping horizontal oscillation by means of the first circuit and destructing a horizontal output transistor by means of the second circuit when the fly-back transformer is abnormal. CONSTITUTION:The high voltage generation circuit is newly provided with a second protection circuit 9. The circuit 9 consists of a diode D1 whose anode is connected to the output terminal of a horizontal synchronization deflection circuit 4, a resistor R2 connected between the cathode of the diode and the comparation voltage input terminal of a voltage comparator 5, and a capacitor C grounding the cathode of the diode D1. By such construction, when an abnormality such as electric discharge occurs, an incoming current I1 increases and electric potential V3 at point A becomes lower than a first reference voltage V2, the comparator 5 transmits a signal to stop the action of the circuit 4. When the current I1 further increases, the base drive current of a horizontal output transistor 3 is reduced to destruct the transistor 3. |
