| 摘要 |
PURPOSE:To attain miniaturization of a flyback transformer and to protect a vertical deflection circuit at short-circuit of a DC blocking capacitor by supplying a DC power supply of a vertical deflection circuit from a switching power supply circuit. CONSTITUTION:The power supply of the vertical deflection circuit comprising transistors (TRs) 27, 29, a vertical deflection coil 30 and the DC blocking capacitor 31 is supplied from a secondary winding 10 of a switching transformer 8 via a diode 16. A voltage is applied to a base of a TR43 from the flyback transformer 20 and the TR43 is conductive and a TR41 is nonconductive normally. When the capacitor 31 is short-circuited, a constant voltage 33 is conductive, a voltage is applied to a horizontal oscillating circuit 19 from a terminal (i) to stop operation of the horizontal deflection output circuit. As a result, the TR43 is nonconductive and the TR41 is conductive, a base of the TR27 is grounded and the TR27 is made nonconductive, no current flows to the coil 30 thereby preventing damages to a CRT. |
