| 摘要 |
PURPOSE:To set the driving condition of a horizontal output transistor at an optimum value, by switching the primary winding tap of a horizontal driving transformer corresponding to a horizontal deflection frequency. CONSTITUTION:A midpoint tap is drawn out from the primary winding 6a of the horizontal driving transformer 6 in a horizontal driving circuit 3, and a change-over switch 12 to switch a termination tap and the midpoint tap is provided. A horizontal synchronous frequency separated and supplied from the input side of a horizontal oscillation circuit 2 is converted to a voltage signal at a frequency-voltage conversion circuit 13. When the voltage signal exceeds a regulated value, in other words, when the horizontal synchronous frequency exceeds a reference frequency, the switch 12 is switched to the side of the termination tap. As a result, it is possible to set the static bias energy of the horizontal output transistor at the optimum value corresponding to the horizontal deflection frequency.
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