| 摘要 |
PURPOSE:To prevent a screen from being made black by connecting a resistor between bases of both transistors (TRs) of a differential amplifier and setting the bases to almost the same potential in terms of DC in a video amplifier circuit of a color television receiver. CONSTITUTION:In setting a channel to an idle channel, no burst gate pulse appears at a terminal 13 and a base potential of a TR5 tends to fall down. Since a resistor 23, however, is connected between both bases of TRs 4, 5, the bases are brought into almost the same potential and the collector potential of the TR5 does not reach a voltage VCC applied to a DC power supply terminal 15. Thus, the differential amplifier 3 acts like differential operation and a potential appears at the base of the TR4 accordingly in response to a signal appearing via a contrast adjusting circuit 1. |
