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上海电视一厂最近推出的金星 C-472型47cm彩色电视机,在许多方面作了改进。其中,伴音中频系统、图象解码系统和场扫描输出电路改动较大,现逐一介绍。一、伴音中频系统伴音中频系统的特点是采用双差分鉴频器,伴音音量调节采用了直流控制方式。图1是伴音中频系统线路图。在图象中放集成电路 IC201检波时,产生的6.5MHz 第二伴音中频信号,通过陶瓷滤波器 MF401,输入到 IC401的(14)脚,(?)脚则是两个差动输入端的另一端,经 C_(405)交流接地。在限幅中放中,被去除寄生调幅的方波信号,经
Shanghai TV a factory recently introduced Venus C-472 47cm color TV, in many ways made improvements. Among them, audio intermediate frequency system, image decoding system and field scanning output circuit changes larger, are introduced one by one. First, the sound system IF audio Intermediate frequency system is characterized by double differential frequency discriminator, audio volume control using DC control. Figure 1 is a sound intermediate frequency system circuit diagram. IC201 in the image signal processing IC201 generated, the second intermediate frequency signal 6.5MHz produced by the ceramic filter MF401, input to IC401 (14) feet, (?) Foot is the other end of the two differential inputs , The C_ (405) AC ground. Placed in the limit, the square wave signal is removed parasitic amplitude modulation