论文部分内容阅读
(2)光电耦合器PC1、PC2分别用于检测输出的+24V和+5V变化的误差电压,耦合到初级回路,分别控制三极管Q2、Q3的导通来调节开关管Q1的关断时间,从而控制高频脉冲的宽度,以保持输出电压的稳定。+5V、+12V电压都正常,因此变换器和输入电路工作正常,故障只能在-12V电压输出电路中。-12V电压电路中的主要器件是三端稳压器IC2(μPC79M12H),用万用表分别测量IC2的输入(C14两端)电压和输出(C16两端)电压,发现输入电压正常,而输出电压为0V,由此判断IC2损坏。更换IC2后开机试验,传真机工作正常,故障排除。
(2) Optocouplers PC1 and PC2 are used to detect the output error voltages of +24 V and +5 V, respectively. Coupled to the primary circuit, the optocouplers are respectively controlled to turn on the transistors Q2 and Q3 to adjust the turn-off time of the switch transistor Q1 Control the width of the high-frequency pulse to maintain the stability of the output voltage. + 5V, +12 V voltage are normal, so the converter and the input circuit is working properly, the fault can only be -12V voltage output circuit. -12V voltage circuit is the main device is a three-terminal regulator IC2 (μPC79M12H), measured with a multimeter IC2 input (C14 both ends) and output voltage (C16 ends) voltage and found that the input voltage is normal, and the output voltage is 0V, thus determine IC2 damage. After switching IC2 boot test, fax machine is working properly, troubleshooting.