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故障现象:打开传真机电源开关,传真机显示窗口无显示,面板的所有指示灯均不亮,整机无动作。分析检修:据用户反映,该传真机无任何随机资料。从传真机底部的铭牌看,该机是日本电信电话株式会社生产的,属普及型产品。根据故障现象,首先应查传真机的电源部件。拆开传真机的塑料外壳,取出电源部件,发现电解电容C_7顶部崩裂,交流输入保险丝完好,其他元件未见异常。遂用200V/680μF的电容更换C_7后,开机故障依旧。从传真机电源部件的元器件排列看,该机电源是低通滤波。启动保护、桥式整流等电路与IBM/PC微机电源相似,其启动保护和整流滤波电路如图1所示。
Symptom: Turn on the fax machine power switch, fax machine display window no display, all the panel lights are not bright, the whole no action. Analysis and Maintenance: According to user feedback, the fax machine without any random information. From the bottom of the fax machine nameplate, the machine is produced by Japan Telecom Tel Co., Ltd., is a popular product. According to the symptoms, first check the fax machine power components. Open the plastic case of the fax machine, remove the power components and found electrolytic capacitor C_7 top crack, AC input fuse intact, other components without exception. Then use 200V / 680μF capacitor replacement C_7, boot failure still. From the facsimile power supply components of the component arrangement, the machine power is low-pass filter. Start protection, bridge rectifier circuit and IBM / PC microcomputer power similar to its start-up protection and rectifier filter circuit shown in Figure 1.