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故障现象:开机“三无”,红、绿指示灯均亮;能听见机内继电器吸合随即又释放的声音。按遥控器上“开/关机”键,第一次绿指示灯灭,机内无反应;第二次绿灯再亮,可再次听见继电器吸合与释放声。分析与检修:接机时,笔者并不急于维修,而是对该故障进行了全面分析,这也是笔者一贯坚持的原则(编者按语:这一原则很好,值得学习和提倡)。继电器的不正常动作表明该故障与待机电路有关,该机开机与待机的实现是依靠CPU(M34300N4)控制继电器接通和断开主开关电源来完成的。其继电器的控制方式设计较有特色,吸合控制电压与保持吸合控制电压分别由两部分电路供给,其工作原理如图1所示。接通电
Symptom: boot “three no”, red, green lights are bright; can hear the relay pull the machine and then release the sound. Press the “on / off” button on the remote control, the first green light off, the machine no response; the second green light again, you can hear the relay pull and release the sound again. Analysis and Overhaul: When I was picked up, the author was not in a hurry to repair. Instead, I conducted a thorough analysis of the fault. This is also the principle I have consistently adhered to (Editor’s Note: This principle is very good and worth learning and advocating). The abnormal operation of the relay indicates that the fault is related to the standby circuit. The start-up and standby of the machine are realized by turning on and off the main switch power supply by the CPU (M34300N4) control relay. The relay control design is more distinctive, pull-in control voltage and pull-in control voltage are supplied by two parts of the circuit, the working principle shown in Figure 1. Turn on the electricity