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故障现象:据用户反映,在收看过程中。突然变成“三无”,因红色电源指示灯仍发亮,用户认为是自动关机,但不管怎样用本机按键和遥控器按键,无法开机。分析与检修:电源指示灯发亮,说明故障范围在主开关电源或行输出电路中。首先检测了开关管V901和行输出管V402的集电极对地正、反向电阻,均大于5 kΩ(属正常),按以往的维修体会,这两部分电路(主、副电源)不存在明显的直流短路故障,可以通电试机进行关键测试点的电压
Symptom: According to the user reflects in the viewing process. Suddenly become “three noes” because the red power light is still lit, the user that is automatically shut down, but no matter how the machine keys and remote control buttons, can not boot. Analysis and troubleshooting: Power indicator light, indicating the fault range in the main switch power supply or line output circuit. First detection of the switch tube V901 and row output tube V402 collector positive and negative resistance, are greater than 5 kΩ (normal), according to the previous maintenance experience, the two parts of the circuit (the main and secondary power) is not obvious DC short-circuit fault, you can power test machine to test the voltage of the key points