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故障现象:收看一段时间后,关机再开机,机内有“吱”的一声不能启动,有时也能启动工作,无规律。当故障出现时,测主电源+111V电压约为0V且不稳定有微小的摆动。分析与检修:根据故障现象判断为机内保护电路因某种原因处于保护状态。首先用万用表测如图1所示的保护电路可控硅Q902的G极电压为0.6V,说明
Symptoms: watch for a period of time, shut down and then boot, the machine has a “squeak” can not be started, and sometimes can start working, irregular. When the fault occurs, measure the main power + 111V voltage is about 0V and unstable swing with a slight. Analysis and Maintenance: According to the phenomenon of failure to determine the internal protection circuit for some reason in a protected state. First of all, with a multimeter to test Figure 1 shows the protection circuit silicon Q902 G pole voltage of 0.6V, that