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故障现象:收看节目时,光栅突然收缩成一条水平亮线,并迅速扩展,伴音时断时续,几秒钟后自动恢复正常。这种现象有时间隔1～2小时出现一次,有时则频繁出现,以致无法收看。出现上述现象时,电源指示灯亮,节目指示灯不亮。分析检修:因为故障出现时电源指示灯亮,可断定主电源输出基本正常。而节目指示灯不亮,说明其12V供电电源有问题。用万用表直流电压档监测12V电源整流管D_(307)的负端电压,当故障出现时,12V电源立即跌为0V。换文流档监测其正端电压,故障出现时电压指示仍基本不变。关机触摸整流管很烫手,说明12V
Symptoms: watch the program, the grating suddenly shrink into a horizontal bright line, and rapidly expanding, intermittent sound intermittent, automatically return to normal after a few seconds. This phenomenon sometimes appear every 1 to 2 hours, sometimes frequently appear, so can not watch. When the above phenomenon occurs, the power indicator light, program indicator light does not shine. Analysis and Maintenance: Because the power indicator light is on when the fault occurs, it can be concluded that the main power output is basically normal. The program indicator is off, indicating that there is a problem with its 12V power supply. Use a multimeter to monitor the negative voltage of 12V power rectifier D_ (307) with DC voltage. When the fault occurs, the 12V power supply immediately drops to 0V. For file flow monitoring its positive voltage, the voltage appears when the fault indication is still basically unchanged. Turn off the touch rectifier is very hot, indicating 12V