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故障现象:烧一会儿全无,等待状态的指示灯亮,各功能键均失灵。分析与检修:此机型的供电是220V交流电压先经遥控板上的遥控变压器,即由付电源供电电路产生的+5V电压供给微处理器N_(901)(M50436—560SP)使其工作,然后由N_(901)输出约5V电压使继电器K_(901)吸合,220V交流电压才进入主电路板。从故障的现象看,故障部位在遥控电路板上。因此,先测遥控板上-30V供电电压,正常;再测+5V供电电压为+2.1V,偏低。断开+5V负载后,+5V电压恢复正常,说明+5V电路的负载重,存在着热击穿现象。+5V供电分三路,可分三步进行查找。 (1)断开存储器N_(902)(M58655P)的①脚后,测
Symptoms: no burning for a while, waiting for the status indicator light, the function keys are malfunctioning. Analysis and Overhaul: The power supply of this model is 220V AC voltage first by the remote control transformer on the board, that is, by the power supply circuit to produce a +5 V voltage supply to the microprocessor N_ (901) (M50436-560SP) to make it work, Then by the N_ (901) output of about 5V voltage pull the relay K_ (901), 220V AC voltage before entering the main circuit board. From the phenomenon of failure, fault location in the remote control circuit board. Therefore, the first test remote control board -30V supply voltage, normal; retest + 5V supply voltage is + 2.1V, low. After disconnecting the +5 V load, the +5 V voltage returns to normal, indicating that the load of the + 5V circuit is heavy and there is a phenomenon of thermal breakdown. +5 V power supply in three ways, can be divided into three steps to find. (1) Disconnect the memory (902) (M58655P) ① feet and measure