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例一故障现象开机无光无声,主机箱上的电源指示灯也不亮,好象没电一样。分析与处理开机后无光无声,而且主机箱上的电源指示灯也不亮,原因有两个:(1)开关电源有故障;(2)主机板或软、硬驱有严重短路,其中后者的可能性远小于前者。取下电源与主板、软驱、硬盘的连线,然后用万用表接到+5V的输出上再开电源,发现表的指针一点儿也不动,证实为电源损坏(有些电源有空载保护,即空载时无输出,但开机瞬间输出端肯定是有输出的)。取下电源,打开外盖,发现电源内的保险管炸裂,此现象表明电源存在严重的瞬间短路故障,短路的元件主要有交流滤波电容、220V整流桥、功率开关管等。换一
Example of a fault phenomenon boot soundless, the main chassis on the power light is not bright, as if no electricity. Analysis and processing After the boot light and silent, and the main chassis on the power light is not bright, there are two reasons: (1) the switching power supply is defective; (2) the motherboard or soft and hard drives have serious short circuit, which after The possibility is far less than the former. Remove the power supply and the motherboard, floppy drive, hard drive connection, and then use the multimeter to receive +5 V output on the power supply and found that the table pointer does not move, confirmed that the power supply is damaged (some power supply with no load protection, that is No-load no output, but the boot instantaneous output is certainly there is output). Remove the power, open the cover and found the fuses inside the power burst, this phenomenon indicates that there is a serious transient short-circuit power failure, short circuit components are mainly AC filter capacitor, 220V rectifier bridge, power switch and so on. Change one