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故障现象 IBM PC/AT 286机打开电源后,机器自检没完,扬声器无响声,显示屏全黑,即出现“死机”。 故障分析与维修 用替换法和插拔法很快发现是由于系统板出故障造成“死机”。用逻辑笔检查系统板I/O槽中的地址和数据总线,测得它们在开机后有一至两个脉冲,然后变成固定电平。地址和数据总线有脉冲,尽管之后成为恒定电平,这说明CPU已经工作,只是没执行几条指令便“死机”,CPU是好的。测得CPU及其周围电路是好的,接着测试系统总线,因为系统总线若有故障,最容易造成“死机”现象。检查总线有一个巧妙的方法:在加电之前,人为地将任意一个I/O扩
Symptom IBM PC / AT 286 machine power is turned on, the machine endless self-test, the speaker no sound, the display is all black, that “crash.” Failure Analysis and Maintenance Replacement and plug-in method is quickly found to be caused by the system board failure caused “crash.” Check the address and data buses in the I / O slots of the system board with a logic pen and measure that they have one or two pulses after power-up and then change to a fixed level. The address and data bus pulse, although after a constant level, indicating that the CPU has been working, but did not execute a few instructions will “crash”, the CPU is good. Measured CPU and its surrounding circuits is good, and then test the system bus, if the system bus failure, most likely to cause “crash” phenomenon. Check the bus there is a clever way: before the power-up, artificially any one I / O expansion