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1.一台286机开机后,检测内存正常,显示“PressIf you want run SETUP or DEAGS”后便死机。 该机主板为HT12型,从故障现象看,首先怀疑是CMOS信息丢失,但此时无法进入CMOS进行配置检查,继而怀疑是ROM芯片有问题,换上同型号二片ROM,故障依旧。用示波器观看波形,发现芯片COMS的第14脚恒为低电平,仔细检查发现芯片CMOS HM6818P的第14脚至控制芯片HT12P-16/A的第84脚中间有一连接孔被CMOS电池腐蚀。该连接孔在芯片KEYBOARD BIOS底下,不易发觉,用酒精擦除蚀斑,然后补焊,机器恢复正常。此种型号主板上的CMOS电池质量较差,经常漏电,腐蚀电路,笔者曾多次维修过这种型号的主板,都是因此种原因造成各种故障。 2.一台286机开机后,扬声器发出“一长八短”响声,显示器显示字符零乱,并伴随跳跃。
1. A 286 machine boot, the test memory is normal, “Press If you want to run SETUP or DEAGS” after the crash. The aircraft motherboard HT12 type, from the breakdown of the phenomenon, the first suspect is the loss of CMOS information, but at this time can not enter the CMOS configuration check, and then suspected ROM chip problems, put on the same type two ROM, the fault still. Watch the waveform with an oscilloscope and found that the 14th pin of COMS pin is always low. Check carefully that the 14th pin of chip CMOS HM6818P is corroded by CMOS battery in the middle of the 84th pin of control chip HT12P-16 / A. The connection hole in the chip KEYBOARD BIOS under, not easy to find, erasing plaque with alcohol, and then welding, the machine returned to normal. This type of motherboard CMOS battery quality is poor, often leakage, corrosion of the circuit, I have repeatedly repaired this type of motherboard, are due to various reasons cause a variety of failures. 2. A 286 machine boot, the speaker issued a “long, short” sound, the display shows chaotic characters, and with the jump.