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故障现象:一台IBM/AT微机在运行过程中突然损坏。开机检查,发现市电输入保险丝烧断,末级驱动晶体管2SD1403(I_C=6A,V_(CEO)=800V,P_D=120W)损坏。在维修中,用具有类似性能的晶体管2SC3642更替后,重新开机运行大约半小时左右,微机电源又被损坏了。分析检修:如上所述在维修过程中,当更换受损的功率开关晶体管后,微机能正常运行一段较短的时间。这一事实说明IBM/AT微机电源的5V负反馈控制网络的工作基本正常。但在运行一段较短时间后,微机电源又被损坏。这说明微机电源本身仍有故障。根据
Symptom: An IBM / AT microcomputer suddenly damaged during operation. Turn on the test and found that the mains input fuse blown, the final drive transistor 2SD1403 (I_C = 6A, V_ (CEO) = 800V, P_D = 120W) damage. In the maintenance, with a similar performance transistor 2SC3642 replacement, re-run about half an hour to run, the computer power has been damaged. Analysis and Maintenance: As mentioned above during maintenance, when the damaged power switching transistor replacement, the computer can run normally for a short period of time. This fact shows that IBM / AT microcomputer 5V negative feedback control network work basically normal. But after running for a short period of time, the microcomputer power is damaged again. This shows that the computer power itself is still faulty. according to