重要的电脑维修常识.doc

1.維修一般流程一般來說,維修人员拿到一塊功能不良板時,不要急于動用維修設備,首先全面目測M/B看是否有嚴重的外觀問題,如連錫,虛焊或明顯的斷線等,如果有相應現象,則可以減少大量的維修時間(指維修該板的時間)及不必要的物料損耗.如果目測無發現問題,則看明維修流程卡的所寫的故障現象,接著根据故障插上相應的維修設備,針對無顯示的M/B,最好先不插CPU(謹防由于CPU的工作電源過高而燒毀CPU),先用示波器或万用表測量CPU的工作電壓是否正常,等正常后再插CPU驗証故障現象,然后根据現象查相關電路圖,測量相關信號.直至查出故障的原因.維修中不涉及BGA的元器件一律自己更換,凡是涉及到要更換BGA的功能不良板則由專門的操作員更換.在更換芯片時應注意芯片的方向,在測試之前,應檢查焊過的芯片是否有虛焊,短路之現象M/B上所有動過烙鐵的區域應嚴格用制定的清洁濟清洗並用抹布擦干,在送測試之前應仔細檢查是否有損件,殘留物,錫渣,錫尖等外觀問題,提高維修效率 2.M/B 一般架构：3.M/B的數据.地址流向:a. 地址流向：BIOS HA AD SA 87570SBNBCPU b. 数据流向： BIOS87570SBNBCPU HD AD SD 4. 微机的開机過程 整個微机的開机過程分為硬件啟動和軟件啟動硬啟動是指POWER的動作過程而軟啟動部分是指BIOS的POST過程先是硬件啟動而后是軟件啟動了解微机的開机過程,對主板功能維修是很重要的,因為很多功能不良板特別是當机板,可以根据開机的順序從而判斷系統哪部分有問題a. 硬件起动过程（Power sequences）: Hardware Power Block Diagram b. 软件起动过程(POST)：RESETInterrupt vector initialization to begin.To clear password if necessary.NMI is Disabled.CPU ID saved.Init code Checksum verification starting.POST code to be uncompressed.CPU init and CPU data area init to be done.Any initialization before setting video mode to be done.To do DMA init,Keyboard controller test,start memory refresh and going to 4GB flat mode.CMOS checksum calculation to be done next. Differrent BUSes init (system,static,output Devices) to start if present.To start Memory sizing.Keyboard command byte to be written.To look for optional Video ROM and give Control.To comeback to real mode.Execute OEMPatch.set stack.To init CMOS if “Init CMOS is every boot”is set or key is pressed.Going to disable DMA and Interrupt controllers.If EGA/VGA not found then do display Memory R/W test.E000 ROM enabled.Init code is copied to segment 0 and control to be transferred to segment 0 .Display memory R/W test passed.About toLook for the retrace checking.Video display is disabled and Port_B is Initialized.Chipset init about to begin.Control is in segment 0. To check key and verify Main BIOS checksum.Display different BUSes initialization error message.8254 timer test about to start.To pass control to Interface Module.DMA test and initialize 8259 interrupt.About to start memory refresh test.NMI is Disabled.To check soft reset/power-on.Keyboard test started.clearing output buffer,checking for stuck key,to issue keyboard reset command.To read 8042 port input port POST Flow Char Next PageInitialization after E000 optional ROMControl is over.Going to display the System configuration.Any initialization required after optional ROM test over.going to setup timer data area and printer base address.Keyboard controller interface test over.to Write command byte and init circular buffer.Command byte written,Global data init done. To check for lock-key.To uncompress DMI data and execute DMI POST init.Return after setting timer and printer base address.going to set the RS-232 base addressLock-key checking over.To check for memory size mismatch with CMOS.System configration is displayed.Going to display any soft errors.Programming before setup complete.To uncompress SETUP code and execute CMOS setup.Going to copy any code to specific area.Soft error display complete.Going to set keyboard typematic rate.Setup options programming after CMOS Setup about to start.Copying of code to specific area done.Going to give control to INT-19 bootloader.Going to enable parity/NMI.NMI and parity enabled.Going to do any initialization required before giving control to optional ROM at E000.Going for hard disk controller reset.INT-19 bootOSHard disk controller reset done. Floppy setup to be done next.Initialization before E000 ROM control over.E000 ROM to get control next.Floppy setup complete.Hard disk setup to b