Basic Methods of Computer Repair
1. Inspection Method
Inspection is the first essential method in the repair diagnosis process, running throughout the entire repair process. Inspection must be thorough and comprehensive. The contents to inspect include:
1) Surrounding environment;
2) Hardware conditions, including connectors, sockets, and slots;
3) Software conditions;
4) User operation habits and processes.
2. Minimum System Method
The minimum system refers to the most basic hardware and software environment required from a repair diagnostic perspective to enable the computer to start or run. There are two forms of the minimum system:
Hardware Minimum System: Composed of power supply, motherboard, and CPU. In this system, there are no signal line connections, only the power connection from the power supply to the motherboard. During the diagnostic process, sound is used to determine whether the central components can function normally;
Software Minimum System: Composed of power supply, motherboard, CPU, memory, graphics card/display, keyboard, and hard drive. This minimum system is mainly used to determine whether the system can boot and run normally.
Regarding the software minimum environment, the following points about "software" need explanation:
1) The software environment on the hard drive retains the original software environment, which is isolated (such as uninstalled or shielded) during analysis and diagnosis. Retaining the original software environment is mainly for analyzing and diagnosing issues related to application software;
2) The software environment on the hard drive has only a basic operating system environment (which could be achieved by uninstalling all applications or reinstalling a clean operating system). Then, according to the needs of analysis and diagnosis, necessary applications are loaded. A clean operating system environment is needed to diagnose system issues, software conflicts, or conflicts between software and hardware;
3) Under the software minimum system, appropriate hardware can be added or modified as needed. For example: When diagnosing boot problems due to an unbootable hard drive, you can check if booting from another drive is possible by adding a floppy drive or replacing the hard drive with a floppy drive under the software minimum system. Similarly, when diagnosing audio/video issues, a sound card should be added to the software minimum system; when diagnosing network problems, a network card should be added.View Mirror
The minimum system method primarily determines if the system can function normally under the most basic software and hardware environment. If it cannot function normally, then the most basic software and hardware components have faults, thus isolating the fault.
Combining the minimum system method with the incremental method can quickly locate faults occurring in other board-level software, improving repair efficiency.
3. Incremental/Removal Method
The incremental method involves starting with the minimum system, each time adding only one component/equipment/software, checking if the fault disappears or changes, thereby diagnosing and locating the faulty area.
The removal method operates conversely to the incremental method.
Generally, the incremental/removal method needs to be combined with the exchange method to accurately locate the faulty area.
4. Isolation Method
This is a diagnostic method that shields hardware or software that may interfere with fault diagnosis. It can also be used to isolate suspected conflicting hardware/software to see if the fault changes.
The mentioned shielding of hardware and software refers to stopping their operation or uninstalling them for software, and disabling/uninstalling drivers or directly removing hardware from the system for hardware.
5. Exchange Method
The exchange method uses good components to replace potentially faulty ones to determine if the fault disappears. Good components can be of the same model or different models. The order of exchange generally follows:
1) Based on the fault symptoms or fault categories in part two, consider which components or equipment need to be exchanged;
2) Follow the order of simple to complex exchanges. For example: Start with memory and CPU before the motherboard. Or when diagnosing print faults, first consider if the print driver is problematic, then if the print cable is faulty, and finally if the printer or parallel port is faulty;
3) First check the connecting cables and signal lines connected to the suspected faulty components, then exchange the suspected faulty components, next exchange the power supply components, and finally other related components;
4) Consider exchanging components based on their failure rates. Components with higher failure rates should be exchanged first.
6. Comparison Method
Similar to the exchange method, the comparison method compares good components with suspected faulty ones in terms of appearance, configuration, and operational phenomena. Comparisons can also be made between two computers to identify differences in environmental settings and hardware configurations, thereby locating the faulty area.
7. Heating/Cooling Method
During on-site service, due to tool limitations, the application of the heating/cooling method differs from that in a repair shop. In on-site services, the heating method can involve reducing the ventilation of the computer with user consent to increase its temperature through self-heating; cooling methods include: 1) Choosing times with lower environmental temperatures, such as early morning or late evening; 2) Shutting down the computer for 12~24 hours; 3) Using fans to blow on the faulty machine to speed up cooling.
8. Knocking Method
The knocking method is generally used when suspecting contact issues within the computer. By vibrating, slightly bending, or even using a rubber hammer to tap specific components or equipment, the fault can be reproduced, thereby identifying the faulty component.
9. Suggestion for Cleaning Computer Products
Some computer faults are often caused by excessive dust inside the machine. Therefore, during repairs, attention should be paid to observing whether there is too much dust inside and outside the faulty machine. If so, cleaning should be done first before further diagnostics and repairs. During the cleaning process, the following aspects should be particularly noted:
1) Pay attention to cleaning the air ducts;
2) Pay attention to cleaning the fans;
After cleaning the dust from the fans, it's best to apply a little clock oil on the fan shaft to enhance lubrication;
3) Pay attention to cleaning the connectors, sockets, slots, and gold fingers of the expansion cards;Glass Bottle Factory
Gold finger cleaning can be done with a rubber eraser or alcohol wipes;
Removing oxidation from the metal pins of connectors, sockets, and slots can be done by wiping with alcohol or gently scraping with a metal sheet (like a small flathead screwdriver);
4) Pay attention to cleaning the pins of large-scale integrated circuits and components;
While cleaning, use a small brush or vacuum cleaner to remove dust, and observe if there is any poor soldering or moisture on the pins, and if components are deformed, discolored, or leaking liquid;
5) Pay attention to the cleaning tools used;
Cleaning tools must be anti-static. For instance, small brushes used for cleaning should be made of natural materials, avoiding plastic brushes. Additionally, if metal tools are used for cleaning, the power must be off, and the metal tools must be treated to discharge static electricity;
Tools for cleaning include: small brushes, bulb dusters, vacuum cleaners, cloths, alcohol (not to be used on the plastic casing of the case or monitor);
6) For relatively humid conditions, find ways to dry them before use. Tools like electric fans or hairdryers can be used, or let them air-dry naturally;
10. Several Methods and Suggestions for Software Debugging
1) Operating System Aspect.
Key adjustment content includes startup files, system configuration parameters, component files, and viruses.
Repairing operating system startup files.
1) For Windows 9x systems, the sys command can be used for repair (ensuring msdos.sys is larger than 1kb), but it requires that partition parameters are correct beforehand. This can be achieved using software like diskmap;
2) For Windows 2000/xp systems, there are two methods—repairing startup files using the fixboot command; repairing the master boot record using the fixmbr command.
Adjusting operating system configuration files.
a. For Windows 9x systems, many tools can be used, such as: the msconfig command, system file checker, registry backup and restore commands (scanreg.exe, which runs in DOS. Also, if using scanreg.exe to restore the registry, it’s best to use the second backup file listed in the restore menu);
b. For Windows 2000 systems, fewer tools are available compared to Windows 9x, but some debugging commands can be used from Win98 (like the msconfig command from Win98, which can be used in Windows 2000);
c. For Windows XP systems, the main tool available is the msconfig command;
d. Adjusting power management and related services can be done by entering gpedit.msc in the "Run" dialog box;
e. All operating system debugging can be done through the control panel, device manager, and computer management (not available in Windows 9x systems).
Repairing component files (including .dll, .vxd, etc.)
a. Reinstalling via the add/remove sequence;
b. Installing by extracting from .cab files;
c. Using the system file checker (sfc.exe command) to repair companion files;
d. Copying and overwriting from a good machine.
Checking for viruses in the system.
It is recommended to use antivirus software in command-line mode that can directly access partitions like NTFS.
2) Device Driver Installation and Configuration.
Mainly adjusting whether the device driver sequence matches the device, whether the version is suitable, and whether the corresponding device responds normally under the driver sequence.
a. Preferably, let the operating system automatically recognize first (unless special requirements exist, such as specific display card drivers, sound card drivers, non-PnP device drivers, etc.), then consider forced installation. This helps in determining the condition of the device;
b. If the operating system has built-in drivers, use them first. If they still do not work properly or meet usage needs, use the device's own drivers;
c. When changing devices, uninstall the driver first before replacement. Uninstallation can be done from the device manager, then from safe mode, then by deleting in the inf directory, and finally through the registry;
d. When updating drivers, if direct upgrades cause issues, uninstall first before updating.
3) Disk Status.
Check if the partitions on the disk can be accessed, if the media is damaged, and if the files stored on it are complete.
Available adjustment tools:
a. Diskmap, conveniently retrieving the correct partition;
b. Fdisk and fdisk /mdr, checking if the partition is correct and restoring the master boot record to its original state;
c. When the hard disk capacity exceeds 64GB, if repartitioning or checking the partition is required, use the fdisk command from the disk partition floppy disk provided with the system. This command can be replaced by the fdisk command from Windows ME;
d. Format, scan_disk, and manufacturer-provided disk inspection sequences, checking if the disk media has bad sectors;
e. When files are incomplete, rename the incomplete files first, then rebuild using the methods described in the "Operating System Aspect".
4) Application Software.
Whether the application software is compatible with the operating system or other applications, whether the usage and configuration match what is stated in the manual, and whether the relevant sequences and data of the application software are complete, etc.;
5) BIOS Settings.
1) Restore to optimal status when necessary. Recommendation: During repair, first restore the BIOS to optimal status (usually the factory settings), then gradually set it to appropriate values based on usage needs.
2) BIOS updates do not necessarily need to be updated to the latest version; sometimes, downgrading versions should be considered.
6) Rebuilding the System.
When hardware configuration is correct and user permission is obtained, system software faults can be diagnosed by rebuilding the system. When the user does not agree, it is recommended to use a self-brought hard drive for system rebuilding operations. In this situation, after rebuilding the system, it is best to gradually restore to the original state of the user's hard drive to identify the fault point.
1) Rebuilding the system should primarily be done using one-key restoration, followed by restoration installation, and lastly, complete reinstallation. Restoration installation method:
For Windows 9x systems, direct installation from the CD-ROM or executing tools, sysrec, pcrestor.bat will achieve restoration installation. During restoration installation, the presence of win.com might affect the normal installation process. In this case, delete win.com from the Windows directory and reinstall.
Another restoration installation method involves renaming system.1st in the root directory to system.dat, overwriting the same-name file in the Windows directory, and then restarting. However, this method is not a true reinstallation but similar to a complete reinstallation.Industrial Ceramics
For Windows XP or Windows 2000 systems, directly boot from the installation CD, choose repair installation in the installation interface. Choosing 'R' will present two options: one is quick repair for simple problems; the other is the fault recovery console, which can be activated by choosing the correct installation directory. The fault recovery console interface resembles a DOS interface.
2) To ensure a clean system, execute the fdisk /mbr command (or clear.com) before installation. If necessary, execute the format /u [/s] command afterward.
3) Make sure to use the random version or genuine operating system installation medium for installation.