Computer hardware fault identification

With the popularization of computers, computers can be accessed in many cases, but computer faults are followed by software faults, most of which are hardware faults; the simplest method for software faults is to reinstall the system. However, hardware faults need to be judged and analyzed. Here we will introduce some common symptoms, causes, and solutions of hardware faults.

1. Computer Startup Process

1) First, let's take a look at the computer startup process.

(1) The Bootstrap Loader program and self-diagnosis program stored in ROM (read-only memory) are moved to RAM (random memory.

(2) As Bootstrap Loader runs, the operating system stored in the secondary memory device sends system files to RAM.

(3) execute the system file Io. sys and Msdos. sys. "Starting Windowsn98..." appears on the screen ......" .

(4) If Config. sys exists, execute it.

(5) execute the Command.com file of the system file.

(6) If Autoexec. bat exists, execute it.

(7) read the Windows Initialization Files "System. ini" and "Win. ini", and then read the Registry file.

(8) after the startup is completed, an initial screen is displayed and the operating system is running.

In this process, the rom bios of the motherboard monitors whether the hardware is abnormal, including hardware faults, wiring, and board installation. If an error occurs, the screen will show nothing and start and stop.

In this case, hardware faults may occur.

2) system startup sequence

(1) The ON-display, keyboard, and chassis lights ON the PC power supply flash.

(2) detect the video card.

(3) memory detection-memory capacity information appears on the sound screen of the beep.

(4) run the BIOS command. A brief BIOS information is displayed on the screen.

(5) detect other devices-information about other devices (CPU, HDD, MEM ...).

(6) execute the OS (operating system) initialization file-Starting Windows 98 and so on.

3) when the main board is started, a sound is generated. This sound can be used to determine the error. The sound representation varies depending on the form of the Main Board.

① Award BIOS error description

1 short: you will hear it every time you boot normally. Don't be nervous.

2 short: low fault. Go to the CMOS settings to see if no device is set to a certain type.

1 long, 1 short: if the memory is not faulty, well, you can finally change the motherboard.

1 long 2 short: Incorrect display or display card.

1 long 3 short: Incorrect keyboard controller.

1 long 9 short: The Flash RAM or EPROM on the motherboard is incorrect, and the BIOS is damaged. Try changing block Flash RAM.

Persistent sound: the memory stick is closed or damaged.

Keep ringing: the power supply and display are not connected to the display card. Check all the plugs.

Duplicate short response: power supply problems.

② Description of an ami bios Error

1 short: Memory refresh failed, replace the memory.

2 short: Memory ECC verification error. You can set the ECC check option in COMS to DISABLED. However, if an error occurs during the running of the program, you don't have to worry about it.

3 short: the system basic memory (1st 64KB) Check failed, and your memory is too low.

4 short: system clock error.

5 short: the central processor (CPU) error is rare.

6. Short: the keyboard controller is incorrect.

7. Short: The system real-time mode is incorrect and cannot be switched to the protection mode.

8 short: Memory read/write failure. Sometimes this problem occurs after the video is added.

9 short: rom bios check error. Unfortunately, your BIOS chip may be damaged, and the general "Hot swapping" and other methods cannot solve this problem. Only New BIOS blocks can be changed. Of course, you can also change the motherboard.

10 short: read/write errors in CMOS shutdown.

11. Short: Cache storage errors. if you can tolerate the speed of turtles, you can select the Cache settings as Disable in CMOS.

1 long 3 short: memory error.

1 long, 8 short: The test error is displayed. The display data line is not plugged in or the display card is not plugged in.

③ Phoenix BIOS self-check announcement meaning

1 short: normal system boot

3 short: system power-on self-check initialization (POST) failed

1 short 1 short 2 short: Incorrect Motherboard

1 short 1 short 3 short: motherboard battery unavailable or CMOS damaged

1 short 1 short 4 short: rom bios check error

1 short, 2 short, and 1 short: the real-time clock of the system is faulty.

1 short 2 short 2 short: DMA channel initialization failed

1 short 2 short 3 short: DMA channel page register error

1 short 3 short 1 short: memory channel refresh error (problem scope: all memory)

1 short 3 short 2 short: basic memory error (memory corruption or RAM setting error)

1 short 3 short 3 short: basic memory error (probably due to memory corruption on the DIMMO slot)

1 short 3 short 4 short: Sub-Interrupt Processing Register Error

1 short, 4 short, 1 short: An error occurred at an address in the basic memory.

1 short 4 short 2 short: the system basic memory (1st 64 K) has a parity error

1 short 4 short 3 short: eisa bus sequencer Error

1 short 4 short 4 short: eisa nmi port error

2 short 1 short 1 short: the system basic memory (1st 64 K) Check failed.

3. Short: 1. Short: 1st DMA controllers or register errors

3 short 1 short 2 short: 2nd DMA controllers or register errors

3 short 1 short 3 short: Master Interrupt Processing Register Error

3 short, 2 short, 4 short: Incorrect keyboard clock. Reset it to Not Installed in CMOS or skip POST.

3 short 3 short 4 short: the RAM on the display card has an error or no RAM, not a fatal error

3 short, 4 short, 2 short: the display data cable is loose, the display card plug is unstable, or the display card is damaged.

3 short, 4 short, 3 short: no display card rom bios found

4 short, 2 short, and 1 short: Real-time clock error of the system

4 short 2 short 2 short: system startup error, improper CMOS settings or BIOS damage

4 short, 2 short, 3 short: the Gate A20 switch in the keyboard controller (8042) is incorrect, and the BIOS cannot switch to the protection mode.

4 short, 2 short, 4 short: protection mode interruption Error

4 short 3 short 1 short: memory error (memory corruption or RAM setting error)

4 short 3 short 3 short: system second clock error

4 short 3 short 4 short: Real-time clock error

4 short, 4 short, 1 short: Serial Port (comport, mouse port) Failure

4 short, 4 short, 2 short: Parallel Port (LPT port, parallel port) Error

4 short, 4 short, 3 short: Digital coprocessor (8087, 80287, 80387, 80487) Error

This is basically the meaning of common BIOS self-detection. For other BIOS information, see relevant information.

2. obfuscated software faults

It is necessary to clearly distinguish between hardware faults and software faults, especially startup faults, which may also be caused by software faults. Let's take a look at the startup exceptions caused by software faults.

1) CMOS Setup Error

If the hard disk settings in CMOS Setup are incorrect, the hard disk cannot be started with the operating system (Windows) in the hard disk because the computer cannot identify the hard disk. Check the content of CMOS Setup when the image appears but cannot be started. To correctly identify the hard disk, you can use the "ide hdd Auto Detection" option in CMOS Setup.

2) System File errors

When Windows is started, four files, Command.com, Io. sys, Msdos. sys, and Drvspace. bin, are required. If these files are damaged, they cannot be started even if the hard disk is identified. You can use the "Sys.com" file to restore these files. After starting with the boot disk, type "Sys c.

3) file initialization error

Windows reads "Autoexec. bat "," Config. sys "," System. ini "," Win. ini "," User. dat "," System. dat. However, if an error occurs during reading, the startup will fail. These files are difficult to recover, so you need to use methods such as Windows resetting, but this is not a hardware fault.

4) Windows errors

Most of the faults on the Windows initial screen are software faults. Conflicts between programs or driver issues. This problem can be solved by reading books and other methods.

3. hardware faults that are not faulty

Although it is not a fault, user assembly is often incorrect or the plug-in is loose. In this case, you can turn on the computer to check the wiring and plug-in errors. When purchasing new hard drive, CD-ROM and other EIDE devices, be sure to set the device in the middle to "SlaveE", set the device connected to the edge to "Master ", an error may occur when the device cannot be started or used if the device is set incorrectly.

4. hardware fault detection method

Next, let's take a look at the basic test methods for hardware faults. When the monitor does not have any image, you can use the following method to test the faulty part.

(1) Prepare a workbench first.

(2) unplug the motherboard from the chassis, and then unplug all the components on the motherboard, leaving only the CPU and RAM, and then place the motherboard on the workbench.

(3) connect the regulated power supply to the motherboard.

(4) Insert the video card into the AGP slot. Of course, if it is a PCI graphics card, it is inserted into the PCI slot. When inserting a video card, make sure that the gold-plated part of the video card is completely inserted into the slot.

(5) connect the video card to the monitor after connecting the power plug-in of the monitor.

(6) turn on the power of the monitor, and then turn on the power switch of the chassis. Then use a metal rod to access the power switch of the motherboard. The POWER switch of the motherboard is the part connected to the POWER switch of the chassis, which is generally marked as "pwr sw" or "power se ".

(7) If the BIOS version information is displayed on the screen and the screen is normal, the CPU, motherboard, RAM, video card, and power supply are normal. Generally, the component that is prone to failures is in the order of "graphics card", "motherboard", and "Hard Disk.

If you have a motherboard diagnosis card, you can quickly identify the components that are faulty based on the characters displayed. The general practice is to insert the diagnosis card into the PCI or IAS slot of the motherboard and start the system. At this time, the diagnosis card will run the code. If the diagnosis card code runs 00 or FF, it indicates that the CPU has not started to work, which is generally a problem with the CPU or motherboard; code running from 00 FF to C1 or D3 (different BIOS running Code may not be the same) indicates that the CPU is good. The problem is that the memory is not working, and the memory golden finger or slot is dirty, or the working conditions provided by the main board to the memory are insufficient, that is, the main board may be broken; the Code ran from 00 FF to 26. Generally, if there is no problem with the video card and the main board, the display should be lit up; if the code runs from 00 FF to 41 and the host is not bright, it is very likely that the BIOS is broken, and you need to refresh or change the BIOS. After 00 FF code passes CI C3 05 07 13 26 (0B) 41 43 and so on, the diagnosis card runs back to 00 or FF again, indicating that the startup process of the motherboard is complete, start to boot according to the CMOS settings.

(8) connect the hard disk and the soft area for detection. Connect the CD-ROM detection, then the sound card. Modem and other connections. If no picture is displayed, it indicates that the connected component is faulty or has compatibility problems. Only the faulty part must be processed.

(9) Chassis Problems

Sometimes an error occurs when installing the motherboard to the chassis, causing startup failure. Therefore, if there is no problem in the above part check, you can install the motherboard on the chassis for testing. If there are no errors in the test, it indicates a CMOS Setup error, a driver, and other software problems.