Nowadays, the integration of the motherboard is getting higher and higher, and it is more and more difficult to maintain the motherboard, so it is often necessary to use special digital detection equipment. But some common motherboard failures can be solved by themselves without special testing equipment. The following are some typical examples of mainboard fault maintenance. I hope you can learn the basic methods to solve the mainboard fault.
First, there is no display failure when starting the machine.
Example 1: The motherboard doesn't start, it doesn't display when it starts, and there is a memory alarm sound ("beep").
Cause of failure: Memory alarm failure is common, mainly caused by poor memory contact. For example, the memory stick is not standardized, the memory stick is a little thin, and there is a certain gap when the memory is inserted into the memory slot; The gold finger technology of the memory stick is poor, and the surface of the gold finger is poor. Over time, the oxide layer on the surface of the golden finger gradually thickens, leading to poor memory contact; The quality of the memory card is poor, and the contact between the reed and the gold finger of the memory card is not real.
Solution: Open the chassis, carefully wipe the gold fingers of the memory stick with rubber, remove and plug the memory stick back in, and fill the gaps on both sides of the memory stick with hot melt adhesive to prevent further oxidation during use. Note: When unplugging the memory module, be sure to unplug the power cord of the host to prevent accidental memory burning.
Example 2: The motherboard does not start, and there is no display when it is started, and there is a video card alarm sound (one is long and the other is short).
Cause of failure: Generally, the graphics card is loose or damaged.
Solution: Open the chassis and plug in the graphics card. Check the AGP slot for small foreign objects, otherwise the graphics card will not be inserted in place; For the motherboard using voice alarm, carefully identify the content of voice prompt, and then solve the corresponding fault according to the content.
If you report to the police after handling the above measures, the chip of the graphics card may be broken. Replace or repair the video card. If you hear a beep after turning on the computer, the display is normal but there is no image. The graphics card works normally when plugged into other motherboards, that is, the graphics card is incompatible with the motherboards, so the graphics card should be replaced.
Example 3: The motherboard doesn't start, it doesn't display when it starts, and there is no alarm sound.
Reasons for failure: There are many reasons, mainly the following.
Solution: Eliminate them one by one for the following reasons. You are required to be familiar with digital circuits and analog circuits, use a multimeter and sometimes use a debugging card to check faults.
(1)CPU problem
CPU without power supply: use multimeter to test three (or one) field tubes and three (or one) rectifier diodes around CPU to check whether CPU is damaged.
The CPU socket is missing or loose: this kind of fault is manifested as the point is not bright or the machine stops irregularly. You need to open the top cover on the surface of the CPU socket and carefully observe whether there are deformed pins with your eyes.
The fan fixing clamp of CPU socket is broken: other fixing methods can be considered. Generally do not replace the CPU socket, because manual welding is easy to leave hidden dangers. The CPU and radiator of SOCKET370 are fixed through the CPU socket. If the fixing spring is too tight, be careful when removing it, otherwise the plastic clip will break and there is no way to fix the CPU fan.
Error in CPU frequency set in CMOS: Clear CMOS to solve it. The jumper for clearing CMOS is generally near the lithium battery on the motherboard, and the default position is generally 1 2 short circuit. As long as it is changed to 2, 3 short circuit for a few seconds, the problem can be solved. For the old motherboard, if you can't find the jumper, just take out the battery, turn it off after the boot display enters the CMOS setting, and install the battery to discharge the CMOS.
(2) There is something wrong with the motherboard expansion slot or expansion card.
Because there is a problem with the motherboard expansion slot or expansion card, the motherboard does not respond after plugging in the expansion card such as graphics card and sound card, resulting in no display when booting. For example, the strong disassembly and assembly of AGP graphics cards leads to cracks in AGP slots, which may lead to such failures.
(3) Memory problems
Motherboards can't recognize memory, memory damage or memory mismatch: some old motherboards are very picky about memory. Once the memory that the motherboard can't recognize is plugged in, the motherboard can't start, and even some motherboards haven't given a fault prompt (beep). In addition, if different brands and types of memory are plugged in, this kind of fault sometimes occurs.
Broken pin or burned memory slot: Sometimes the reed in the memory slot will be deformed and broken due to excessive force or improper installation method, so that the memory slot will be scrapped. Note: When plugging and unplugging the memory module, use vertical force, and do not shake it from side to side. Before unplugging the memory stick, be sure to unplug the power supply of the host to prevent the memory from being charged and burning the memory stick when using the STR function. In addition, the memory should not be installed backwards, so as not to burn out the memory module after power-on. However, today's motherboards generally have a foolproof design and will not be inserted backwards.
(4) the motherboard BIOS is damaged
The BIOS of the motherboard stores important hardware data, and the BIOS is also a fragile part of the motherboard, which is easy to be damaged. Once damaged, the system will not work.
This failure is generally caused by CIH virus destroying the motherboard BIOS. Generally, after BIOS is destroyed by virus, the data in hard disk will be lost. You can judge whether the BIOS is damaged by checking whether the hard disk data is intact. When there is a debugging card, it can also be judged by whether the BIOS indicator on the card is on. When the boot block of the BIOS is not damaged, the display will not light up after booting, and the PC speaker will have a "beep" alarm sound; If the boot is damaged, the power supply and hard disk lights will be on, and the CPU fan will be turned on, but it will not start. At this time, the BIOS can only be rewritten through the programmer.
You can also plug in the ISA graphics card to see if it is displayed (if prompted, you can follow the prompts). ), if there is no boot screen, you can make a floppy disk that automatically updates the BIOS and refresh the BIOS. However, after the BIOS of some motherboards is destroyed, the floppy drive simply won't work. At this time, it is recommended to find a service provider and write the BIOS update file into the BIOS with a code writer.
(5) There is something wrong with the battery used in CMOS.
Press the power switch, the hard disk and the power light come on, and the CPU fan turns on, but the host does not start. When the battery is taken out, it can be started normally.
(6) Automatic protection and locking of the motherboard
Some motherboards have the function of automatic detection and protection. When the power supply voltage is abnormal, or the CPU is overclocked or the adjustment voltage is too high, it will automatically lock and stop working. The performance is that the motherboard does not start. At this point, CMOS can be discharged and then powered on. Some motherboards need to hold down the reset key to unlock when they are powered on.
(7) The capacitor on the motherboard is damaged.
Check the capacitor on the motherboard for bubbles or bursts. When the capacitor smokes due to high voltage or high temperature for a long time, it will bubble or drip. At this time, the capacity of the capacitor will be reduced or lost, and the capacitor will lose its filtering function, which will increase the AC component in the load current, which will lead to the unstable work of CPU, memory and related boards, easy to crash or system instability, and often lead to blue screens.
Example 4: The temperature control of the motherboard is abnormal, resulting in no display at startup.
Asus P3B-F motherboard can monitor the temperature of CPU, and a 2-minute temperature monitoring line is inserted in JTP 2Pin next to the CPU slot. Later, while playing a game, the machine suddenly turned blue. After the restart, the display screen does not light up after the self-check of the optical drive and hard disk.
Cause of failure: The temperature control cable connected to the motherboard fell off and fell on the motherboard, which led to the motherboard automatically entering the protection state and refusing to power on. Because the CPU is very hot now, many motherboards provide strict temperature monitoring and protection devices. Generally, if the CPU temperature is too high or the temperature monitoring system on the motherboard fails, the motherboard will automatically enter the protection state. Refuse to boot or alarm prompt.
Solution: Reconnect the temperature monitoring line and turn it on. Note that when your motherboard can't start normally or give an alarm, first check whether the temperature monitoring device of the motherboard is normal.
Second, CMOS class fault.
Example 5: Computers often crash, and even setting CMOS will crash.
Cause of failure: Generally, the motherboard design has poor heat dissipation or there is something wrong with the motherboard cache.
Solution: If the failure is caused by insufficient heat dissipation of the motherboard, you can touch the motherboard components around the CPU after the crash, and you will find that the temperature is very hot. After replacing the high-power fan, the crash fault can be solved.
If there is something wrong with the cache, you can enter CMOS settings and disable the cache. Of course, after the cache is disabled, the machine speed will definitely be affected. If the above methods still can't solve the problem, it is that there is something wrong with the motherboard or CPU, and it is necessary to replace the motherboard or CPU.
Example 6: CMOS parameters are lost, and after startup, it prompts "CMOS battery status is low", sometimes it can be started, and it will crash after a period of use.
Cause of failure: This phenomenon is mostly caused by insufficient CMOS power supply.
Solution: If the battery is welded, a new battery can be welded with an electric soldering iron. If it is button cell, it can be replaced directly; If it is a chip battery, you can replace this chip, preferably the same type of chip.
If the same phenomenon occurs not long after battery replacement, it is likely that the motherboard is leaking electricity. You can check whether the diode or capacitor on the motherboard is damaged, or you can use an external battery as a jumper.
Example 7: CMOS settings cannot be saved.
Cause of failure: Generally, the motherboard battery voltage is insufficient. Solution: Just replace the battery. If some motherboard batteries can't solve the problem after replacement, it is necessary to check whether there is a problem with the motherboard CMOS jumper. Sometimes, CMOS data can't be saved because the motherboard CMOS jumper is wrongly set to the clear option or set to the external battery. If it is not the above reasons, it can be judged that there is something wrong with the motherboard circuit, and it is recommended that you find a professional to repair it.
Example 8: The system cannot be installed because the motherboard antivirus is not turned off.
In the initial stage of installing Win98, a black rectangular area suddenly appeared on the screen, as if there were some hints, and then the installation stopped. Adjusting the brightness and contrast switch of the display is also invalid. Using antivirus software to kill the virus, no virus was found.
Cause of failure: This phenomenon is easy to appear on the newly bought motherboard, because by default, the antivirus settings in the BIOS of the new motherboard are mostly turned on, so similar failures will occur.
Solution: Read the motherboard instructions carefully. After entering the CMOS setup program, set the "virus warning" option in "BIOS function settings" (BIOS "enabled" is "disabled") to solve the problem.
Example 9: The mouse is not available when Windows is installed or started.
The old 586 computer, the mouse is not available when installing or starting Windows. After replacing the mouse, the fault still cannot be eliminated. It is suspected that the motherboard PS/2 mouse interface is faulty. Take it to a professional motherboard inspection point to check whether the PS/2 mouse interface is normal.
Cause of failure: IRQ setting error in CMOS parameters. This kind of fault is common in the old 586 computer, but the new motherboard generally does not have this problem.
Solution: In the power management bar of CMOS settings, there is a modem that uses IRQ items, and the options are 3, 4, 5 ... and NA. Usually, its default option is 3. If it is set to an interrupt other than 3, the fault can be eliminated.
In addition, on some old 586 computers, COM port and LPT port are connected to the outside of the chassis through signal lines. The connection of the signal line varies with the motherboard. If the connection is wrong, the mouse will not be available. Generally speaking, there are two kinds of connections:
(1) signal lines are connected with the connector in turn from 1 to 9; (2) The signal lines are cross-connected with the connection points. The upper row of the connector is respectively connected with 1, 3, 5, 7 and 9 signal lines, and the lower row is 2, 4, 6 and 8 signal lines.
Example 10: The cache on the motherboard is corrupted.
The cache on the motherboard is damaged, indicating that the running software crashed or the software could not be installed at all.
Solution: You can set the "External Cache" item to "Disabled" in CMOS settings, and then troubleshoot.
Three, I/O equipment abnormal operation failure
Example 1 1: COM port, parallel port and IDE port of motherboard are out of order.
Cause of failure: Generally, it is caused by users plugging and unplugging related hardware online.
Solution: Multi-function card can be used instead. However, before replacement, the COM port and parallel port on the motherboard must be disabled first. Note that some motherboards even have IDE ports to disable before they can be used normally.
Example 12: The keyboard interface on the motherboard cannot be used.
After the keyboard is connected, the system will crash after the prompt of "keyboard interface error" appears. Unplug the keyboard and plug it in again, and the system can start normally. After a period of use, the keyboard did not respond.
Cause of failure: Plugging and unplugging the keyboard for many times caused the keyboard interface of the motherboard to be loose.
Solution: Remove the motherboard and solder it again with an electric soldering iron. If the keyboard is plugged and unplugged with electricity and a safety resistor on the motherboard is broken (something marked with Fn on the motherboard), just change it to a resistor of 1 ohm /0.5 watt.
Example 13: The display adapter integrated on the motherboard has failed.
There is a great wall microcomputer, which rings 8 times when it is turned on. It is certain that the display card is faulty. Open the case and find that the display card is integrated on the motherboard, and there is no motherboard manual.
Cause of failure: It rang several times after booting, mostly because the motherboard memory was not inserted properly or the display card was faulty.
Solution: Look carefully at the jumper marks on the motherboard to shield the integrated display devices on the motherboard. Some motherboards need CMOS settings to prohibit the integrated graphics card on the motherboard; Then insert the good graphics card into the expansion slot.
Example 14: The parallel port of the printer on the motherboard is damaged.
The parallel ports of computers and printers above 486 are mostly integrated on the motherboard, which is prone to this kind of fault and cannot be printed.
Cause of failure: plugging and unplugging the printer signal line with electricity is most likely to damage the parallel port on the motherboard.
Solution: Check whether the printer supports DOS printing. In the pure DOS state, use DIR >；; PRN (only valid for stylus printers and some laser and inkjet printers) checks whether the printing is normal; Check the motherboard manual, set the "shield" the parallel port function on the motherboard through the jumper related to "prohibit or allow the parallel port function on the motherboard" (or set the shield through CMOS), and then add a multi-function card to the ISA expansion slot.
Example 15: The software/hard disk controller on the motherboard is damaged.
Cause of failure: Since 486, most motherboards have integrated soft/hard disk controllers, and the damage of controllers is mostly caused by hot plugging.
Solution: According to the following situations, deal with them separately.
(1) If the floppy disk controller is damaged, you can change the jumper or CMOS settings on the motherboard and add a multi-function card.
(2) The hard disk controller is broken. If the connected hard disk is less than 528MB, you can add a multi-function card. If the connected hard disk is larger than 528MB, you need to update the motherboard BIOS or use related software.
Example 16: IDE wiring error, hard disk not found.
A 40GB host, after double disk replication, reconnects the main hard disk and starts it. The machine prompts that the IDE device cannot be found, and the hard disk cannot be found to enter WinXP. After restarting the CMOS setup program, I found that I couldn't detect any IDE device, and I couldn't detect it by changing the hard disk.
Cause of failure: Such failures often occur. If the hard disk itself is not damaged, the IDE cable of the motherboard is wrongly connected or the IDE port is damaged, this kind of fault can be caused. In addition, when hanging the hard disk, if the jumper is not replaced in time, a similar situation will occur. After investigation, this example is the IDE wiring error, and the slave port of ATA/ 100 hard disk line is connected to the hard disk.
Solution: Just change to the main interface.
Fourth, power failure.
Example 17: When the power switch or reset key is damaged, it will automatically shut down after a few seconds.
Cause of failure: At present, the quality of switches and indicator lights, earphone sockets and USB sockets on many cases is too poor. If you press the reset button, it will not rebound. After power-on, because the host is always in the reset state, after pressing the power switch, the host will have no response, just like when there is no power. Therefore, the power light and hard disk light are not on, and the CPU fan does not turn.
Solution: Open the chassis and repair the power switch or reset key. The power supply on the motherboard is mostly switching power supply, and the power tubes used are independent devices. If it is damaged, just replace the power tube and capacitor.
Example 18: the power socket is loosely connected.
This situation is rare and will be restarted irregularly.
Solution: When checking, you can shake the power cord of each interface by hand in the boot state to see if there is any fault.
Example 19: fuse resistance on motherboard
Unable to find keyboard and mouse, unable to use USB mobile device.
Cause of failure: The safety resistor on the motherboard is blown.
Solution: the discrimination method is also simple, and its on-off performance is measured by the resistance of multimeter. If the safety resistor does fuse, it can be replaced by a resistor of about 0.5 ohm.
Example 20: The power supply is insufficient. The machine is equipped with nForce2 motherboard and Athlon XP 1700+ (overclocked to 2400+)CPU. Every time you turn on the computer, you always have to press the "power" button several times to light it up, and sometimes you stop checking the hard disk. A reboot usually solves the problem.
Cause of failure: The power of Athlon XP 2400+ has reached 70W, and the circuit design of nForce2 motherboard requires very high stability of power supply.
Solution: replace the famous brand high-power power supply, and the fault can be eliminated. The inferior power supply of the chassis will do great harm to the accessories of the computer. It is suggested that nForce2 motherboard players prepare a brand-name power supply of 300~350W (such as Great Wall, Buffalo, Hangjia, etc.). ).
Five, hardware compatibility failure
Example 2 1: The motherboard is not compatible with the monitor.
The computer configuration is elite P6ISA-II motherboard (i8 15E chipset) and Samsung 750S display. After installing the driver, a horizontal bar appears on the monitor when it is turned on, but it will not be displayed when it is restarted. All accessories are replaced by replacement method. It is found that P6ISA-II motherboard will fail when it is matched with Samsung 750S, but if this motherboard is matched with other monitors, the failure will not occur.
Cause of failure: The motherboard and monitor are incompatible. Solution: Replace the motherboard or monitor to solve the problem.
Example 22: The motherboard is not compatible with the graphics driver.
The computer is mainly equipped with Lenovo SX2EP motherboard (i8 15EP) and UNIKA speed matching 1500 graphics card. Installation, hard disk formatting and system installation are all normal. However, after installing the driver, the following failures occurred: the computer was shut down abnormally. After clicking "Turn off the computer" in the start menu, the shutdown screen refuses to leave the screen, and then the computer starts itself. If the graphics card driver is installed first, the shutdown is normal; After installing the motherboard driver, the computer will automatically restart when it is turned off.
Cause of failure: The motherboard is not compatible with the driver of UNIKA Speed Match 1500.
Solution: Replace the motherboard or graphics card, and the fault can be solved smoothly.
Example 23: Motherboard is incompatible with memory. This machine is nForce2 motherboard, with 256 MB of Kingmax DDR 400 (Tiny BGA package) memory added, forming a dual-channel mode with the original memory. However, after adding memory, the system becomes very unstable and will automatically restart or crash when playing games.
Cause of failure: nForce2 motherboard is very picky about memory. In addition, Kingmax memory is not compatible with many motherboards.
Solution: nForce2 motherboard works well with Kingston's DDR333(Infenion granules), DDR400 (Winbond granules) and Samsung's original memory. It is recommended to install this kind of memory.
Example 24: Motherboards and drivers are incompatible on some motherboards with miscellaneous brands. Sometimes, there will be such a phenomenon: after the motherboard driver is installed, the computer can't enter the Win98 desktop in normal mode, or the CD-ROM drive crashes slowly, and the driver can't be uninstalled under Win98.
Cause of failure: The motherboard is not compatible with the driver.
Solution: Find the latest motherboard driver and reinstall it. General problems can be solved. If not, you can reinstall the system.