Motherboard failure and Maintenance Basics

A key component of the motherboard is the computer used to connect a variety of computer equipment, the computer plays a vital role. If the board fails, your computer can not properly used. At present more and more integrated motherboard, motherboard repair has become increasingly difficult, often using specialized digital testing equipment to complete, but the control board and comprehensive maintenance technology, the rapid failure investigation board is still very necessary.

1, causing the main board failure

Today, the integrated motherboard components and circuitry are many and complex reasons for the resulting failure is also relatively high. Common board failures caused by many environmental bad, but because of quality problems caused by the motherboard's own failure also relatively more, while some of the problems are caused by human users.

1, motherboard adverse operating environment

If the board covered with dust, can cause short-circuit and other signal failure. If the power supply is damaged, or the power grid voltage transient spikes generated pulses will cause the motherboard chip near the power supply plug is damaged, causing the motherboard failure; In addition, often caused by static electricity on the motherboard chipset (especially CMOS chip) is the breakdown, causing failures .

2, the motherboard itself, quality issues

As the chip on the motherboard and other components of poor quality, the use of aging over time will damage the device, leading to the motherboard failure.

3, human error

Hot-swappable hardware is very dangerous, and many motherboard failures are caused by hot, the most common is the burning of the keyboard, mouse port, a serious motherboard will be burned. Charged pluggable I / O card, board and plug in installed when the force improperly, can result in interfaces, chips damage.

2, motherboard repair method commonly used in

Motherboard fault identification, usually through the progressive removal or replacement of the motherboard is connected to the board, first rule out the possible problems of these components, you can target lock on the motherboard. The actual maintenance, frequently used repair methods listed below.

1, observation

Check for foreign objects falling into the motherboard between the components. If the dismantling chassis, the conductive material accidentally fall into the motherboard components stuck in between, it could lead to "protection fault." In addition, check the motherboard and the chassis backplane installed between it and a small board for the support of small copper pillars; whether the motherboard installed improperly, or chassis deformation, leaving the motherboard in direct contact with the chassis, so that short-circuit protection with automatic power cut off power supply.
Check the motherboard battery: If the computer does not boot correctly to find the hard disk, system time is incorrect after boot, CMOS settings can not be saved, it can first check the motherboard CMOS jumper, the jumper changed to "NORMAL" option (typically 1-2 ) and then re-set. CMOS jumper if it is not wrong, it is likely because the motherboard is damaged or the battery voltage of the battery shortage caused, please try from another motherboard battery.
Check the motherboard Northbridge chipset cooling effect: some brand-name motherboard heatsink on the Northbridge chip, dispense, and this may result in chip cooling ineffective, resulting in system operation some time after the crash. Encountered such a situation, self-made heat sink can be installed, or add a cooling effect of a good chassis fan.
Check the motherboard capacitors: aluminum electrolytic capacitors on the motherboard (usually around the CPU socket) internal use of the electrolyte, due to time, temperature, quality and other reasons, make it happen "aging" phenomenon, which will lead to anti-motherboard interfere with the decline in the impact indicators of machine work properly. We can buy with the "aging" the same size capacitor, ready for electric iron, solder wire, rosin, will be "aging" can be replaced.
Double-check all the motherboard plugs, sockets is skew, resistance, capacitance pin is touching the surface is scorched, the chip surface is cracking, copper foil is blown on the motherboard; touch the surface of some chips, if the abnormal burning can for a chip to try; encountered areas of doubt, with the amount of about multimeter.

2, dust France

The larger board is gathering dust and more places. Dust can easily lead to poor contact socket and the board In addition, a number of add-in cards on the motherboard, chip pin form, often because of poor contact pin-oxidation.
Proposed to use wool brush to gently brush the dust on the motherboard must be careful not to force too much or move too fast in order to avoid the surface patches Pengdiao motherboard components or loosening of components, which result in cold solder joint. Note clear CPU slot is used to detect CPU temperature, or the motherboard inside the chassis used to monitor the temperature of the dust on the thermal resistance, otherwise it will cause the motherboard to the temperature of recognition errors, which lead to board fault protection. If it is oxidation caused by poor contact pin socket, you can have the hardness of folded white paper (smooth surface, and that for the outside), insert the tank back and forth polished; for the card pins can be used an eraser to the surface oxide layer, and then re - plug.

3, check whether there are short-circuit motherboard

In what should be measured prior to power on the motherboard whether there is short circuit, to avoid accidents. Judging methods are: measuring the power chip resistor between the pin and the ground. The power plug is not inserted, the resistance should normally be to 300Ω, the minimum should not be less than 100Ω. Test-retest about reverse resistance values, slightly different, but not too much difference. If the positive and negative or close to the resistance of a small turn-on, it shows a short circuit occurs the motherboard.
Motherboard short circuit reason may be that the motherboard is damaged, the resistors and capacitors, or have conductive debris, it could be the motherboard being the breakdown of the chip. To find out the breakdown of the chip, you can power-measurement of the power plug. Generally measured power supply +5 V and +12 V. When they find out too much of a voltage deviation from the standard, you can cut through the separation or some lead, or unplug some chips test-retest voltage. When cut a certain wire or unplug a piece of silicon, if the voltage becomes normal, then this leads to the component lead or pull down the chip, that is, failures.

4, plug exchange

This method can determine the failure is on the motherboard, or in the I / O device? That is, the same type plug-in board, or chip exchange, and then the changes in the phenomenon of failure to determine failures. It is mainly used for easy plug maintenance environment, such as memory, self-test error, exchangeable same memory chip or memory to determine the cause of troubles.
To do so: First off, and then pull out the plug-in board-by-block; each pulled out a sheet on the observation of the machine start running, once pulled out a piece, the board is running normally, then the plug-in board is faulty, or the corresponding I / O bus slots and the load circuit fault; if it pulled out all the plug-in boards, the system not boot normally, then the fault is likely on the motherboard.

5, static / dynamic measurement method

Static measurement: Let the board be suspended in a close-up mode, according to the logical principle of the circuit or chip output and input of the logical relationship between the use multimeter or logic level pen measuring the relevant points to analyze and judge the cause of troubles.
Dynamic Measurement and Analysis of Law: the preparation of specific procedures or artificial assertion normal conditions, the machine is running, measured with the oscilloscope to observe the waveform components, and compared with the normal waveform in order to determine fault location.
As the control logic on the motherboard increasingly integrated, so its logical correctness, has become very difficult to determine by measuring. Recommend that you first determine the relationship between the logic chip and a simple resistance-capacitance components, and then focused on the logical relationship failure is hard to determine the large-scale integrated circuit chips.

6, program testing method

The Act is mainly used for checking a variety of interface circuits, as well as a variety of circuit parameters with the address whether there is fault, its principle is to use the software to send data, commands, through reading the line status, and a chip (such as the register) state, to identify the fault site.
To use this method, your CPU and the bus must be running normally, be able to run the diagnostic software that can run the installation on the I / O bus slots on the diagnosis of cards. You can use the random diagnostic procedures, special maintenance diagnostics card, or on the basis of technical parameters (such as interface address), specific diagnostic procedures to support self-compiled hardware maintenance. However, you write the diagnostic procedures to be strict, comprehensive and focused, enabling emergence of certain key parts of a regular signal, able to carry out repeated tests occasional failure, it will show an error of record.