Motherboard leakage How to do

The motherboard leakage Solution method:

In general, the motherboard is now a bad power supply heart slice is very likely, the power supply heart piece is broken, the CPU generally no temperature, at this time you can use digital multimeter diode gear measuring inductance and ground, if the multimeter is called a long word, power supply heart is good, if the inductor to the ground short-circuit, the motherboard power part of the problem, First of the motherboard on a number of regulating power transistor to take down, if the inductance or short circuit, the motherboard power supply heart piece is absolutely broken! and adjust the power of the transistor is bad, the transistor next to the capacitor is generally bad (the motherboard capacitance quality detection that is too simple, only to see the line, the capacitor is broken, Absolute capacitance in the middle will definitely take a small part of it.

First of all, I do not like some way to say that the current will know that the IC, capacitance, inductance or resistance leakage short-circuit, but so far there is no I can not find leakage.

And the leakage is divided into three kinds of situation, each has its own methods:

1, small current leakage, regardless of size, the above electrical power supply does not protect whichever. Leakage current in more than 100MA, usually have obvious fever, we can go to touch, find the heating element. If the heat is not too obvious, can be appropriate to improve the voltage, but for the sake of safety voltage should be controlled within 8V, the current to no more than 200MA appropriate; If the leakage current is too small, the voltage high to 8V still no obvious fever, it can only remove power and CPU, if necessary, even when the Continue to increase the voltage to the current up to 200MA, you can easily find the heating element. Here are three points to note:

(1) Why should the CPU be removed? Remove power and amplifier good understanding, high voltage is easy to damage, but the CPU is powered by power supply, the power has taken it will be bad? The answer is yes, the various CPUs are not as simple as we think, some things are not published, we do not know, to MTK, for example, In the case of normal power to remove the CPU and then press the boot key at this time there is no current, this is enough to indicate that the CPU and power supply has a direct relationship, and then you can try not to take the CPU plus voltage to see if it will be bad, this I have learned.

(2) The heating element is not necessarily a faulty component. For example, a power supply IC to the load power supply, such as load short-circuit is usually the most important power supply IC, in this case we can use the substitution method and open circuit method to find the real point of failure.

(3) Sometimes add voltage when the current does not rise back down, to normal voltage when the leakage has been a lot smaller. That is better than a little try, often back to normal voltage when there is no leakage, this and that "burning machine Dafa" a bit similar yo.

2, large current leakage, that is, the power supply on the protection. This situation we should first measure the leakage resistance (i.e. both positive and negative resistance) if the resistance is not 0, even if only a few euro, we can also use the hand-touch method to find short circuit components. But at this point to the power supply voltage to 0, add electricity, and then slowly raise the voltage, when the current up to 200MA to find a hot spot is very easy. You can totally see it burning smoke, looking for smoke components on the line!

3, a direct short-circuit, this can not be touched by hand. Direct short circuit (such as welding point short circuit) at this time its resistance is 0, the current will not be too big fever, we can only use open circuit cutting method to exclude. That is, one to remove the possible components to try (if you know how to disconnect this component from the B + connection without taking down will be more convenient), the most likely is the MP3 amplifier IC, followed by power and amplifier. Of course, circuit maintenance experts will have more ways to find it, this is not discussed here.

The last thing to add is: Some models (such as some M-machine) with the power supply itself will have leakage, this is not properly connected to the battery type line caused, we have to determine whether it has leakage can be such wiring: from the battery contact point out the positive and negative, and then put the battery cathode affixed to a piece of paper, loaded into the battery, Then use the power supply through the positive and negative poles to the phone to power, it is clear

Additional motherboard common Failure analysis:

Common fault One: no display on the boot

Computer boot no display, the first thing to check is the BIOS. Important hardware data is stored in the BIOS of the motherboard. At the same time, the BIOS is also a more vulnerable part of the motherboard, very vulnerable to damage, once the damage will cause the system can not run, such failures are generally due to the motherboard BIOS is CIH virus damage caused by the general BIOS after the virus destroyed the hard drive data will be lost , so you can detect if the hard disk data is intact to determine whether the BIOS is damaged, if the hard disk data intact, then there are three reasons for the boot does not show the phenomenon:

1, because the motherboard expansion slot or expansion card problems, resulting in plugging such as sound card and other expansion cards after the motherboard does not respond without display.

2, jumper board in the CMOS set CPU frequency is not correct, it may also cause the failure to display, as long as the elimination of CMOS can be resolved. Clear the CMOS jumper is typically near the lithium battery on the motherboard, its default position is generally 1, 2 short circuit, as long as it is changed to 2, 3 short-circuit a few seconds to solve the problem, for the old motherboard if the user can not find the jumper, as long as the battery off, to boot display into the CMOS settings after the shutdown, The battery is also up to the purpose of the CMOS discharge.

3, the motherboard does not recognize memory, memory corruption or memory mismatch will also lead to the failure of the boot display. Some old motherboards are more critical of memory, and once plugged into the motherboard can not recognize the memory, the motherboard will not be able to start, and even some motherboards do not give you any fault prompts (tweet). Of course, sometimes in order to expand the memory to improve the performance of the system, the result of inserting different brands, types of memory will also lead to the emergence of such failures, so in the overhaul, should pay more attention to.

For failure of the motherboard BIOS to be compromised, can plug in the ISA video card to see if there is no boot screen, you can make an automatic Update BIOS floppy disk, refresh the BIOS, but some motherboard bios is damaged, the floppy drive does not work at this time, you can try to use hot plug method to solve. However, the use of hot-plug extraction requires the same BIOS may also cause some components of the motherboard damage, so the reliable method is to use the write code to write the BIOS update files inside the BIOS, you can find a computer to solve this service is more secure.

Common fault Two: CMOS settings cannot be saved

This type of failure is generally due to the motherboard battery voltage is not caused by the replacement can be, but some of the motherboard battery replacement can not solve the problem, at this time there are two possible:

1, the motherboard circuit problems, to find professional maintenance;

2, the motherboard CMOS jumper problem, sometimes because of the wrong motherboard on the CMOS jumper set to clear options, or set into an external battery, so that the CMOS data can not be saved.