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Principle and maintenance process of the CPU power supply circuit
Recently a lot of friends in the Q group or Q I run FF00 test card, where to the repair, the CPU does not work, how measured, and so on, and asked much more have trouble, simply put the CPU power supply circuit principle and maintenance of processes to write about those who ask to look at the line.
Monitor point does not shine, overhaul focus the CPU power supply circuit, the CPU power supply circuit is the most fragile in the maintenance of an area, it damaged the test card display FF00. Board can be added to electricity, but the CPU does not work, because the CPU needs a stable power supply current, in order to work.
Damage to the CPU main power supply characteristics, such as the number of Internet cafes and personal users, per user can clearly see the around capacitor bulge leakage, the capacitor explosion-proof tank burst open, received such a motherboard, first drum kit the leakage capacitance replaced, the replacement value of the pressure that the capacity error of less than 20%.
FET breakdown, playing with a multimeter on the beep file can determine which FET breakdown. By measuring the interface of the ATX power, values can also be judged is 5V not 12V breakdown according to the characteristics of the capacitor to repair.
General CPU power supply circuit in all the associated circuit are set near the CPU socket. Any place will not be on the motherboard set the main power supply circuit. Voltage identification pins VID0-VID4, that is how much the voltage of the CPU requirements, how much current. Such as P3 CPU voltage slightly, P4CPU voltage is relatively low, the voltage required is the same for different frequencies of CPU, so the motherboard CPU needs much voltage necessary to tell the power management chip, power management chip after internal programming, the output CPU need the correct voltage. Phase CPU power supply voltage is to download CPU bottom view, there to teach you how to measure the CPU power supply.
Entire workflow: the main power generation circuit from the power control chip (the CPU power supply chip U1), sound effects tube (FET Q1 is from the voltage regulator role, Q2 the freewheeling regulator role), the filter capacitor ( C1 ~ CN), inductance (L1, L2), the Zener diode (D) and post-chip resistor-capacitor elements such as composition. Power controller power supply is 12V, provided directly by the yellow line, the ATX power supply. FET power supply of 5V, provided by the ATX power supply red line (P4 or above
Motherboard no-load: no load motherboard, the motherboard under the CPU is not installed according to the PS-ON button, U1 a 12V supply voltage, the control FET through the inductor and capacitor will produce a low power mains voltage or U1 does not work, then the voltage output to zero, mainly because the CPU did not provide a voltage identification signals to control the power generated by the CPU voltage. According to the different brands and different models of motherboards, this voltage is generally there are several possibilities: 0? V, 1? V, 2.0V, 5.0V. The reason is because the CPU is not installed, the voltage identification pins of the power supply controller (VID0 ~ ~ VID4) did not get the CPU over voltage identification command level signal. The internal circuit of the power supply controller chip can not work, that is I do not know when the power controller output voltage control the number of volts, while the G pole power controller not to FET output pulse control voltage, field effect tube will not work.
The motherboard in the case of no-load, the only output above several different voltage values. Even occasionally in the no-load can be measured 2.0V voltage, the voltage power is very small, because the FET is not completely work.
Motherboard plug in the CPU: When the motherboard mounted on the CPU, the CPU 5 voltage identification pins will be automatically fixed voltage identification command signal level signal to the voltage identification pins of the power supply controller, then within the power controller circuit is fully operational, then the CPU Calais voltage identification command signal, the hydrogen voltage automatically adjust the CPU working voltage required. It is the FET G output pulse control voltage, so that the two FET alternately turn, make it work in the switch state.
Works as follows: When the moment of the motherboard power, 12V, 5V, 3.3V and other voltage into the motherboard, when the voltage identification pins, the CPU 5 will provide a fixed voltage identification command to the Power Manager , power management, power and the role of the VID signal, the chip internal circuitry is fully operational.
Output high when the high-end door of the power management to the FET Q1, gate (G polar), Q1 turns on, while the lower end of the door of the power management to the field effect tube Q2 gate (G pole ) output low, Q2 closed.
Power supply Vcc 5V through Q1 adjusted by the inductor-capacitor filter add load the CPU, when the inductor L2 to generate an induced electromotive force (left positive, right negative) to stop the current increases, the inductance is this time in a storage state, the inductor filter-Chu of energy, when Q1 turns off, Q2, inductance becomes smaller in order to prevent the current will generate an induced electromotive force (left negative, right positive), charging the capacitor.
Q1 cut-off state when the internal storage of the capacitor after the after the CPU consumption after Q2 form a circuit, Q2 acts as a retention and protection of the role of this position. Often it is a specific role in the decision that it is not an easy subject to damage a component, when the inductor current or voltage increases, the most likely to burn out the FET,
the moment the arrival of a cycle, repeat the above action, so that again and again , the CPU will get a constant voltage energy. Through Q1, Q2 guide and cut-off, the inductor and capacitor filtered rectifier, resulting in a stable voltage to the CPU.
This is an overall workflow. This is the single principle of supply in a number of supply
370 motherboard interface core voltage of 1.5V and 2.5V generated each motherboard is different
, directly through the resistor in the power management chip, generally 1.5V the current is relatively large, do not use this method
, the power management chip output and control FET G and transistor B pole connected to 5V or 3.3V voltage, usually in the D pole FET or transistor C, S-pole output.
3,1.5 V and 2.5V linear module buck the general input voltage of 3.3V.
478's CPU is only one power supply CPU power to identify pin to tell the voltage of the power management chip, power management chip to control the FET, inductance, capacitance generated by the CPU voltage. 478 in the CPU needs a large current, a pair of FET can not meet the requirements, the need for four or six FET in parallel, commonly known as a number of power supply.
! Like the CPU power supply circuit, the three pairs of FET, which is a number of works, three sets of power supply, now the CPU power is up to 80 watts, the current is very large. At this time, the CPU can run stable in the high-frequency high-current, stable, it is necessary to adopt a number of supply, then this is the number of individual works in the power supply.
After having the motherboard, to overhaul the CPU power supply circuit, the same so long as individual in principle, a number of power supply maintenance principle is the same.
. Motherboard plug in the CPU, the measurements show the card is FF00, it proves that the CPU is not working, the CPU does not work, first check all the equipment working conditions - the power supply on the motherboard, in order to ensure that its work stable or working correctly, the most important issue is the source of power is the power supply necessary, followed by the clock that is the core clock beating necessary for normal, normal maintenance it's reset. : L
motherboard's Q1X pole FET X pole on can determine the power supply is normal. The multimeter in the file on the DC 20V, red table pen ground test point Q2 of the D pole of the black pen point or point Q1 X-pole; or point of the inductance coil L2 to determine whether the supply voltage.
That which is which is the Q1 Q2, the Q1D very connected to the red 5V or 12V, when the multimeter to play in the beep file, a table pen on the ATX Power the yellow SE12V inside, Another to connect Q1 D pole, the point which D pole, loud beep which is Q1 is.
When you find the Q1 is that Q2 is easy to find, when we later determine Q1, red table pen point Q1 X-pole, the black pen next to it to find and of Q2 pole which is connected to or buzzer, it can be determined the a single set of power supply to determine a power supply.
Like some of the motherboard, that it belongs to the three-phase power supply on the motherboard in a number of supply, the Lord is the parallel of a single power supply, in order to increase the current to take a parallel relationship, the majority of the motherboard power supply circuit uses two circuits. or more, forced to meet the needs of a CPU power, the power to 80 watts, the operating current of 50A.
A number of supply not only to provide adequate and reliable power for the CPU, but also through the shunt to the load of each FET reduced to create a good working environment for the stable operation of the motherboard, the three power supply circuit with a specific operating mode of the Intel Corporation.
How to find the power management chip in the CPU power supply circuit? Just make sure a power supply with a multimeter to play in the beep file, a table pen connected to differential FET Q1 CONTROL (G polar) Another table pen and the next chip to connect later to connectivity know that it is not a power management chip. Find the power management chip, and do not have to find the voltage identification pins.
How to overhaul the CPU supply road:
a measure of Q1 D very 5V or 12V, is provided directly by the red 5V ATX power or yellow SE12V,. If you do not check the power supply red line or yellow SE line to the D pole. If normal, the next step.
2, measured Q1 G pole 3 ~ 5V control voltage from the power management chip, and if normal, bad FET, the replacement of the FET. If it is not normal, Q1, G very vacant, the output voltage measured power chip.
3, the measured power chip output voltage, if not output, check the power chip power supply 12V or 5V, provided by the ATX power supply, no electricity, check the relevant line. If the power supply, change the power chip.
4, the measured PG good power source 5V (power gray line), if normal-for-power chip, if not normal, replace the chip connected to the gray line and power.
Note: often bad power supply control chip and FET and R1 limit the transition resistance, the possibility of bad general CPU power supply 15V main power supply will have no output, power control chips, if you have a base in an output is not normal, is the output of the FET bad most (such as Q3 1.5V output). .
Generally have a situation in 1.5,2.5 V main power supply, generally in Q1 or Q2, D1, more damage. 2.5V main supply 1.5V no, 80% of control 1.5V output FET damage; if not 2.5V output, same repair 1.5V; If 1.5V, 2.5 V main power supply at the same time, when the normal supply of electricity and power chip (12V, 5V), 80% of the chip is broken.
As the main power supply circuit in a number of parallel relationship, each individual power supply, single FET damage will lead to instability of the CPU power supply circuit. Want to overhaul not blind fold to see the FET in the power supply circuit, open circuit method available to get rid of the first FET to disconnect a group, and then to determine the maintenance of their good or bad this is the CPU main power supply circuit process. This is the repair process of the CPU power supply circuit.
The CPU does not work, the test card ran only 00, the CF and C0, the FF and so on. Went to the C1,
but some friends asked why the CPU power supply, why the test card to run FF or 00, why the CPU work? This may according to our rules of maintenance of the pre-supply, and then repair the clock to repair bit.
Even if you CPU power supply is normal, but the clock is not normal or abnormal reset, can lead to CPU
South bridge no power supply, power supply is high or low, will cause the CPU does not work.
North bridge power supply, power supply, high or low imitation will cause the CPU does not work.
South bridge, North bridge Weld, bad, will cause the CPU is not working
memory, not the power supply will cause the CPU does not work (for the board).
Data lines of the CPU socket, if there is a north bridge and open or short circuit will cause the CPU does not work. Best to have a CPU lamp holders, onto the CPU socket, a power, you know which data line is open, short, and so on, than you to a root of the CPU data lines.
CPU frequency jumper does not, will not work. BIOS bad CPU will not work for the CPU does not work.
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