HOW TO REPAIR COMPUTER MOTHERBOARD

MOTHERBOARD NOT BOOT
a. check whether the short circuit CPU voltage
b. MOS tube 5V and 3V voltage is normal
c. check motherboard VID0-VID5 signal
d. 12V Power Management Chip 0 ohm affect, MOS capacitor for the wrong side of the tube will affect the voltage
e. VID_GOOD signal
2. No clock
a first check the clock chip 2.5V and 3.3V power supply is normal
b 14.318MHZ whether the starting crystal oscillator, capacitor bad or adverse affect body vibration can not afford to
c check the clock chip VTT_PWRGD (intel chipset)
3-d clock chip resistor
e bad body clock chip
DIMM on the clock:
A check whether the output clock frequency chips to North Bridge
Check the power supply 2 DIMM and 2 .. 5V 1.25V is normal (next to the reference voltage 1.25V Northbridge is normal)
3. DIMM clock chip is bad
4 North Bridge to the clock chip 22 ohm is normal
5. Northbridge poor body
3. CPU reset signal
a. check whether the normal voltage and frequency. (DIMM easily under a bad transistor)
b. clock chip resistance, exclusion is normal
c. North Bridge to the DIMM frequency output is normal. (INTEL. VIA. SIS chipset, the aforesaid signal line is working
d. North Bridge to the CPU signal lines AD Block
e. SIS PCI board investigation of FRAME # and DEVSEL # signal, if the normal two signals can be ruled out BIOS and
W83697 possible, the network will also affect the North Bridge chip and
f. NVIDIA's board BIOS and W83697 will affect not reset
g. North Bridge Ontology bad (NVIDIA and the SIS board, BIOS will not affect the CPU reset)
4. The whole board without reset
a check whether basic supply voltage and frequency of normal
b check whether the output reset signal to the Southbridge MS_5T 2 feet (3V reset voltage)
c check MS-5 3.4.5-pin voltage is normal, with or without short-circuit
d South Bridge is poor body
e check switch on the FP-RST signal is connected to a 3V voltage general MS-5, clock, network chips, MS-3
f check MS-5 in the POWER GOOD 42 feet and PWR-OK 46-pin signal is normal
g check MS-7 in the first 4 feet and 7 feet POWERGOOD signals whether the output signal 4 into POWERGOOD 7
Out
h check VCC2.5V and whether the short-circuit short-circuit the Northbridge 1.25V bad

5 reset does not boot
a. clock. reset. Southbridge voltage is normal
b. Charles PW-OK, and PWR-GOOD signal is normal
c. TTL circuits and related components, check whether the abnormal
d. check the AD PCI signal and control signal to the South Bridge
e. South Bridge poor body
f. South Bridge side of the frequency of the crystal 32.768K less will affect the reset does not open, will also affect the COM port test, but
g. MS-3 is normal
h. NVIDIA chipset, BIOS is bad
7 Delay start
a. clock frequency, voltage is normal
b. clock chip side of the resistance, exclusion, with or without frequency output
c. TTL circuits and MS-5, MS-7 is related to the normal line
d. network chip voltage is normal or poor body
e. BIOS to the South Bridge, the signal is normal
8 reset Boot
a. check whether the bad BIOS information
b. check reset, whether the low frequency
c. check FP-RST signal and related components are normal
d. PCI lines are normal to the South Bridge
e. South Bridge Ontology bad run DD
a. check PCI bus
b. check BIOS Bus
c. check CPU bus
d. BIOS poor body
e. I / O chip
f. Clock Chip
g. MS-3
h. South Bridge run D3
a. Clear CMOS
b. update BIOS information
c. whether the connection is bad memory
d. motherboard memory power supply is normal DIMM3.3V, DDR2.5V 1.25V
e. check the memory frequency
f. check MS.MD.RAS.CAS
g. check the AD CPU signal. control line

h. check 74F244.74F245 buffer board 370
i. check I / O chip
j. check the memory to the North Bridge of the signal line, the memory on the 91 and 92 feet of potential signal 3V, through live I / O clock, Southbridge best Huabu Kai machine
a. check CMOS settings are consistent with the CPU itself, the frequency
b. check CPU multiplier signal (4 signals directly to the South Bridge)
c. check the voltage settings are normal
d. check CPU's control signals]
e. check clock chip power supply. output frequency is normal
f. check MS-3 (next to the power transistor, the voltage down)
Short-circuit board
1. Observation
2. Touch method
3. Exclusion
4. From small range to large-scale
5. A signal line North Bridge voltage 5V, 3.3V, 2.5V, 1.8V, DDR-VTT, VCORE, VCC-AGP, VTT-VID
South Bridge Voltage 3.3V, 25V, 1.8V, 1.5V, 3VSB
I / O 5V, 3.3V, 5VSB
BIOS 3.3V, 5V
Audio chip 3.3V, 5V 8738 is 5V
Network chip 3.3V, 3VSB
Power management chip 12V, 5V, VCORE
Clock 3.3V, 2.5V
75,232 plus or minus 12V, 5V
South Bridge PCI on 14PIN have 3VSB
For the short-circuit boards to repair
a search of all AD board signal lines, including (CPU Block, PCI, DIMM, ISA)
b. other control signals and clock chip, the clock chip output pin, all the I / O interface signals and diodes are normal (resistance)
CPU voltage anomalies to maintenance
a. first check CPU voltage, power management ICs and MOS tube a short circuit and burn out phenomenon
b. check the signal is normal VID0-VID5