BenQ R53U power power-down (0.18A) fixes one case
Symptom :
BenQ R53U power-down (not opened machine current to 0.46A ); disassemble the test after the light board, current up to 0.18A power-down.
Motherboard plate number :
Main board structure:
Physical map:
Failure Analysis:
Power-down caused by power (0.18A) , there may be short on the motherboard, or a voltage failure.
Maintenance process:
On the board by playing several voltage test points on the ground impedance and found no short circuit.
Just use the power of 2 , 3 seconds, several power measurements, as measured in the inductor is powered: 3.3V , 5V , 1.8V , 1.5V , CPU power supply 1.3V .
When measured with CPU power, the mind delighted, subconsciously find the drawings for further measurements to see a good description of the voltage signal IMVP_PWRGD are normal.
The measurement of power management chip LM27299 ‘s PIN14 is 0V , the value of play found in this diode measurement points on the ground not less. PIN12CLK_EN # for the 3V high level signal.
I think that was arbitrary CPU power supply voltage and should produce before the signal has been OK , and power management chip LM27299 is damaged, do not send the power good signal to the north and south bridge IMVP_PWRGD , has not issued to the low turn-chip clock signal. In fact, I ignored the LM27299 normally produce IMVP_PWRGD and CLK_EN # signal of the other two conditions: SYSPOK .
Repaired books, I only found LM27212 of the PDF , to find the instructions SYSPOK is to produce IMVP_PWRGD and CLK_EN # necessary conditions for these two signals. (I do not understand this graph below, it is noted, huh, huh!)
Maintenance, measured SYSPOK is low, check the map that the PU4 APL5912 the octagonal chip production.
The measurement PU4 APL5912 Pin8 , PIN6 , PIN5 conditions are met (Section 9 feet is a big belly, huh, huh), neither VCCP no SYSPOK .
Replacement, troubleshooting.
Measuring machine, play “Death Speed”!
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