Maintenance of ASUS x540up notebook no booting

Power-on detection standby is 3V 5V, and the point switch is not triggered. Upon inspection, it is found that 3VSUS_PWRGD is pulled low, and the high level of 1.0VSUS_PWRGD is required first, so that 3VSUS_PWRGD will not be pulled low. After running the line, it is found that there is a disconnection, but the capacitor must be removed to make up for it. Direct flying line, power-on test, perfect lighting machine.

Machine model: ASUS x540up notebook

Fault phenomenon: notebook no booting

Maintenance process:

A ASUS x540up laptop, the fault is the notebook no booting.
Power on detection standby is 3V 5V, click Switch no power on.After inspection, 3vsus was found_Pwrgd was lowered to 0.4V or so.

Maintenance of ASUS x540up notebook no booting
Maintenance drawing 1 of ASUS x540up notebook no booting

Check Boardview, connect to these places.When removed to d5804, 3vsus_Pwrgd recovered to 3.3V.

Maintenance of ASUS x540up notebook no booting
Maintenance drawing 2 of ASUS x540up notebook no booting

It is known that 1.0 vsus is needed first_High level of pwrgd, 3vsus_Pwrgd doesn’t pull down.Trace from pu8302, 12 pin 5V normal, 8 pin en3.3v normal.9 pin top 0V is abnormal. Replace the 620k resistor as 0V, and trace the pull-up 19v without voltage.

Maintenance of ASUS x540up notebook no booting
ASUS x540up notebook no booting maintenance Figure 3

After running the line, we can see that there is a broken line, but we need to remove the auto power off capacity to make up.Direct Jump wire, power on test,Normally booting up.

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no booting ance drawing of ASUS c340x58014