Asus X540UP notebook does not start for repair

The notebook is not turned on, and you see a broken line after running, but you have to remove the capacitor to make it up. Direct flying line, power-on test, perfect lighting machine.

Machine model: ASUS X540UP notebook

Fault symptom: the notebook does not turn on.

Maintenance process:

An ASUS X540UP notebook, the fault is that the notebook does not turn on.

Power-on detection standby has 3V and 5V, and the point switch is not triggered. It was found that 3VSUS_PWRGD was lowered, only about 0.4V.

Asus X540UP notebook does not start maintenance figure 1.

Check the bitmap display and connect to these places. When removed to D5804, 3VSUS_PWRGD recovered to 3.3V

Asus X540UP notebook does not start maintenance figure 2.

It is known that the high level of 1.0VSUS_PWRGD should be set first, so that 3VSUS_PWRGD will not be pulled low. Tracing from PU8302, 12 pins are normal at 5V, and 8 pins are normal at EN3.3V TOP 0V of 9 pins is abnormal, replace the 620K resistor with the same 0V, and trace the pull-up of 19V without voltage.

Asus X540UP notebook does not start maintenance figure 3.

After running the line, I saw a broken line, but I had to remove the capacitor to make it up. Direct flying line, power-on test, perfect lighting machine.