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.

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 for repair

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 for repair

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 for repair

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.

IMG_259

Asus X540UP notebook does not start maintenance figure 4.