Asus U303L notebook does not show maintenance when it is turned on

Asus U303L notebook does not show maintenance when it is turned on.

It was suspected that the resistor was leaking. The R2014 resistor was tested by 10K and 100K in turn. The voltage of HDP was different, which ruled out the problem of CPU. It was caused by the leakage of R4521 resistor. Remove the motherboard, wash R2014 with washing water, and the boot is normal.

Machine model: ASUS U303L notebook

Malfunction: The notebook does not display when it is turned on.

Maintenance process:

An ASUS U303L notebook, the fault description notebook does not display when it is turned on, and the case is responsive. You can’t change the screen test. It’s normal to put the screen on another machine for testing.

The measuring screen is powered by 3.3V, and it only drops when it comes out during the power-on test screen, so as to eliminate the power supply problem.

Check that there is signal HPD on the screen, and the oscilloscope tests that it is about 0.8V at the moment of power-on, which is obviously abnormal. Unplug the screen line to measure the ground secondary body value, positive and negative 320. Looking at the point bitmap, this signal goes directly to the CPU through a node. The pull-up resistor R2014 is not installed, and there is a 100K ground drain resistor R4521 on the back.