Lenovo Xiaoxinchao 7000-13 notebook does not start repair

Machine model: Lenovo Xiaoxinchao 7000-13 notebook

Fault symptom: the notebook does not turn on.

Maintenance process:

Lenovo Xiaoxinchao 7000-13, plug-in adjustable power-on does not trigger no standby. Remove the back cover, unplug the COMS battery and turn it on again after a while. The fault remains.

Measure the inductance of the whole motherboard, and there is no obvious short circuit. After power-on measurement, it is found that there is still no 3V5V. Looking for the drawings, it is found that the protective isolation tube of this machine is N tube, and the physical measurement is found on the board.

The notebook on Lenovo Xiaoxinchao 7000-13 is not turned on for maintenance. Figure 1

Look for it according to the bitmap.

The notebook on Lenovo Xiaoxinchao 7000-13 is not turned on for maintenance. Figure 2

Lenovo Xiaoxinchao 7000-13 Notebook Maintenance without Booting Figure 3

Find out that the physical measurement is normal, and the first tube is not completely connected. Check which chip controls the G pole of the isolation protection tube. Continue to trace that there is no voltage at one pin of the charging chip, and measure that the resistance is normal, the capacitance is normal, the diode is wrong, and the positive and negative are 580.

The notebook on Lenovo Xiaoxinchao 7000-13 is not turned on for maintenance. Figure 4

Replace D5901, and the plug-in current comes out, but the adjustable power supply and current light are still short.

The notebook on Lenovo Xiaoxinchao 7000-13 is not turned on for maintenance. Figure 5

It is found that the inductance of the whole board is still normal and there is no obvious short circuit. On the forum to learn experience, some people say that the screen interface is short-circuited.