Lenovo X270 laptop Won't Turn On repair

Lenovo X270 laptop Won’t Turn On repair

Machine model: Lenovo X270

Board number: NM-B061

Symptom: Laptop Won’t Turn On, occasional standby 0.013.

Lenovo X270 Laptop Won’t Turn On Repair Figure 1.

Lenovo X270 Laptop Won’t Turn On Repair Figure 2.

Maintenance process:Connect the power supply measures the current detection resistance of the charging chip to be 19V, which is isolated by Current protection, the common point is 9.2V, and sometimes there is no 3V5V, just plug it in and unplug it. It is measured that the 3V Inductor is 3.3V normally, and the 5V Inductor is abnormally 4.3V.

Lenovo X270 Laptop Won’t Turn On Repair Figure 3.

Thinking of FB FB, 5V is divided by 150K and 100K resistors to 2V. At this time, the measurement of 2V is correct, but it feels a bit strange to divide 4.3 to 2V. After measuring the two resistors, the diode value is 0.000, remove it One pin of one resistor, two resistors are measured at 100K respectively, doesn’t the resistor just get bigger when it’s bad, why is it getting smaller?

Lenovo X270 Laptop Won’t Turn On Repair Figure 4.

Lenovo X270 Laptop Won’t Turn On Repair Figure 5.

The resistance is 0201, it is too difficult to find the same, you can only scratch a scrape solder joint on the 0402, replace the resistance plug-in automatic power-up, 5V VCC recovery 4.98V, current cheerful current of change, connect the screen booting up.