Lenovo IdeaPad 15 2020 Laptop Does Not Trigger (NM-D031)

 

Laptop Model: Lenovo IdeaPad 15S IIL 2020

Motherboard number: NM-D031

Fault: Not Triggered

 

Maintenance process:

 

1. Plug it in, the current is 0.8, the charging is normal, and it does not trigger.

2. Disassemble the machine, unplug the battery, and the bare board power-on standby current is 0.02, sometimes 0.009. Press the switch to trigger normally and start the machine normally. 

The system will automatically power off after about 1 minute and cannot be triggered again. Powering off and on again can trigger booting into the system, and then powering off automatically.

　　3. I thought it was caused by high temperature. Checking the temperature is no problem, the machine is not hot. Temporarily rule out temperature issues first.

        

        4. When the automatic power-off is not triggered, test whether the standby voltage has dropped. After a test, I found that 3V is normal, 3VPG is only 2.9V, and 5V is abnormal, only 2V. Test PU1601, power supply, turn on, linear 5V, all are normal, but the output is 2V. I suspect an IC problem. I don’t have this IC in hand, so I thought of soldering it first. Wind up the gun, solder it once, and test the 5V normal output after it cools down. The system will not lose power when triggered. It's normal even after long-term testing, and it's normal even when it's turned on and off repeatedly. It's considered repaired.

Note: The solder used on this board is low temperature lead. I didn't know at first. It melted within a few seconds after the air gun blew over it.