1. AC power adapter failure.
2. DC power jack failure.
Possible troubleshooting steps and repair solution:
First of all, test the AC power adapter. It’s possible that the power cord on the AC adapter is damaged. When the cord is moved, power stops coming from the adapter to the laptop and it starts running from the battery. In most cases, the damage occurs in the area where the cord is connected to the power plug.
You have a couple of options here:
1. Test your AC adapter with a voltmeter. Make sure the power is not cutting off when you move the power cord.
2. Test your laptop with another known good AC adapter.
If you still experiencing the same problem with a new AC power adapter, most likely your problem is related to the power jack inside the laptop. The power jack is a socket where you plug the adapter.
It’s necessary to remove the motherboard and take a closer look at the power jack.
1. Resolder the power jack if it’s not making good contact with the motherboard.
2. Replace the power jack if it’s broken.