The screen gets dimmer when AC adapter is plugged into laptop

Problem description:

The screen gets dimmer when AC adapter is plugged into the laptop. The screen is bright when laptop runs on the battery power.

Possible cause:

LCD brightness settings in the power management software or BIOS setup menu.

Possible troubleshooting steps and repair solution:

Most likely this problem is related to the LCD brightness settings in the power management software or BIOS setup menu.

1. Connect your laptop to the AC adapter. Try increasing LCD screen brightness through a shortcut on the keyboard.
For Toshiba laptops hold down the Fn key and press on F6/F7 keys to increase/decrease the brightness.
For Dell laptops hold down the Fn key and use Up/Down arrow keys.
For IBM laptops hold down the Fn key and use Home/End keys.
For HP laptop hold down the Fn key and use F7/F8 keys.

Some other brands may have different keyboard shortcuts for increasing/decreasing LCD screen brightness.

2. In some brands you can adjust screen brightness in the BIOS setup menu. Enter the BIOS and make sure the brightness is set to 100% for AC mode.Correct settings if needed.

3. Check setting in the power management software installed on your laptop. Make sure the screen brightness is set to 100% for AC mode. Correct settings if needed.