Backlight only works when laptop is NOT plugged in and charging

[sportstar583]

For some reason, my backlight for my Inspiron 1720 laptop only works when my laptop is not plugged in and charging. I know this because the screen become noticeably dimmer when I plug in the charger and when I unplug the charger, the screen goes back to where I don't have to squint to read. I've googled this problem and couldn't find anything. Please help!

 

[carnageX]

Have you checked the power settings to see if the screen brightness is turned down when it gets plugged in on AC power?

 

[sportstar583]

Yes I have. It's not the brightness. I'm 100% sure it's the backlight because the brightness setting for plugged in and not plugged in are the EXACT same.

 

[Harper]

Motherboard is faulty. I have seen this problem before.

 

[sportstar583]

Any ways to fix it?

 

[Harper]

Replace motherboard. However how other motherboard prices of laptop are not cheap.