What Would Cause a Laptop Screen to Go Dim?

A dim laptop LCD can make it hard to see and get your work done, costing your business precious time and money. Best case scenario, this is simply due to a loose adapter cord or incorrect power settings. Worst case scenario, the laptop's LCD screen is failing and needs replaced.

The easiest explanation for a suddenly dim laptop screen is a loose AC adapter cord. Most laptops automatically dim the screen brightness when they run on battery to minimize power usage. Check that the AC cord is firmly connected to the outlet and laptop. There should be no movement at the laptop connection -- if there is, the power component inside may be damaged and require repair. Verify that the outlet is live by plugging in a different device, such as a lamp or radio. If the outlet works and all connections are solid, your adapter may have failed and needs replacement.

Laptops allow you to control the brightness of your screen, which helps give a better picture, reduce eyestrain or save electricity while on battery power. Adjusting this setting incorrectly can cause an unusually dim screen. The controls for display brightness are usually found under Start, Control Panel and System and Security. Click Power Options to open a new dialog and find the Screen Brightness control. There should be separate controls for when the laptop is on AC power or battery power. Adjust these as desired to correct screen brightness.

One of the more complicated causes of a dim laptop screen is failure of the LCD itself. Behind that liquid crystal display, an inverter board and backlight bulb control the picture. The inverter board converts the low voltage your laptop's innards uses into the higher voltage required by the long bulb that lights up the LCD screen. If the inverter board or bulb fail, you're left with a very dim image on the screen. Generally speaking, the entire screen needs replacing when one of these two components fail, although some service shops may be able to replace just the bulb.

Checking your adapter simply requires some experimenting, as you wiggle, plug and unplug the cord to check for problems. Check the status bar at the bottom of the desktop screen to see if your laptop is running on AC power or battery while your cord is plugged into a working outlet. If it's showing battery power even though all connections are correct, the laptop isn't receiving power through the adapter, due to cord failure or a broken power connector inside the machine. A quick way to tell if your laptop's brightness controls are off is to use the F keys at the top of the keyboard to brighten the screen. Press the brightness up control -- which usually looks like a little sun with an up arrow on your F keys -- while holding the FN key, and you should brighten the screen. If it does, this means your settings are off. Bad components require an external monitor to double check, as a perfect image on another monitor but dim laptop screen points to LCD failure.