How to Test an LCD Inverter

By Darla Ferrara

An inverter is an electrical device on the bottom of your laptop screen. The job of the inverter is to convert DC electrical current to AC voltage to maintain power to the backlight lamp. If the display on your laptop is dark but working, odds are the inverter or the lamp are at fault. When troubleshooting monitor problems on a laptop, you may need to evaluate the inverter to determine which of the two parts is malfunctioning.

Things You'll Need

  • Phillips screwdriver
  • Multimeter
  • Working back light lamp

Step 1

Remove the screen bezel on your laptop. The bezel is the piece of the computer casing that surrounds and protects the LCD screen. To remove the bezel, remove the screws around the screen. Bezel removal method may vary by model. Once the screws come out, the bezel should pop off. The inverter will be under the screen.

Step 2

Attach the positive probe (+) of a multimeter to the pin 1 on the inverter. The inverter has two connections, one on each end. With the laptop screen facing you, look at the left side of the inverter. Pin 1 is the top metal flange pointing to the right.

Step 3

Secure the negative probe (-) of the multimeter to any bare screw. There should be a screw securing the inverter to the laptop that will be perfect for the negative ground connection. Turn the laptop on to test the inverter.

Step 4

Turn the multimeter on and check the multimeter reading. If the display records voltage going to the inverter, such as 19 V DC, the inverter power supply is working. Turn the laptop off.

Step 5

Unplug the LCD inverter connection on the right side of the inverter. This disconnects the backlight from the inverter.

Step 6

Plug a working backlight to the connection on the right side of the inverter.

Step 7

Turn on the laptop. If the screen lights up, the backlight lamp is bad but the inverter works. If the screen remains dark, the inverter is bad.

Tips & Warnings

  • Use the multimeter carefully. If you have never used one, you may want to skip this step to avoid shorting out the inverter or the motherboard. This test has the potential to do serious damage to you computer if done incorrectly.