We get a lot of calls about this and we would like to answer a few questions in this article. To better understand the troubleshooting behind problems with laptop LCD screens you should know what components are involved.
First you have the actual LCD screen. The LCD screen is what displays your computers interface. It has tubes in it that are lit up by power generated from our next component, the inverter. The inverters job is to power these tubes to light the display. It doesnt stop there though, the inverter is connected to a cable that is in turn connected to the motherboard of the laptop. Sometimes these cables have small switches on them that are used to shut the LCD off when the screen is closed. Finally we have the video card on the motherboard of the laptop. These can be built right into the motherboard or can be standalone cards that can be replaced.
Now lets start troubleshooting some of the most common issues people have with the LCD:
A=most likely cause and resolution
Q: You boot your computer up and the LCD is black but the computer sounds like it is booting up?
T: Take a small flashlight and hold it against the LCD screen while it boots into windows. Can you see the desktop now, but very dimm? If you can see the desktop, then connect the laptop to an external monitor and boot it up, can you see the desktop on the external monitor fine?
A: If you answered yes to these questions then you most likely have a bad inverter, and in some cases you could have a bad LCD (backlight issues). By connecting it to an external monitor we have concluded that it is not the video card that is the issue. What we do first is to test the inverter, if that passes we will install a working test LCD to determine if the original one needs to be replaced.
Q: Again, you boot the computer up and the LCD is black?
T: You held the flashlight to it and dont see the desktop at all but you connected it to an external monitor and it works.
A: In this case we would first take a look at the LCD cable, then the switch and finally the LCD itself. Most of the time a bad cable is the culprit, but bad LCD can also cause these issues.
Q: Same as above, you boot the computer up and the screen is black?
T: You do the flashlight trick, nothing, you connect it to an external monitor, nothing… you are bummed.
A: In a case like this it may be your video card that is the issue. On most laptops the video card is built into the motherboard and not easily replaced. Installation of a new motherboard is usually needed. If you have a laptop with a separate video card then you are in better shape as these can be easily replaced without having to replace the entire motherboard.
Now this is just a quick reference on diagnosing LCD issues, this is not the end all be all but it is a good start to finding out what is wrong with your LCD.
If you have any questions or would like us to diagnose and fix your LCD issues, please give us a call at 508-443-3402, or email
We don’t recommend you take apart your laptop to test any of the internal components as some of them contain high voltages of electricity and you can either hurt yourself or damage the computer further.
Thanks for reading!
New England PC and Web
Posted on January 19th, 2008 | filed under PC Hardware |