Do you have a problem with the backlight on your laptop? If yes, you are not alone, that’s one of the most common laptop problems. In most cases the screen inverter is the culprit. Here are some LCD screen backlight failure symptoms that could be related to a bad inverter board:
- Laptop boots as usual but after some time the screen blacks out. You still can see an image on the screen but it’s very dim. You might even use a flashlight to see it better. Sometimes the backlight comes back for a while but then goes off again. In some cases you can turn the backlight on if you tap rapidly on the lid close switch.
- The screen always stay black and the backlight never comes on but you still can make out an image on the LCD. It’s dark, but the image is still there.
-In some cases you might hear a buzzing noise coming from the area where the inverter board is located, it’s on the bottom part of the display assembly.
NOTE: if you cannot see an image on the screen (not even very dim image), most likely you have a different problem and there is nothing wrong with the screen inverter.
Other related articles:
Laptop has bad video on the LCD screen. What is wrong?
Notebook display assembly diagram. How image appears on the screen.
How to troubleshoot and fix laptop video problems
How to replace laptop backlight lamp (CCFL)
Here’s an example of replacing the FL inverter board on an IBM ThinkPad T41 notebook. This guide will work fine for any other IBM notebook. Replacing screen inverter on other notebooks like Dell, HP, Toshiba, etc… will not be much different.
First of all, unplug the AC adapter and remove the battery.
In order to access the inverter board you’ll have to remove the LCD screen bezel. On most laptops screws are hidden behind screw seals. In this case we have 5 screw seals on the front. Carefully remove the seals with a sharp object and glue them on the LCD bezel, in this case you will not lose them. Remove all screws and mark them somehow so you are not confused when you assemble the notebook back.
Some laptops also have screws on the side of the display. This notebook has 3 screws on each side. Remove screws seals and then remove screws.
Start removing the LCD bezel with all fingers. Carefully wiggle the bezel to release plastic latches. Never use any sharp object during disassemble because you can accidentally damage the screen.
If latches are very tight you can use a guitar pick to unlock them. Insert the guitar pick between the LCD bezel and cover and carefully move it alone the side.
This notebook allows you to replace the inverter board without removing the LCD bezel completely. Lift up the bottom part of the bezel and remove one screw securing the inverter board to the LCD cover. This location is very common for the screen inverter. On most laptops you’ll find it under the display bezel below the screen.
Carefully lift up the FL inverter and rotate it a little bit. Unplug cables on both sides. The left side of the inverter board connects to the video cable, the right side to the backlight bulb (CCFL tube) inside the LCD screen. Remove the inverter and replace it with a new one.
To find a new inverter board (and any other spare part too) for any IBM notebook you should use the FRU number from the part.
If you find this article useful, please consider making a donation to the author. Thank you!
March 11th, 2010 at 3:53 pm
I am looking to make a donation and I appreciate the assistance but where can I purchase the lights.
March 11th, 2010 at 2:12 am
Hi, I have a IBM T43 with XGA LCD. If I want to upgrade the LCD to have a SXGA I need also another inverter or I can use the one that I have? What about the LCD cable that is going to the motherboard, it need to be replaced also?.
Thanks
March 6th, 2010 at 5:55 pm
I have a toshiba satellite A200. When i start my laptop the screen goes grey right from the beginning. Then the sides slowly turn black. If i connect a monitor to it, then it works fine, i can see everything on the monitor,, but not on my laptop display. Can anyone suggest any solutions
March 3rd, 2010 at 10:30 pm
shane,
If you replaced the inverter board and LCD screen (with backlight) but the problem still exists, most likely this is the motherboard failure.
Also could be the video cable failure but it’s not common.
I assume that your new inverter and LCD are good.
March 3rd, 2010 at 5:31 pm
I have a Toshiba Satellite L305-S5908 laptop and the monitor went dark. Computer is still working fine, with the back of the screen off i can see everything fine in bright light. I replaced the Inverter, Light tube and LCD screen but still no fix. Anybody know what else i can check? Thanks for your help
February 28th, 2010 at 3:15 pm
cj2600,
I have already reseated the cable connection but couldn’t find the inverter that is why I thought it built into the motherboard.
Thank to your suggestion I will try to replace the LCD next, it is 13.3″ TFT, Unipac UB133X01 and I am not sure it is easy to find.
I appreciate very much for your insight helping me to narrow down the process!
February 26th, 2010 at 2:44 pm
CK828,
1. Bad connection between video cable and LCD/motherboard. Try reseating connections.
2. LCD screen failure (more likely).
3. Video cable failure (less likely).
This is not related to inverter failure, that’s for sure.
February 25th, 2010 at 2:39 pm
For repaircom!
My inverter KUBNKM035A Compaq EvoN800V
Help
Thanks
February 24th, 2010 at 1:39 am
Hi,
my friend HP Omnibook 900 screen got all red but no picture in it, however the laptop is working OK with a external monitor. Please tell where should I check to correct the problem, thanks.
PS. Is the LCD inverter in this model built into the motherboard?
February 23rd, 2010 at 9:23 pm
This is an update to my black screen problem (see 535). I have a Toshiba M105-s3041 (14.1 screen) laptop and the screen went black one day. I had been using it with an external screen with no problems. I replaced the inverter board for about 7 dollars, but no change.
It was suggested (cj2600 – thanks for your help) the problem was the LCD backlight Lamp. You can pick those up for 6-12 dollars (w/o wiring), but the backlight lamp is not as easy an installation as opposed to the inverter board.
I also have a 14.1 Compaq laptop that I dropped 3ft about 6 months after I bought it, and that cracked the inner LCD screen layer. At the time they wanted five hundred to replace the LCD, almost as much as the laptop cost. However that backlight Lamp still worked, so I figured I’d try to put it in the Toshiba M105. If I was unable to do the installation right, I’d just replace the whole LCD screen.
Presto, the lamp swap worked! It was as not as hard an install as I thought, but still you have to work gingerly with tiny screws and tin framework. The lamp is as long as the screen, kind of a mini floresent lamp about the diameter of pencil lead.
I had only one problem with the repair. When I put it all back together I did not get the lcd backlight frame snapped in evenly, and this made dark screen flare on the right and left side of the screen. By re-seating it, I got rid of the flares.
All in all it took about 3 hours to do it. The instructions provided here will give you a good idea of what is involved. Remember to unplug and remove the battery. You will need a phillips eyeglass screwdriver, plenty of space to work, and a cup to put your screws.
There is only one thing I like better than fixing something myself, and that’s the money I’m saving.
Thanks to everyone!