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.
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September 27th, 2008 at 10:04 pm
Nikhil,
Can you see a very faint image on the screen? Does your laptop work fine with an external monitor?
September 27th, 2008 at 10:02 pm
Robert Hansen,
Most likely software settings. Make sure the brightness is set to 100% for the AC mode.
I believe on some (maybe all) Dell laptops you can change the screen brightness settings in the BIOS setup menu.
Also, try changing the brightness with Fn+Up Arrow (to increase) and Fn+Down Arrow (to decrease) keys. Can you? Hold down the Fn key and tap a few times on the Up Arrow key.
September 27th, 2008 at 9:56 pm
Kerry,
You cannot tell until one of them replaced. That’s right, you’ll have to guess. I don’t know any reliable way to test the inverter board at home.
Inverter boards fail more often than backlight lamps. If I would have to guess, I would go with the inverter first.
September 27th, 2008 at 9:50 pm
Bryce,
There is a slight chance that your new inverter board is defective. If not, I would say it’s bad backlight lamp. You can try replacing the backlight lamp but it’s not easy.
This post could be helpful: How to replace laptop backlight lamp (CCFL).
September 27th, 2008 at 9:41 pm
Fred Zayed,
First of all, I would try reconnecting the video cable, maybe it got loose. This connector is located under the hinge cover. You can remove the hinge cover following these instructions.
If reseating the cable will not help, probably you’ve damaged the LCD screen.
September 25th, 2008 at 11:20 pm
Whenever I start my Hp pavillion laptop. The display doesn’t show up & it gives a strange buzzing sound though machine seems to be working.
September 25th, 2008 at 5:11 pm
I have a Dell 5160 inspiron laptop. Just recently, noticed that when the power supply is connected, the screen does not come to full brightness anymore. The screen is always partially dimmed as if it were on battery power. Is this a hardware or software issue?
September 25th, 2008 at 12:51 pm
i have a compaq presario v2000. how can i tell if i need an inverter board or a backlight? have a dark screen but i can see the screen with a flashlight. i have been looking thru your web site (which is fantastic!) but both problems are similiar. thanks for any help
September 24th, 2008 at 4:26 pm
I replaced the inverter on my acer-5610. I still have the same problem the back light goes out about 1 minute after the machine boots, I can get it to come back on for a brief period by pushing on the pin switch that tells the machine the display is closed. Any thoughts beyond replacing the back light?
September 24th, 2008 at 12:04 pm
I have a Dell Insprion 6000 that was in the trunk of my car for a couple of days, when I booted It displayed the upper part fine but the lower 1/3 showed lines. can you advise? Thanks