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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July 11th, 2007 at 8:41 pm
telsiz09,
Make sure the lid close switch (if you have any) is clean and is not stuck inside the laptop case. Clean it up and make sure it moves freely.
If you still can see a faint image on the screen and cleaning the lid close switch doesn’t help, then next step would be replacing the inverter board. I cannot tell you if this is the backlight tube or the inverter board problem, you’ll have to guess. I would go with the inverter board first.
July 11th, 2007 at 7:37 pm
Ostap,
If the beer was spilled only over the keyboard and it didn’t go inside the LCD screen, then most likely the old inverter/backlight lamp/LCD screen weren’t damaged and they are good. I don’t think that internal display parts can by damaged because of the beer spill on the keyboard. Doubt it.
You said that after the motherboard replacement the image on the screen is visible. Do yo get the same result (visible image without backlight) with both old and new LCD/inverter board? Did you try different combinations as old inverter/new screen, new inverter/old screen, new inverter/new screen, etc…? If you tried it but still cannot light up the screen, then most likely the motherboard is not functioning properly or the video cable has been damaged and has to be replaced. Sorry, I cannot narrow down the problem. In this case you’ll have to guess.
July 10th, 2007 at 9:00 am
Ok. I found the matching inverter for my laptop LCD. I replaced the inverter and I get the same results. If I stare hard enough, I can see the images on the screen so it sounds like the symptoms mentioned on this site for a bad inverter. Might it be a backlight problem? Any suggestions?
By the way, regardless of the results, your site was very helpful in replacing the inverter. Thanks!
July 10th, 2007 at 12:48 am
I have a hp omnibook XT 6200 my laptop last night ( black screen) but Display see windows logo and etc. My problem is inverter or Backlignt tube? A lıttle know english Excuss me.. Thanks….
July 9th, 2007 at 5:09 am
The beer was spilled only over the keyboard – missing the screen. I bought the motherboard on eBay – it appeared to have been pulled from another machine.
Your hunch is that the video cable is the last link that may be faulty?
Many Thanks!
July 8th, 2007 at 7:22 pm
Ostap,
You’ve replaced almost everything connected to the backlight, except the video cable. At this point you can only guess what is wrong.
Did you spill beer on the screen or it didn’t touch the screen at all? Did you purchase the motherboard from a reliable source?
July 6th, 2007 at 6:49 pm
Great site!
A few weeks ago some beer was spilled into my Gateway MP8708. I’ve since replaced the motherboard with great results except for the display being dim – an image is visible, but only with a flashlight. I went on to replace the inverter #AS023217020 with no improvement. Rather than fuss with soldering new backlights, I swapped out the 17″ LCD display (Samsung #LTN170x2-L02) for a new one – result was same dim LCD image.
Should I be double- and triple-checking the wire connections for a proper seat, or am I missing something more fundamental? Perhaps the switch that turns off the backlight when the lid is closed? The image is there, just can’t get it to light up… Please help!!
Many Thanks!
July 3rd, 2007 at 11:38 pm
Michelle,
I think you should try replacing the inverter board.
July 3rd, 2007 at 5:44 pm
My back light does not stay on, but it appears for a second after pushing the button that turns the light off/on. The button is not stuck. I just push and release, and the light is on for a second. I can do that repeatedly. Does this mean there’s a connection problem or I need a new FL inverter? I have a Compaq Presario v2000, 2 years old. Any advice would be great! Thanks.
July 2nd, 2007 at 10:31 am
It sounds like you have a drive conflict. You should remove the current video driver and reinstall the most recent driver from IBM. You should also adjust your refresh rates to what works. Default is usually 60hz. I would also verify the problem by using F8 and go to VGA mode and see how the PC acts. If it is stable, Update driver. BSOD?? You have a hardware driver issue and need to see what you added that may cause this??