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, 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.
September 16th, 2008 at 12:21 pm
Hi cj2600, There did appear to be a light on the cracked screen, I can see a faint image of whatever I am doing on the new screen. At the moment I am using an external monitor which is ok. Thanks Colin
September 15th, 2008 at 10:45 pm
Marc,
Could be defective inverter board. Try replacing it again if you can.
September 15th, 2008 at 10:36 pm
Colin,
Did you have light on the cracked screen? I mean, did it light up after you dropped the laptop?
Can you see a very faint image on the new LCD screen?
Test your laptop with an external monitor. Can you get the external video? If not, check the memory module. It’s possible the memory module popped up from the slot. Reseat the module.
September 15th, 2008 at 10:20 am
WOW! WOW! and WOW! just by tapping on the little button the screen came back on!
September 14th, 2008 at 12:46 pm
I was just wondering where I would find a FL inverter board to replace my broken one. Thanks!
September 13th, 2008 at 8:12 am
Hi, I have a Toshiba satelite Pro, it got dropped and cracked the screen. I have replaced the screen and back light inverter but still have no light, can anybody help?
September 12th, 2008 at 3:58 pm
I had a similar issue. In my case, I changed the inverter and the screen worked again for 2 days, then it once again went so dim
I can’t see it. Does it sound like I got a bad inverter? Or is it a coincidence it worked for a while after replacement?
September 9th, 2008 at 6:16 pm
Edward Nilges,
Could be defective inverter or bad backlight. I really cannot tell you (and no one can tell) without testing your laptop with known good equipment.
Probably you still have warranty from PCHub? I would try replacing the inverter again, just in case.
September 5th, 2008 at 4:21 pm
Hi, I’m experiencing lack of backlight on a Compaq Presario B1800, except for a moment after power-up and whenever the lid close switch has just been released. I can make the backlight stay on longer if I turn down the brightness, but having the power adapter connected makes it go out much quicker. I purchased a refurbished inverter from PCHub, but I’m experiencing the same problem, though perhaps it stays on a little longer and I can turn the brightness up a notch. When the backlight does light, everything looks as it should.
My question is: do these symptoms indicate that both inverters are faulty, or could it be the backlight itself? Thank you for this excellent resource!
August 25th, 2008 at 10:50 pm
Phil,
1. It’s possible that your new inverter board is defective.
2. There is a problem with the backlight lamp. The backlight lamp (CCFL) is located inside the LCD screen and it’s hard to replace. You’ll find an example in this post: How to replace laptop backlight lamp (CCFL).
It’s way easier to replace the whole screen, but it’s way expensive too.