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.
If you find this article useful, please consider making a donation to the author. Thank you!
July 20th, 2007 at 7:07 pm
Joaquin,
Replacing the backlight lamp is not an easy task, I have never tried it myself. I would probably try it on my own laptop but if you are doing it for your customer it’s a different story. What if you damage the screen? What if you break the CCFL tube? Do you know what is going to happen? Yep, they will blame you. And this job will turn into a nightmare. If you can get out by replacing the screen, just replace the screen. If you search here for “Inspiron 6000 screen”. You can find many offers, you can buy this screen for about $200. It is MUCH easier to replace the whole screen then changing the CCFL lamp.
Thanks for the link by the way.
July 19th, 2007 at 7:44 pm
I really appreciate the info on your site!! I just replaced the Inverter in a Dell. With both the old and the new inverter the video is fine for awhile, then screen goes dim. External monitor video is fine. Even if I bought a defective inverter I don’t think the problem would be identical. The Dell was dropped off a bed before this problem started. Could it be the backlight itself?
Thanks
Lee Johnson
July 16th, 2007 at 6:37 am
Hi CJ2600,
No I have not been inside the machine yet. The user came to me with the pink screen and I started researching and then an hour later they came back to my office saying the screen was black which we later determined was actually just really dim.
My boss had me research what it would take to repair it which is what led me to your site. To tell you the truth I was hoping it was an inverter because it seems those are easier to replace unlike a CCFL. I researched replacing CCFL’s and it requires going deep into the screen assembly and desoldering and resoldering the CCFL.
I found this demonstration of replacing the CCFL on a Inspiron 8000 (mine is a 6000):
http://www.lcdpart.com/images/TX41D56VC1CAA.pdf
Do you think this procedure is doable or am I just intimidated because it requires soldering? Or is it more headache than it’s worth and should I just try to find a replacement screen? Is replacing the whole screen going to fix my problem and is it easier than changing out the CCFL?
July 13th, 2007 at 1:17 pm
Joaquin,
That’s what I think but I can be wrong. It’s impossible to troubleshoot a laptop over the internet and all I can give to you is only my guess.
From my experience, a pink hue indicates a problem with the backlight lamp, it’s failing. Here’s an example of a failing backlight lamp.
Did you try to disassemble the laptop before the backlight went off? Did you try reseating cables inside the display assembly? If yes, then it is possible that you forgot to connect one of the cables.
July 13th, 2007 at 9:37 am
Hi again,
So you’re thinking because it was pink before it went dim that it’s a CCFL issue instead of an inverter? Basically the bulb went pink before it failed completely?
July 13th, 2007 at 9:09 am
Joaquin,
It is hard to guess without testing the laptop with a known good backlight lamp but I would assume that this is a backlight related problem. Is it possible that both CCFL and inverter are failed at the same time? Yes it’s possible but unlikely. You see, the laptop already had bad backlight lamp and it’s possible that the lamp just died on you. Just explain it to your customer and I think she will understand.
Anyways, Inspiron 6000 inverters are not expensive and you can find a new one for about $25-30 here.
July 13th, 2007 at 8:48 am
Hello,
I orginally posted this under a different article and thought this one to be more appropriate for my problem.
One of my users has an Inspiron 6000 that is used mainly with an external monitor. Recently she came to me because the screen on the laptop had this pink hue to it, but the display on the external monitor was fine.
I started to research this and found that bad CCFL’s will cause this. However, later the same day it seems the CCFL went out all together because the screen on the laptop is very dim but you can still make out icons and wallpaper. However the external monitor display is still fine. There is no lid switch that I can see so I’m assuming it’s internal and moving the LCD display and closing/reopening does not change anything.
After reading through all the posts here I guess my question is, even though it had the pink hue which points to a CCFL issue, since it now is very dim do you think it is a CCFL issue or an inverter issue?
July 11th, 2007 at 8:55 pm
Khahn,
In most cases, when a laptop screen looses backlight but you still can make out a dim image on the screen, your problem is a faulty inverter board. From my experience, this is correct for most cases but not all of them.
If you have replaced the inverter board but still experience the same issue, there could be many different reasons.
It can be related to the lid close switch, defective video cable, bad motherboard, faulty backlight lamp or not properly working inverter board.
Unfortunately, there is no way to find out what is wrong until you test the laptop with a known good backlight lamp and inverter board. No one can tell.
You’ll have to test the laptop with good parts.
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.