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.
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June 5th, 2007 at 12:29 pm
hi…i have a lcd dell monitor screen not laptop…ok i turn it on..then it lights normally for a few seconds…then goes dim….i can see stuff working in the background..but its so dim…if u can help..plz email me at aly@amdarwish.com and thank u for ure time…by the way i triend connecting it to different computers…but still got the same symptom……ALI
May 28th, 2007 at 10:29 pm
Thomas Gregor,
As Mike suggested check the BIOS power settings.
Check the lid close switch button. This button cuts off power from the inverter board (and backlight lamp) when the display is closed. Make sure the lid close button is not stuck inside the laptop case. Sometimes the lid close button might get stuck inside the case and the inverter board will not get any power, as a result the LCD screen has no backlight.
If a known good inverter board doesn’t help and there is nothing wrong with the lid close switch, you might have a problem with the backlight lamp, motherboard or video cable. It’s hard to say which part is failing, probably you have a bad backlight lamp but this is only a guess.
May 25th, 2007 at 9:35 am
Turn off power mgt in bios, or make sure screen brightness on max in battery mode.
May 25th, 2007 at 7:08 am
I’ve got a problem with a IBM A30p.
Symptoms are as described:
When booting, the IBM-Splash appears (but quite dim), after that everything is dark. Under some light-conditions ic can see the win2k bootsplash and so on.
VGA-Connector is ok.
Replacing the inverter results the same.
Any hints for fixing it???
Thomas Gregor
May 21st, 2007 at 1:35 pm
I have a HP ze5300 with this problem I am attempting to fix. The hardest part so far is removing the screws.
(This is the most common stumbling block in most other types of repairs I’ve encountered.)
I have three of the six out so far. The other three (along the top) I can’t get a grip on with my phllips. I have the screen on the table (keyboard up) as it is easier to remove screws with the screwdriver in the vertical position for better control. I have my notebook on a flat, stable surface and with ample lighting for the dark-color laptop.
I want to avoid stripping out the screws or getting metal bits on my screen. It’s possible they have been affected the most by weather (haat and cold) and so need something to help them out.
Any suggestions? Is there a lubricant that can be safely applied to a notebook screw?
May 20th, 2007 at 2:22 am
llus,
You mentioned that the screen goes dim with the slightest movement. I think it might indicate some kind of connection issue, maybe the inverter cable is not making a good connection with the inverter board. In this case reseating the cable on the inverter board might fix the issue. If reconnecting the cable doesn’t help, I would try replacing the inverter board. You can find a new LCD inverter board on eBay for $30-40.
May 18th, 2007 at 5:09 am
Hi,
My presario 900 laptop screen goes dim after a few minutes once it boots up. When it happens desktop can still be faintly seen thru the dark screen. On occssion the screen has gone dim after a couple of hours, happens with the slightest movement to adjust the screen up or down. Initial repairer queries have said I needed new backlight &/or inverter. & quoted $200+ to repair. It works well with an external monitor. Any ideas/advice on a possible fix?
Many thanks!
Ilus
May 17th, 2007 at 5:34 am
My laptop screen flicks when I pull the lit towards me… It only happens in some angles… It also happens when I turn it on after moving it around. Do you think it may be a lossen cable or something more complex? Is it is a lossen cable, wich cable is more likely to be?
Thanks in advance.
May 9th, 2007 at 6:30 am
hi, i have a T41 EXACTLY the same as your website, but the thing is i’m not too sure is it my screen inverter that is spoiled or what. Cause when ever i plug in my battery, my backlight just goes off, but rather i’m in AC MODE. So i’m not too sure is it my screen inverter spoiled or? pls address my problem thanks!
May 8th, 2007 at 8:13 pm
Rory,
You don’t have to open Pandora’s box, here are instructions. Take a look at this Satellite A20 disassembly guide. Steps 7-11 here show how to remove the keyboard and steps 20-25 show how to remove the LCD screen.
If you feel uncomfortable opening up the laptop, do not do that. Take it to a repair shop instead.