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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December 11th, 2007 at 2:21 pm
I have a T41 with the same problem described and was wondering if I can just remove the inverter/LCD screen (unplug it) and use the machine as a “desktop”
December 7th, 2007 at 6:39 am
Hi,
A couple weeks ago, the screen of my Dell Inspiron E1505 started appearing pinkish and flickered. After a day or two, the screen went to black and I could barely see the image. I use the laptop with external monitors so I knew the system was working fine otherwise. Based on the symptoms, I deduced that it was the backlight.
From what I’ve read, it’s really difficult to replace just the backlight (at least on Dells). I couldn’t afford to be without the laptop for even a day so I bit the bullet and bought a new screen (w inverter attached) online.
I followed Dell’s instructions to replace the screen, which meant literally taking half the laptop apart (is that necessary?)
Anyway, it worked fine for about a month and then the screen went black, just like before but without the pink stage.
I called the company that sold me the screen and they suspected it might be the inverter and sent me a new one.
They suggested I first put it on my old screen and to try reinstalling that. I did and it started up fine but within minutes the screen was pinkish and then went to black. This seems to confirm that the first screen indeed had a backlight problem.
I took the laptop apart again and reinstalled the newer screen with the new inverter. That worked, which seems to indicate that the second screen’s inverter was the culprit.
My only issue now is that the screen seems dim. I use the brightness control but that doesn’t really make any difference. When I try, the screen flickers for a second like it’s adjusting but the brightness maybe varies 5% from the top to the bottom setting.
Any ideas? Though I’m happy to have the screen working again, I’m considering trying to install the original inverter (I had to get a little rough to get it off the original screen) or trying another one. Could the inverter be causing the brightness problem?
The tiny pink wire that connects the inverter to the screen has a tiny wear mark on it so I can see a little bit of darkness of the wire inside. The wire’s not exposed but perhaps it was pinched before. Possibly the culprit?
Also, in your experience, can I use method on this page or is there something particular about the Dells where you have to take them all apart? Doesn’t seem like it in retrospect but, my first time in, I didn’t want to take any chances.
Any perspective on the whole experience would be greatly appreciated. Thanks!
December 3rd, 2007 at 11:55 pm
Lee,
That’s what I do. I have two test backlight lamps I removed from old cracked LCD screens. These lamps have two different connectors and I use these lamps with all laptops where I have to troubleshoot the backlight problem. Never had a single problem.
December 3rd, 2007 at 4:29 am
Can I connect Any Backlight to Any Inverter “just for testing”?
I have a good backlight but the connectors wont fit into the “possibly” faulty inverter that I have.
If I cut the cables and make them fit, would this be safe?
cheers
November 17th, 2007 at 11:41 am
I own A T-21 Thinkpad with a backlight/inverter/lid switch
issue
Iam trying to find out which
when the laptop is running on ext, moniter its ok
when the lcd screen is working I can adjust the level of
brightness
does that mean the inverter is ok
when the lcd is blank I can see the screen with the help
of a flashlight
also when the screen is dark ,the only way I have been able to
get it back is by actually turning laptop upside down and partially closing and fully opening lid whil pressing on parts of laptop
which makes me think the problem is either lid switch or loose connection somewhere ., my laptop is missing one screw from the bottom and the front right section of keyboard where the arrows are below the right shift key lifts up and is not attached our t40 is not like this the t21 can swap cd to floppie I do not remember if it was always like this
can any other T-21 owners let me know
this is a helpful website I could not find right part # for inverter from Ibm (10L1402) thats what they list ,but when you try to buy it they dont acceot that as part #
I dont want to replace it and find it is ok
October 24th, 2007 at 4:42 pm
Hi there, it is me, Cheryl. … seeming to have a never ending story with the lcd problems…. After replacing the video cable and checking out the lid close switch… which could actually be the problem… I did some research and found out that for the HP series zd7000 there is what HP calls a Global alert or ADT. It concerns video problems… (I think it is due to the GPU or something on the motherboards that has consistently gone bad on the zd7000.) They are replacing them… the motherboard… free of charge… My laptop is out of warranty, but they are still replacing it free of charge. I am hoping that this will fix the problem… If anyone has questions… Chat with them (HP) and mention the ADT ID # 1760…. Some web forums mention a global alert from april of 2006 around the 20th. Not sure if you need all that informaiton …. The tech today found it with the ADT#… for a better description of this you may check out the forum at: http://www.r3000forums.com/vie.....amp;t=6518
I hope this helps someone… not sure if it applies to other z series notebooks… Thank you cj2600 for your help in diagnosing my problem.
October 18th, 2007 at 9:30 pm
Pedro,
Did you remove the CPU during the disassembly process? If you did, make sure the CPU is properly seated inside the socket and the socket is locked.
Check the memory, it may not making a good contact with the memory slot. Reconnect the memory module.
To start any laptop with video you need only three main parts: motherboard (I assume the video card is integrated into the motherboard), processor and memory. If these parts are not defective, you should be able to get video.
If there is no video, either you have bad parts or there is some kind of connection issue between these parts.
October 18th, 2007 at 7:35 pm
hi i have ave a hp pavilionzx5000.
i try to open a prt of it ,but when i put it back together . nothing on the screen is like no power on it .please any body can tell what can i do .or how to fix it. .
October 16th, 2007 at 8:39 pm
hany,
I think I know what you are talking about because I have the same problem with one of my laptops, it’s a Toshiba Satellite 3005. Unfortunately I didn’t have time to find out what is causing the problem but I think it’s related to the backlight lamp.
From my experience, when you have a faulty inverter board the backlight either work or not. But in my case the backlight works all the time but the screen kinda flickers, changing the brightness and I think it happens because the backlight lamp is failing (it’s located inside the LCD screen).
October 16th, 2007 at 9:00 am
hello i have a problem with my backlight,sometimes it works fine and then it becomes like flashing,the light increases and decreases in a hesitated manner like an old tv can u help me if it is from the lcd it self or the inverter???