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!
October 25th, 2009 at 10:13 pm
Alobtony,
Sorry, I’m not sure what damped screen means (English is not my native language).
Is it loosing backlight or video? Please describe the failure.
October 25th, 2009 at 9:41 pm
Reben,
First of all, I would check laptop memory. Do you have two memory modules installed? Try removing memory modules one by one. Test the laptop with each module separately. If one of the modules is bad, the laptop should start when this module is removed.
October 20th, 2009 at 9:39 am
I have the T30. I push the power button, all the light, bells and whistles goes on… and then nothing happens.
The thing is the screen doesnt go on and then the pc just idles. doesnt load anything or go on standby or off.
Heeelp!!!!
October 18th, 2009 at 11:26 am
Hi, i have this Hp phoenix laptop, and i’m having a serious screen problem on it. The screen goes damped few seconds after i put it on, Pls kindly help me out.
October 18th, 2009 at 9:00 am
dean,
This description sounds like a problem with the LCD screen. You’ll have to replace the screen.
There is nothing wrong with the inverter. You still can see a part of the screen and it’s bright, it means the inverter works properly.
October 18th, 2009 at 8:56 am
i have a toshiba lap top 17″ screen it only shows half of the screen now .i have hooked it up to a pc monitor and i had no video problems. in the middle of the screen i have color lines runnung up and down and on the left side it has black and white streaks running up and down .but the right side of the screen is ok .so does it sound like i have to replace my inverter or my lcd screen
October 14th, 2009 at 12:03 pm
Sorry I didn’t make it clear in the first post. When the LCD lights up, it only stays on for a second no matter how you move the lid.
Anyhow, I have tried many different things including my magnetic screw driver on the sensor. It only responds to those two touch pad buttons. I’m not sure if it is magnetic sensor any more. The two touch pad buttons do look like metal.
Here’s what I’m thinking. The sensor sends out a signal that the lid is closing, the computer gets the signal, and for some reason, it lights up the screen for a second before it shuts down the screen. Is that normal? Does that mean backlight and inverter are working fine?
Thanks for your time,
Sam
October 13th, 2009 at 10:26 pm
Sam,
This is a very weird problem. So, the screen actually lights up when you CLOSE the display, correct? Really strange.
Maybe the magnetic sensor is not working properly. That’s my guess. Find a small piece of magnet and try activating the switch while the screen is open, kinda make the laptop “think” that the display is close. Can you light up the screen when the switch is activated?
October 11th, 2009 at 10:29 pm
Hi, I have this strange problem with a Sony Vaio Laptop. The screen is very dark when computer’s running. You can still see it though if you try really really hard.
The weird thing is when I close the lid (to the point the magnetic sensor goes off I guess), the screen suddenly gets much brighter and I can see things on the screen just like normal. But if I open the lid again, the screen goes back to black.
I tried external monitors with both VGA and S-Video ports, none of them worked. Which makes me wonder maybe it’s the video card or the motherboard? What do you think?
Thanks
October 6th, 2009 at 7:19 am
Hi Again!
I was reading all site (you have a really good one!!) and I find some more information about my problem (but i have no idea how to fix it, yet…)
I’ll try to be more specific using u’r own pictures
My problem is in the conector number 3 of this picture:
http://www.laptoprepair101.com/wp-images/video.gif
and looking this picture:
http://www.laptoprepair101.com.....ter-02.jpg
i can see a few colors cooming from the video cable:
pin 7: blue,
pin 6: green,
pin 5: yellow
pin 4: orange
pin 3: red
pin 2: ?
pin 1: ?
my question is: is the same order in most cases? I understand it is my own risk, so can i try this order in the inverter of my HP compac 6720s?
thanks for your time and for this site