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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September 27th, 2007 at 5:44 pm
Cheryl,
It’s hard to tell what is wrong until you test the laptop with a known good backlight lamp. Sorry, I know that most likely you don’t have it so you’ll have to guess.
If you replaced the inverter board two times already but still experiencing the same issue, most likely it’s not the inverter problem. Could it be a faulty backlight? Yes, absolutely, but it also could be a faulty video cable or even motherboard. If I would have to guess, I would go with the backlight lamp.
It’s hard to troubleshoot these kind of failure without proper equipment.
September 27th, 2007 at 5:32 pm
Hi, I just replaced my inverter and still have the same dim screen. Only viewable with a flashlight. It happened suddenly though. No flickering. I can use an external monitor so it isn’t the video controller. So it must be the lamp, right? (Unless I got another bad inverter). Your thoughts are appreciated. Thank You.
September 27th, 2007 at 12:46 pm
Teo,
Sounds like you might have gotten a bad inverter board. The original inverter didn’t work at all and this one works for some time, right? Could be bad inverter.
September 26th, 2007 at 11:21 am
I have a hp pavilion dv1000. Originally the screen was dim and could see screen with a flashlight so i thought it was the inverter bought a new one off ebay replaced it. turned it on it worked fine for 10 mins all fine but once i closed the laptop and openeed it again same problem occurred the screen would go on for a second and go dim again. i waited 30 min for it to cool down i turned it on it works fine now again untill it gets hot like lets say 20 mins of using it and once u close or press the lid botton the scren stays dimmed untill you totally turn off the notbook leave it for it to cooldown.i dont know if it could be the inverter again or the LID botton that could be stuck and doesnt let a full power connection to be made.
September 22nd, 2007 at 4:24 pm
I have an HP dv1000 with the exact same problem. What are you doing about it? Where did you get the part?
September 18th, 2007 at 9:33 pm
Javier,
I’m sure 100% the problem is not related to the inverter board.
Did you check out the motherboard for any visible liquid spill damage? Check out the video cable, maybe water somehow got inside the video cable or the video cable connector on the motherboard and it’s causing the problem.
Stop using the laptop as soon as possible. Open it up and let to dry out. I hope it’s not too late.
September 18th, 2007 at 9:24 pm
James Trainer,
Not sure if I can help you here. I do not test inverters with voltmeter, I just use a known good inverter.
Here’s my guess. Set voltmeter to test DC. Put the ground probe of the voltmeter on the laptop chassis and with “+” probe test each wire inside the harness coming to the inverter board. If there is voltage, probably nothing is wrong with the motherboard. If not, try replacing the harness. This is just a guess.
September 17th, 2007 at 10:38 am
Sir,
This website is really helpfull. I but I can still figure out my problem. I drop some water over my laptop keyboard, it was working fine but after 5 minutes the buttom part of the screen started to flicker, then it show a faded image, it came back and work fine. the it did it again exept this time is a white line about 1 inch and a 1/2 thick. It covers the WinXP start icon and when I drag the mouse thru the wihe line the Coursors diisapear. Yesterday the line was gray and this morning it was working fine. When this happens the rest of the screen looks fine except the 1 1/4 inch line that covers the windows bar. I also hook my laptop to an external monitor and the image was good so i know is not the Video Card. Could it be the mother board or the screen inverter?
Than you Sir
September 16th, 2007 at 9:32 pm
I have a acer aspire 3618 ,and need some help trying to figure out if I am getting any voltage to the inverter,the LCd has the faint images and when connected to an external ,everything works. I attached the LCD to another laptop inverter and ribbon ,the LCD checked out fine.I have purchased three new inverters and all do the same thing,nothing ,the backlight remains off. so with a radio shack voltage meter how do I test it to make sure that I am getting voltage to the inverter ,so I can rule out the motherboard and or the inverter cable???Thanks James T
September 15th, 2007 at 1:30 pm
Jessica,
Some laptops have a magnetic microswitch located inside the laptop case. In this case you cannot press on it.
Usually the microswitch is located close to the laptop hinges. Right now I’m typing on a ThinkPad T42 and on my laptop this switch is located on the right side from the left hinge. It’s a small button.