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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February 13th, 2008 at 5:10 am
Richard Muller,
Apparently the motherboard has been damaged. You’ll have to remove the keyboard as it shown in ThinkPad HMM and take a closer look on the motherboard. If you see any corrosion, you’ll have to replace the motherboard.
February 13th, 2008 at 5:05 am
Hunter,
Most laptop LCD screens have only one bulb but it’s very difficult to replace it. The backlight bulb is located inside the LCD screen. Here’s an example.
February 11th, 2008 at 11:44 pm
On the R32 what is the size of the blub I need to repalce the bulb and not sure the size. I do not want to mess with it anymore then I have to, the things in their are fragile.
February 11th, 2008 at 11:19 pm
Hi,
thanks for your informative repair pages.
Before I replace the backlight unit resp. the inverter I want to find out, if the inverter fails or if the fault lies _before_ the inverter.
I poured by accident a glass of wine into my Thinkpad R40 and it went off. Afdter cleaning and drying overnight it started up the next morning but the backlight stayed off. I dont assume that the wine got into the inverter, it just soaked the keyboard. So I think there may be some instance which commands the inverter to power up. Can I measure anywhere on the mainboard if the inverter gets this signal?
Thank you, Richard
February 10th, 2008 at 1:21 pm
Thanks for the tip, Jeff. Maybe we’ll try replacing the bulb(s)?? Is there one or more?
February 9th, 2008 at 8:32 pm
If the inverter keeps blowing, could be older bulbs drawing too much of a load.
February 8th, 2008 at 8:01 pm
Okay, my husband has now purchased and replaced two backlight inverters for our HP Pavillion dv1000. He was able to install them thanks to your excellent photos and instructions. The first one lasted exactly 3 weeks and then went out. The guy we got it from (ebay) made good and sent us another one. Husband installed that one and everything worked fine. Just went out yesterday….exactly 3 weeks again! What the????? Any ideas what might cause this? Since they both worked for exactly 3 weeks I can’t believe it is the inverter. What do you think???
February 8th, 2008 at 4:05 am
Hp Cpmpaq1500 laptop
On display on lcd but on external monitor
display is perfect pls help what could be problem
February 7th, 2008 at 12:04 am
I did some research, looks like a burned out, fast blow fuse, maybe 7amps, my mobo looks exactly like this, http://img148.imageshack.us/im.....184lc8.jpg where the fuse is on the left of the battery :S btw this fuse is about 1/4 a canadian dime, which i don’t think i can solder :S now im looking at electronic componets store to see if they have it and will keep this forum posted, thanks
February 6th, 2008 at 10:32 pm
Joe,
Yes, it could be bad cable or faulty motherboard but I cannot tell you witch one, you’ll have to guess.