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 28th, 2009 at 9:14 pm
Well, my post from June 15th was maybe a bit premature. I replaced the inverter (in my Mom’s laptop) due to the black screen. You could just barely make out an image if you got the right angle of light on the screen. The laptop worked great for two weeks. Just got an email that it’s back to the same problem with a dark screen. I ordered the replacement inverter from lcdparts.net using their link posted in this article. Could I have maybe gotten a bad inverter? Or does this sound like the inverter is not actually the problem?
June 27th, 2009 at 11:37 pm
Kamykaze,
It’s not related to the inverter. The backlight is on, so the inverter works properly.
Can you get image on the external monitor?
June 27th, 2009 at 11:48 am
REPLY to Sharon:
Laptop LCD backlight mostly consists of 4 different parts: Laptop inverter, laptop LCD lamp (CCFL) , inverter cable and toggle switch. Failure of any of the component will give similar symptoms. There is no other way to find out what might be wrong as long as you don’t use tester equipment. Possible causes of lamp failure is laptop age, continued usage of LCD. Inverter failure is mostly due to variation in power source to LCD or laptop. Sometimes physical breakage and pressure impact also causes backlight failures. Toggle switch issues are very common with HP and Compaq laptops. Toggle switch is On Off switch which turns light off on laptop LCD when laptop bezel is closed. Inverter cable is a bus which runs from motherboard to inverter. Function of inverter cable is to run power from motherboard to inverter. Possible cause of failure is hard impact of pressure or breakage on laptop as cable is situated inner side of laptop and normally does not tear out with age. In worst cases Bad Motherboard and bad LCD cable ( flex cable ) can also cause backlight failure.
June 23rd, 2009 at 2:32 am
Hi
and what if only the backlight works on an LCD and no other output can be seen?
is it inverter or LCD failure?
June 22nd, 2009 at 2:49 pm
Can a laptop (in my case, Dell Inspiron 1501) have different inverters parts that are not interchangeable or compatible? I just purchased one on ebay, and when I installed it, My screen still did not light up (See previous posting. So I contacted the seller to arrange for an even exchange, thinking my new one was doa…but the seller says because the part number of the inverter I bought was different than the original one in the machine, I must have purchased the wrong one (they look very similar). So, my question is….can there be multiple inverters for the same laptop model that are not interchangeable?
June 22nd, 2009 at 10:01 am
WoW that was the fastest repair i ever made to a computer!!! Thank you so much for the step by step instructions.
June 20th, 2009 at 11:36 am
Dell inspiron 1501. Had the sometimes dim, sometimes black screen, so I replaced the backlight and the inverter. The backlight does light up but very dimly and only the first few inches of the bulb. Could I have bought a bad replacement inverter or do you think there is another problem? ALmost like there is not enough power to light the bulb all the way. Seems like there must be another problem if the replacement parts didnt change anything, but I don’t know where to look now.
June 17th, 2009 at 5:44 pm
On my 2.5 year old Toshiba Satellite A135, I replaced the inverter but that wasn’t the problem for my computer. My backlight had obviously failed as I could see the images on the laptop screen using a flashlight. But replacing the inverter using the info on this site gave me the confidence to handle replacing the screen myself.
Got a new LCD screen today for $99 from lcdsforless and that fixed the problem (thank goodness). So I don’t have to buy a new laptop and deal with transferring data at least for now. The backlight lamp apparently failed on the old screen, and I wasn’t interested in peforming surgery on the old LCD screen to replace the lamp.
SO glad to have it working correctly as a laptop tethered to a regular display monitor isn’t very portable. And it is nice to have a very bright screen again – in comparison to this new screen (and backlight) I can now see how dim the other one had become before it failed.
June 15th, 2009 at 8:43 pm
Great! Fixed the HP Pavilion dv1000 in about 15 minutes. If you don’t have a guitar pick, the edge of a credit card should do the trick.
June 4th, 2009 at 4:58 am
fixed it myself…thanks to this site.
thank you