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!
April 11th, 2008 at 10:08 am
cj2600,
Thanks for the fast response. I have contacted the seller and they are going to replace it so I will try another inverter. Sometimes I can get the screen to work for hours then it goes dim. If i undo everything and turn the laptop off for a little while it will work for a while before going dim again. Hopefully the new inverter will fix it. Thanks again
April 11th, 2008 at 9:45 am
Zack,
If the new inverter would work the same way as the old one, I would suspect the backlight lamp. But you said the new inverter worked for several hours. Could be bad inverter again. I would try replacing it again (easy fix) before replacing the backlight lamp (not easy fix). Can you ask the seller to replace the inverter board and try it?
April 11th, 2008 at 1:05 am
Oh yeah, I’m tying to fix a Dell Inspiron 8600
Thanks for your help!
April 11th, 2008 at 1:02 am
After reading through this I was sure I had an inverter problem. The screen would work for a few seconds or minutes, then go dim. So I replaced the inverter with a “new” one I bought on eBay. The new inverter worked for several hours and I was sure it was fixed but sure enough the problem came back. I bought a new flex cable and replaced that but no luck.
Could it be the backlight? If i reseat the video cable it will light back up for a minute or so then dim again.
PLEASE HELP!!!!!
April 9th, 2008 at 9:12 pm
Mariel de Jesus,
Check the video cable, make sure it’s properly connected to the back of the LCD screen. Try reconnecting the cable, it may help.
April 9th, 2008 at 5:31 pm
Never mind (re #243). One of the wires on the CCFL had broken off, occasionally making contact. Must have been a bad soldering job to begin with. I swapped in a new bulb even though the old bulb and inverter were probably fine. Now everything works.
April 6th, 2008 at 7:04 am
Hi …thanks for your advices. My laptop is a HP Pavillion ze5375us. I had the same problem, screen was black. I already replaced the inverter, but now my screen is white ( all you can see is like a bright light, but any image).
Now what else can be the broblem…what can I do???
April 3rd, 2008 at 11:30 am
I replaced the inverter in my Dell Inspiron 4150. Now the screen lights up for 1 second then go dark and stays dark until I power cycle the machine. External displays work fine. I can see the faint unlit display so the panel appears OK. Any ideas?
March 30th, 2008 at 12:50 am
I have a problem with the LCD of my dell D 600.
its blank on when turned on.
what do you advise i do?
thank you.
March 28th, 2008 at 12:22 am
Thanks so much for your website! Using the information I found here and on one other site that you posted a link to, I took apart my laptop to see what kind of inverter I needed (backlight wasn’t working). Turns out, the inverter was fine, the only problem was that the connection between the inverter and the backlight lamp was loose! I plugged it back in and haven’t had a problem since!