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 (not even very dim image), 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!
September 20th, 2011 at 1:04 pm
@ abitya,
Connect your laptop to an external PC monitor and test.
Does it work properly with the external monitor?
September 20th, 2011 at 8:15 am
Hello friend
my IBM thinkpad T30 creating problem from last 2,3 days
screen of my laptop not showing anything sometime it automatically start and work very well after 1/2 hour or one automatically start blinking than disappear everything (error show>> prepare stand by) in a day it work 1 or 2 time whats wrong i don’t know
is it possible it because of moisture?
or
need to change display of my ibm thinkpad t30?
please guide me
Thank you
urgent this time my laptop working very well
September 17th, 2011 at 6:51 am
@ Mac,
I don’t think so. If the laptop has a very dim display, most likely it’s either bad inverter OR failed backlight lamp inside the screen.
If you have to guess, try replacing the inverter board first.
September 16th, 2011 at 7:37 am
Hi,
I have an HP 550 in which the inverter appears to have expired, there is a very dim display, I used an external VGA monitor for some time but the vga output has also failed now, is there any link between that dim display and the lost vga output.
September 15th, 2011 at 11:20 am
Steve, it seems your inverter is not broken but the florescent is nearly die. you should change it first.
September 15th, 2011 at 11:19 am
Steve, it seems your inverter is not broken but the sceen data cables may corrupted. Take a look at that cables first.
Good luck!
September 1st, 2011 at 7:39 pm
Hi
I have a Dell Inspiron 6400.
Yesterday the screen flashed and now there is a pinkish/redish like blemish to the right hand corner of my screen. I am assuming this is a problem with one of the backlights?
Does anyone know if this problem can be fixed???
Thankyou in advance.
August 18th, 2011 at 5:14 pm
I have a dell inspiron m301z, which has a cracked screen. When running on battery can see screen clearly, but as soon as i plug in mains charger, backlight goes off.It only does this if there is a mains supply, screen comes on as normal if charger is connected in but not plugged into wall socket. Any ideas?
Many Thanks
Paul
August 16th, 2011 at 9:50 pm
If the problem is:
1. after some time the screen blacks out.
2. there is some kind of buzzing sound
it is for SURE that
- Inverter is failing
- backlight bulb is failing
- Both are failing
to know which one is you have to understand that the inverter transform low voltajes to HIGH Voltajes.
The problem here is that voltajes in the inverter and in the cables of the bulb are high enough to make a discharge through air, when this happens:
- There is the buzzing sound, (zap!)
- Sometimes its visible (spark)
- Sometimes it expels a ozone (smells when its buzzing)
- The backlight turns of inmediatly (it seems that after a discharge occurs there is a protection system that turns of the inverter, you can turn it on again with the lid button, or even you can unplug the cable that supply power to the inverter and reconect it)
Also remember that high voltajes are present from the trnasformer (in the inverter) any circuitry after it has high voltajes and can give you a discharge which is not mortal but its a bit painful.
so identify where is the problem and replace the part that is giving you the problem.
August 12th, 2011 at 12:25 pm
@ Lisa,
Probably there is a problem with the backlight lamp. I guess the next step would be replacing the screen.