Posts filed under 'LCD Screen Repair'

How to replace laptop backlight lamp (CCFL)

In this guide I will disassemble a laptop LCD screen in order to remove and replace the backlight lamp (CCFL).
Replacing the backlight lamp is not an easy task even for experienced technicians. If you do something wrong you will permanently damage the LCD screen and have to buy a new one. Proceed on your own risk and do not blame me.

Some recommendations before you start:
1. Work in a clean room. You don’t want dust and lint inside your LCD screen.
2. Make notes, so you know how to assemble your screen back.
3. Take pictures.
4. Before you remove something, take a closer look at the part and memorize how it is assembled.
5. When you are assembling the screen, remove dust and lint with compressed air. Do not use cloth.

The backlight lamp (CCFL) is located inside the LCD screen, so we are going to take it apart. In this article I’m not going to explain how to remove LCD from a laptop, it’s been covered before.
Here some examples:
Removing LCD screen from a Dell laptop.
Taking apart IBM ThinkPad display panel.
Removing screen from Toshiba laptops.

Remove sticky tape and foil from the back of the screen and glue it somewhere so you can reuse it later, when you assemble the screen.

Removing tape from the backlight cables.

On my screen the green circuit board was glued to the plastic frame with a double sided tape. Carefully unglue the circuit board. Be very careful, do not flex or bend the circuit board.

The circuit board has been unglued.

Place the LCD screen on the side and start removing the metal frame witch secures the LCD to the plastic frame. There will be many latches on all sides of the frame, you can unlock them with a small screwdriver.

Continue separating the metal frame from the plastic base.

On the following picture you can see that frame, LCD with the circuit board and screen base have been separated. Be careful, do not touch internal components with your fingers. Handle all internal components by the sides.

Place the metal frame and LCD with the circuit board aside. You’ll need them only when you assemble everything back together.

There will be a few transparent layers inside. Carefully remove them from the screen base. Do not separate the layers, just put them aside together.

Keep everything organized, so you have no trouble assembling the screen.

Start removing the metal cover from the backlight lamp (CCFL).

The backlight cover has been removed.

The backlight lamp (CCFL) cables are routed through small plastic hooks.

Unroute the backlight lamp cables.

Now probably the hardest part in this disassembly process - removing the backlight lamp and reflector. The backlight lamp is secured inside the reflector so you have to remove both and then separate them.
Before you remove the backlight lamp and reflector take a closer look how it’s assembled and mounted to the screen base. Fitting the backlight and reflector back in place could be a very challenging task.

The reflector is glued to the screen base with a double sided tape.

After the reflector has been unattached from the screen base, you can start removing the backlight lamp. As you see on the picture, I marked the left side of the reflector with a red dot so I know where the red cable goes when I assemble everything back together.

The backlight lamp (CCFL) has been removed from the reflector.

In order to access the backlight lamp leads you’ll have to remove the rubber caps from both side of the lamp. I’m not sure if you can touch the backlight lamp with your fingers, so I would use rubber gloves.

Cabled on both sides of the backlight lamp are soldered to the backlight leads. In order to access the leads you’ll have to remove the black insulator on both side of the lamp.
Unsolder both cables from the old backlight lamp and solder them to a new one.

You can test the new backlight lamp (CCFL) before you install it back into the screen. Connect the backlight lamp into the inverter board and turn on the laptop. The backlight lamp should light up.
From my experience, on some laptops the backlight lamp will not light up until the video cable is connected to the LCD screen. In this case you’ll have to assemble the LCD screen and then test it.

7 comments December 9th, 2007

Troubleshooting laptop with backlight failure

This laptop came for repair because of the LCD screen backlight failure. My customer complained that the laptop LCD screen is black but the laptop works with an external monitor.
Here are my steps for troubleshooting this laptop with the backlight failure.

First of all, I tested this laptop with an external monitor connected to the VGA port and the external monitor worked absolutely fine. I was able to get crystal clear image on the external screen even though the internal screen didn’t light up. If the external screen works fine, then most likely there is nothing wrong with the video card.

Notebook display assembly diagram

After that I took a closer look at the laptop LCD and noticed that the screen is not completely black. The laptop screen still works but the image is very very dull, you barely can see it. It means that the screen still gets data signal from the video card, but for some reason the backlight lamp doesn’t work.
From my experience I know that this problem can be related the lid close switch, faulty inverter board or bad backlight lamp. I checked them one by one.

If you have a similar problem, make sure the lid close witch moves freely. The lid switch is a small button located close to the LCD screen. This button triggers the hibernation or sleep mode when the screen is closed. If the lid close switch is dirty, it might get stuck inside the laptop case and cut off the power from the inverter board. The inverter board works as a power supply for the backlight lamp and if there is no power coming to the inverter board, the backlight lamp will not light up either.

In my case the lid button worked properly, it didn’t stuck inside the case. When I was pressing on the button very fast, I was able to light up the screen but only for a fraction of a second. The image wasn’t bright and it had a pinkish tone. A pinkish tone usually indicates a problem with the backlight lamp, not the inverter board.

Even though I suspected the backlight failure, I decided to test this laptop with a new inverter board just in case. But it didn’t help. The screen didn’t light up even after I replace the inverter board. So, I was right, this problem is not related to the inverter board.

Finally, I disconnected the screen backlight lamp connector from the inverter board and connected my test backlight lamp (I removed it from another cracked screen).

As soon as I turned on the laptop, my backlight lamp lighted up. Yep, that’s the problem. The laptop screen has a faulty backlight lamp.

Here’s another laptop with backlight failure

This laptop video fails in a little bit different way. In this case the backlight lamp hasn’t failed completely.

The laptop starts with video on the screen but the background has reddish tone, the screen flickers and it makes noticeable buzzing noise coming from the backlight and inverter area. After a few minutes the backlight turns off by itself and the buzzing noise stops. When the backlight is off, the image on the screen is still visible but it’s very dark.

I removed the screen bezel and connected my test backlight lamp.

My test backlight works absolutely fine. The lamp doesn’t flicker and there is no buzzing noise. So, this laptop needs a new backlight lamp.

39 comments September 5th, 2007

How I took apart and repaired my notebook LCD screen with water damage

Yesterday took apart and repaired my notebook LCD screen with water damage. The screen itself was working just fine but it had two different problems.

- previous owner spilled water on the laptop. Somehow the water got inside the LCD screen and left stains inside the screen. The water marks were very noticeable on a white background and it was very irritating.
- the screen also had dust and lint inside also very noticeable on a white background. I have no idea how it got in there but I decided to clean it up too.

To fix both problems I had to open up the LCD screen. This was my first experience on opening a notebook screen. I was pretty confident because I didn’t really care if I break the screen, I just wanted to know if it’s possible to fix it.

Warning: the LCD screen can be easily damaged if you open it up. If you do something wrong the screen might become completely unusable and you’ll have to buy a new screen. It’s very expensive. Think twice before you decide opening the screen. Continue at your own risk.

Here’s my Dell Latitude D610 notebook with water damaged screen I’m going to take apart.
First of all remove the battery from the notebook.

Lift up rubber screw seals and remove all screws.

Carefully separate the screen bezel from the LCD cover and remove the bezel.

Remove two screws from the front and two screws from both sides.

Carefully remove the LCD screen from the cover and place it on the notebook base. Disconnect the video cable and the inverter board cable.

On this model the inverter board is attached to the screen with two screws. Remove both screws, disconnect the screen cable and remove the inverter board.

Carefully peel off sticky tape and foil and put it aside. You’ll have to put it back in place during the screen reassembly.

Remove two screws from both sides of the screen.

Carefully place the screen upside down on a flat surface. Carefully unglue the film that covers the circuit board and remove two screws from the board (top circles). I wasn’t really sure if I have to remove screws on the bottom, so I removed them just in case. Do not touch the circuit board with fingers.

After both screws are removed you should be able to lift up the circuit board. Be careful, it’s still attached to the LCD.

Start unsnapping the metal frame from the screen. There are a lot of latches on all sides of the screen. You can unlock them with nails or a small flathead screwdriver.

After all latches are opened you should be able to separate the screen into three pieces: metal frame, LCD and background (not sure about correct technical name).
If you have lint or dust inside the screen, probably you’ll find it between the LCD and the background. Do not touch LCD or background with your fingers. I was able to remove dust and lint up with a very soft cloth, barely touching the LCD and background surfaces.
After I split the screen I found that the background has a few some kind of optical layers (three transparent sheets) and in my case they were damaged by water. The water dried out and left stains between these optical layers.
In my case removing dust and lint wasn’t enough and I had to go further.

Very carefully separate the LCD with attached circuit board from the background.

To remove damaged optical layers it’s necessary to remove metal locks on both sides of the screen. It’s like a small clip that keeps layers in place.

After I removed both clips, I was able to look between the layers. At first I tried to clean up the dried water marks with a soft cloth but it didn’t help. The stains were still visible and didn’t want to go away.
Fortunately I had another similar screen laying around, it had a cracked LCD. I decided to borrow the optical layers from the cracked screen and transfer them to my screen. I wasn’t sure if it’s going to work, but as I mentioned before I didn’t really care if I break the screen. It was just an experiment.
So I disassembled the cracked screen and carefully transfered the white background and all transparent layers to my screen.

After that I assembled my screen back removing dust and lint with a very soft cloth. Breathlessly connected my new screen to the notebook. Turned it on and…
That’s a miracle, it works!
No dust, no lint, no water mars inside the screen! It’s clear and the background is absolutely clean!

My donor screen had a cracked LCD but it had a good working backlight tube. The backlght tube is very fragile and it’s located inside a metal casing. I didn’t remove the backlight tube, I just broke off the entire metal casing from the plastic frame. I’m going to use this backlight tube for testing purposes.

If you fixing a Dell laptop yourself, probably you’ll need a service manual. Some Dell service manuals provide step-by-step laptop disassembly instructions.