How to replace backlight lamp (CCFL)

posted in: Screen | 274

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.

LCD screen with bad backlight lamp

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.

Remove tape

Removing tape from the backlight cables.

Release backlight lamp 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.

LCD circuit board

The circuit board has been unglued.

Remove circuit board

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.

Open latches

Continue separating the metal frame from the plastic base.

Separate LCD frame

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.

Remove LCD

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

LCD

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.

Transparent layers inside screen

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

Set aside

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

Remove backlight cover

The backlight cover has been removed.

Backlight lamp cover

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

Backlight lamp cables

Unroute the backlight lamp cables.

Release backlight 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.

Remove backlight lamp reflector

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

Backlight reflector

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.

Remove backlight lamp

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

Backlight CCFL lamp

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.

Remove cover

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.

Cable soldered to backlight lamp

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.

Test backlight lamp



274 Responses

  1. cj2600

    Ahmet,

    I have tried replacing the LCD still got the dark screen and went ahead replaced inverter itself and the inverter with the cables, still have the dark screen..What is the last step?

    You said that you replace the inverter with the cables. Did you mean the video cable?
    First of all, I assume that all new parts you installed are in a good working condition. If you replaced the LCD screen, inverter and video cable but still experience the same problem (very dark image on the screen), apparently that’s related to the motherboard. I don’t know what else can cause this problem. I’ve seen that before but it’s not very common. In most cases replacing the inverter board and LCD screen after that fixes the issue.

    By the way, check the lid close switch – a small button located close to one of the hinges. Make sure the close switch moves freely and is not stuck inside the laptop case. When you press on the lid close switch it cuts off power from the inverter board (and backlight lamp). A dirty switch may stuck inside the laptop case and because of that the laptop “thinks” that the switch is pressed down. In this case there is no power coming to the inverter/backlight lamp and the screen remains very dark even after the laptop is turned on.

  2. Ahmet

    I have tried replacng the LCD still got the dark screen and went ahead replaced inverter itself and the inverter with the cables, still have the dark screen..What is the las step? I have replaced the LCD but did not work..Do you think it is the main signal cable????

  3. George

    What is the VOLTAGE GOING to the Pink and White Cables AFTER the Inverter? If I had a power supply to test the bulb directly what would i use?

  4. mindy j gowins

    what is the normal cost to repair the back light if I took it in for repair

  5. Charles Zaffery

    I just replaced a CCFL for my laptop, an Acer Travelmate. I bought a new LCD because mine was dropped by my younger brother and cracked in several places. I got a good deal, but as it turns out, good deals come with a price. The LCD had a burnt out backlight.

    I skipped almost all of these steps because I live in a house with pets and children. Not wanting to contaminate the inside slices I took out the backlight from my old LCD, just tore the whole damn thing apart. It was a 2″ wide assembly that ran across the bottom of the LCD.

    I then proceeded to bend the metal of the new one (very risky, I know, but if I didn’t take it out this way it would’ve never worked again, something would have broke).

    I used 2 eye glass screwdrivers to get the bottom layer set into the unit so that it could provide proper light to the whole thing.

    Bent the metal back into place, plugged everything in, works like a charm. It is a tad too bright in the left/right corners but I’m not worried about it as it works and that’s what matters more then anything.

    I also wouldn’t recommend ANYONE DO IT THIS WAY. DO IT THE RIGHT WAY UNLESS YOU ABSOLUTELY HAVE NO CHOICE.

  6. burning D510m

    update.

    My problem was due to a soldering defect from the manufacturer. I suppose that the high voltage combined with a tight environment started to weaken the rubber pin around the cathode. Once the rubber pin altered, the problem intensified so that it caused some plastic parts to melt, especially one of the corners of the thick reflector layer, and weakened the CCFL glass/electrode (heat effect probably). Hopefully, the LCD matrix wasn’t affected.

    This is a fire hazard Dell and all CCFL based manufacturers should reconsider seriously !

  7. burning D510m

    I have the same problem as blackjack (posted on 2008 jan 12) on a Dell D510m. Besides the flickering and dim lcd problems, I also noticed that the bottom left corner of my screen started BURNING/MELTING and caused some pixels to turn black, while the baclight was working at maximum brightness. When the backlight went completely off, I replaced the inverter and the problem remained. But having disassembled the bezel, I could finally notice SPARKS coming from inside the ccfl casing.

    Before going further in my repair process, does anyone know if a faulty CCFL can cause overheating, or is it just a bad connector, and can it cause the inverter to die ?

    Thanks for the guide.

  8. johan vall

    i have a similiar problem with my screen where i need to use a flashlight to see the screen . i havent gotten as far as replacing the inverter or the bulb. My question is that whenever i open the lid i hear a little buzzing sound from the base of the screen . could that be a bad connection could it be the bulb trying to turn on ?or have i just never noticed this sound before? its very low.

  9. julia howard

    I should be very grateful if you could inform me as to whether cold cathode fluorescent lights (CCFLs) used as LCD backlights use a radioactive material which emits beta particles to start the ionization of the gas unlike the hot fluorescent lamps where the cathode is explicitly heated in order to excite the electrons causing their emission.
    This question is prompted by the Wikipedia article on CCFLs which stated that CCFLs may contain a source of beta radiation in order to start the ionization process.
    As our computer monitor is placed on the only table in the house, use of the table for other purposes means that I have to face the back of the monitor where the backlight can be seen through the grill.

    Looking forward to your response,
    Yours faithfully,

    Julia Howard

  10. cj2600

    Dexter,

    I dismantled the LDC, but it seems that the LCD has leaked (?) at the edge where these lines appear. Can this be correct ?

    I don’t think that you cannot fix it. If the LCD screen has been damaged you’ll have to replace the whole screen.

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