Sunday, December 9, 2007

How to replace 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.


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.

Thursday, December 6, 2007

DC power jack repair guide

This guide will explain how to repair a failed or loose DC power jack on a laptop computer yourself.
Disclaimer: I’ve made these instructions only for people experienced with soldering and repairing computers. If you don’t feel comfortable doing this job, please do not open the laptop or you can permanently damage your computer. Take your laptop to a professional repair shop instead.
Use this repair guide at your own risk.

For this repair you’ll need the following tools.
1. Soldering iron or soldering station. I use Weller WES51 soldering station and for this job I set temperature to about 800-850°F.
2. I use high-tech rosin core silver-bearing solder from Radioshack with diameter 0.022″ ( Catalog #: 64-013 ). I think standard rosin core solder will work just fine.
3. Desoldering pump for removing solder around component leads. I use Edsyn Soldapullt pump, model DS 017.
4. 99% isopropyl alcohol and tooth brush for cleaning the motherboard from flux.
5. A new DC power jack.

Laptop DC power jack repair guide.


As you see on the following picture, the solder drop on the positive terminal looks different than on other three contacts. That’s where the problem is. The positive pin is not making a good contact with the motherboard and because of that power to the laptop cuts off when I move the power plug inside the power jack.
I’m going to desolder the power jack from the motherboard, clean contacts on both power jack and motherboard and then solder it back in place – this is the proper way fixing the power problem.

Start desoldering process with adding some new fresh solder to all three contacts. This will make old solder more flowable, easier to remove.

While heating one of the contacts, remove the solder from this contact using the desoldering pump. Repeat the same steps with all power jack contacts until you remove as much solder as possible.

Grab the power jack and carefully try removing it from the motherboard. Most likely you will not be able to remove the power jack the first time because there will be some solder bridges left between the contacts and traces on the motherboard. Carefully wiggle the power jack without applying any significant force and at the same time heat up all contacts one by one. This will help you to remove the power jack.

The DC power jack is almost removed from the motherboard.
Be careful. Inside the positive hole there is a copper sleeve which connects the terminal on one side of the motherboard with the traces on the other side. If you are removing the power jack with force, you can pull the sleeve from the hole. You don’t want to do that.
UPDATE: If you accidentally removed the internal sleeve, check out this post: How to fortify damaged power jack connection.
So, do not apply any force and make sure the solder is melted when you are removing the power jack. I hope you understand what I’m talking about.

After the power jack is removed, clean all oxidized contacts with a knife.

Apply a fresh coat of solder to all contacts on the power jack.

The power jack terminals will look dirty because of melted flux.

You can remove the flux using the tooth brush and alcohol. It’s not necessary but it will make your job looking clean.

Apply a fresh coat of solder to all power jack terminals on both sides of the motherboard.

This side has been coated.

And this side has been coated too.

Now you can install the power jack back on the motherboard. Put something under power jack so there is no gap between the jack and the motherboard. Now you are ready to solder the jack back in place.

Solder all power jack pins.

The job is done and the laptop DC power jack is fixed. B-E-A-utiful!
Now just install the motherboard back into the laptop and you are done.