COMPUTER ENGINEERING

BYKAYODE BACTI

AC/DC power adapter as known as power supply or power brick converts the high voltage AC power from a wall outlet into the low voltage DC power needed for your laptop.The AC/DC adapter provides power for the laptop and charges the battery. It’s very important to use the right adapter for your laptop.

If you are looking for a new adapter, you should check the following:1. Your new adapter must have exactly the same plug (adapter tip) as the original one.2. Your new adapter must output exactly the same voltage as the original one.3. Polarity on the new adapter’s plug must be the same as on the original one.You can find the output voltage and amperage on the adapter’s label. As you see on the picture below, my adapter outputs 19V-3.42A.

When you buy a new adapter, you can follow this rule:The output voltage must be the same, the amperage could be the same or higher than on the original power adapter.

HOW TO TEST OR REPAIR POWER ADAPTERS.Most newer laptop power adapters are sealed and you cannot repair them. If the adapter is dead, you’ll have to buy a new one.1. How can you tell if the AC adapter is dead? You can test it with a voltmeter. On the picture below I’m testing a 15V adapter and as you see the output is 15.45V. It’s pretty normal and there is nothing wrong if the output voltage is a little bit higher but if you are getting 0V, the adapter is definitely bad.

MAIN BATTERY

Any laptop computer has a battery pack which provides power to the laptop while it’s not connected to the wall-plug through AC/DC power adapter. Laptop batteries come in many different shapes and they are model-specific.The laptop battery life depends upon many conditions and circumstances: screen brightness, intensity of running programs, the temperature of the working environment, etc…

Any laptop computer has a battery pack which provides power to the laptop while it’s not connected to the wall-plug through AC/DC power adapter. Laptop batteries come in many different

shapes and they are model-specific.

TROUBLESHOOTING LAPTOP BATTERY PROBLEMS.Let’s say your laptop stopped running on the battery power. It works fine from the AC adapter but shuts down as soon as you unplug the adapter. If that’s the case, try reconnecting the main battery. Remove it from the laptop and install back. It’s possible the battery is not making good connection with the motherboard.

The laptop battery life depends upon many conditions and circumstances: screen brightness, intensity of running programs, the temperature of the working environment, etc…The same battery could last longer in the same laptop if you optimize the power usage settings in the control panel. You can lower screen brightness, reduce CPU processing speed, chance cooling method, and other settings available on your laptop. Some of these settings could be changed only through the manufacturer’s power management software.

Unfortunately, the only reliable way to test the main battery is replacing it with another known good battery.If the laptop cannot detect the battery, even though it’s installed, try replacing the battery with a new one. If you still have the same issue, most likely there is a problem wiht the system board.

SYSTEM BOARD

A system board also known as motherboard or mainboard is the main circtuit board in any laptop. Unlike desktop PC system boards, laptop system boards come in thousands of different shapes and sizes. Laptop motherboards are model-specific. In other words, you cannot remove motherboard from a Toshiba laptop and stick it into a Dell laptop. All parts inside a laptop are connected to the system board, either directly via a connector mounted on the system board or through a cable.

• In a typical laptop the following ports and components are permanently attached to the system board and cannot be easily removed and replaced without 1. Hard drive (.3. Memory (Rslots.4. Batteryphone) jacks.7. Volume control wheel.8. USB ports.9. Eithernet (RJ45 aka network) port.10. IEEE 1394 (Fire Wire) ports.11. Video chip and some other components and ports.

System board, processor (CPU) and LCD screen are the most expensive parts in any laptop. In some cases, when one of these three parts fails, it’s cheaper to buy a brand new laptop than replace the failed part. But each case is different so do your research.SYSTEM BOARD FAILURE SYMPTOMS.When a system board fails, you may experience the following most common problems with your laptop. 1. The laptop is completely dead. There are no LED light activity when you press on the power button or plug in a known good AC power adapter. 2. The laptop starts but the video output on the LCD screen or external monitor is garbled. Most likely this is related to the VGA chip failure. 3. The laptop turns on without video on the screen and the power LED starts flashing. 4. The laptop works fine with AC power adapter but will not charge a known good battery. If that’s the case, most likely there is something wrong with the battery charging circuit or DC power jack.

CMOS battery also know as RTC batteryAny laptop computer has a CMOS battery also known as RTC battery. The CMOS battery connects directly to the laptop system board and helps to retain important BIOS settings such as system time, date, BIOS configuration while the laptop is turned off or even when the main battery is removed.The CMOS battery is rechargeable and it’s getting charged when the laptop is plugged into the mains.CMOS batteries come in different shapes and sizes.On the picture below you see a basic coin cell CMOS battery. This type of batteries usually found in older laptops. This battery is removable and replaceable.

Here’s another type of CMOS battery. Basically, it’s two coin cell batteries but they are bundled together and have a cable which plugs into the system board. This battery is removable and replaceable.

On the next picture you see a CMOS battery which is soldered to the system board. In order to replace this type of battery, you’ll have to unsolder it from the system board.

CMOS BATTERY LOCATION IN A LAPTOP.In some laptops the CMOS battery could be easily accessed from the bottom, as it shown on the picture below. As an example I took a Dell Inspiron 1720.

In some laptops the CMOS battery is hidden under the keyboard. As an example I took a HP Compaq nc6400 laptop.

Here’s the worst case scenario. The CMOS battery is hidden under the laptop cover. In order to access and replace the battery you’ll have to disassemble

the whole laptop. As an example I took a Toshiba Satellite A305 laptop.

CMOS BATTERY RELATED PROBLEMS.Here’s the most common problem related to the CMOS battery.Each time you turn off the laptop it resets date and time back to factory defaults. When you turn the laptop back on it asks you to set date and time. If that’s the case, most likely your CMOS battery is old and has to be replaced.By the way, removing the CMOS battery on most newer laptops will not clear the BIOS password

KEYBOARD

In laptops, a keyboard is the main input device. It’s interface between a user and a laptop.In most laptops the keyboard is connected directly to the motherboard via a flat ribbon cable.KEYBOARD REMOVAL STEPS.In most laptops you can remove the keyboard as it explained in the following three steps

Disconnect the keyboard cable from the motherboard and remove the keyboard

KEYBOARD RELATED PROBLEMS.1. Here’s a very common “keyboard related problem”. When you press on keys U, I, O, J, K, L, M the keyboard types 4, 5, 6, 1, 2, 3, 0. It happens because the “Number Lock” function is enabled. You can turn this function off via a shortcut on the keyboard. Hold down the Fn key and at the same time press once on the NumLk key.2. One or more keyboard keys came off. You can install these keys back on the keyboard, you’ll find lots of instructions on the internet or YouTube how to do that.3. When you press on one key it types two letters. For example, you press on W but it types WE, you press on T and it types TY, etc… Most likely this problem is related to the keyboard and it has to be replaced.4. Some keys in horizontal or diagonal row stopped working at all. Again, most likely there is a problem with the keyboard and it has to be replaced.ATTENTION! If you still have the same issue after replacing the keyboard, there could be a problem with the keyboard controller on the motherboard. It means the whole motherboard has to be replaced.A laptop keyboard is not repairable. If it stopped working, you have to replace the whole unit.

Processor also as CPU

A processor also known as CPU (Central Processing Unit) is the brain of a laptop computer. The processor is one of the main components in a laptop. Laptop processors are made mainly by Intel and AMD.The processor connects directly to the system board via a processor socket aka CPU socket as it shown on the picture below.

QUESTIONS AND ANSWERS.Question: Can I overclock the CPU in my laptop?Answer: No, you cannot. In most laptops the BIOS doesn’t give you this option.Question: Can I upgrade the CPU in my laptop?Answer: Unfortunately, laptop manufacturer’s do not provide this information to general public. Yes, it’s possible on some laptops. You’ll have to find a new CPU which fits the same socket and try it.Question: Are CPU failures very common?Answer: No, they are not. CPUs fail rarely. If your laptop stopped booting, the CPU will be the last component to blame. Check the memory and motherboard first.

COOLING FAN

A CPU cooling fan is a dedicated fan which cools down the heatsink and eventually the CPU (Processor). Usually the CPU cooling fan comes as a part of the heatsink assembly – a metal part drawing heat from the CPU chip. In addition to the CPU cooling fan, some laptops have a dedicated GPU (graphics processing unit) fan which cools down the GPU chip.The CPU and GPU cooling fans connect directly to the motherboard via a cable running from the fan. When CPU and GPU chips get hotter, the cooling fan spins faster.

If you cannot find it on the bottom, then it’s buried inside the case, as on the following Dell laptop.

COOLING FAN RELATED PROBLEMS.If your laptop feels very hot and shuts down without any warning, it’s possible that you have a faulty fan. Listen for the fan. Is it working? Sometimes you can see the fan through the fan grill on the bottom of the laptop. Can you see the fan spinning?If the fan never starts, probably it is bad and has to be replaced.When the fan bearing goes bad, the fan starts making grinding noise. In this case you’ll have to replace the fan.If your CPU fan works hard all the time, most likely it happens because the heatsink is dirty and is clogged with dust and lint. You can clean the heatsink using compressed air.

Memory also known as RAM

A laptop memory also know as RAM (Random-access memory) is a temporary data storage. It’s a volatile type of memory. When you turn off the laptop, all the information stored in a RAM module is lost.More memory installed into your laptop gives you a better (faster) performance.You can test laptop memory with a free diagnostic tool called Memtest86+.A type of memory used in laptop computers called SO-DIMM (Small Outline Dual In-line Memory Module).

SDRAM SO-DIMMHere are three most common memory types found in laptop computers:1. SDRAM SO-DIMM memory has 144pins.PC100 modules running at 100MHz.PC133 modules running at 133MHz.PC133 modules are backward compatible with PC100 modules.If your laptop requires a PC100 memory module, you can safely use a PC133 module but it will run at PC100 speed.

DDR SO-DIMM memory2. DDR SO-DIMM memory has 200 pins. PC2100 (DDR266) modules running at 266MHz.PC2700 (DDR333) modules running at 333MHz.PC2700 memory is backward compatible with PC2100 memory. If your laptop requires a PC2100 module, you can safely use a PC2700 module but it will run at PC2100 speed.DDR memroy modules are not backward compatible with SDRAM modules.

DDR2 SO-DIMM3. DDR2 SO-DIMM memory has 200 pins. PC2-3200 (DDR2-400) running at 200MHz.PC2-4200 (DDR2-533) running at 266MHz.PC2-5300 (DDR2-667) running at 333MHz.PC2-6400 (DDR2-800) running at 400MHz.Faster DDR2 memory modules are backward compatible with slower DDR2 memory modules. For example, if your laptop requires a PC2-4200 memory module you can safely use a PC2-5300 module but it will run at PC2-4200 speed.DDR2 memory modules are not backward compatible with DDR modules. The notch on DDR2 is located in a different position from DDR.

WHERE MEMORY MODULES ARE LOCATED.In a laptop computer memory slots could be found in a few different locations, it depends on the brand and model of the laptop.1. Both memory slots can be accessed from the door on the bottom.2. One slot is located on the bottom and another one under the keyboard.3. Both memory slots are located under the keyboard.4. There is only one memory slot available for upgrades. The main memory is integrated into the motherboard.

HOW TO REMOVE MEMORY MODULE FROM THE SLOT.Step1.Release latches on both sides from the memory module with your fingers.

Step2.The memory module will pop up at a 20-30 degree angle.

WHAT YOU NEED TO KNOW BEFORE BUYING LAPTOP MEMORY.1. You are looking for SO-DIMM memory used in laptop computers.2. Type of the memory used in your laptop: SDRAM, DDR, or DDR2.3. How many memory slot are available.4. How much memory your laptop can handle.

Hard drive

Most modern laptops use 2.5″ hard drives. Older laptops use IDE hard drives, newer laptops use SATA hard drives. SATA and IDE drives are not interchangeable, they have absolutely different connectors.

If your laptop came with an IDE hard drive you cannot replace it with a SATA drive. The connector on your drive will not mach connector on the motherboard.As you see on the pictuer above, a SATA drive has two flat connectors and an IDE drive has two rows of pins.

SATA hard drives has faster data transfer rate then IDE drivers. SATA – 150MB/s and IDE – 100/133MB/s.

Laptop hard drives spin at different speeds and most common are 4200RPM, 5400RPM, 7200RPM.

The RPM number indicates how fast the hard drive platters spin. Hard drives with high RPM number are quicker than hard drives with low RPM number because they can access data faster.

SATA connectors on a laptop hard drive are similar to SATA connectors on a desktop hard drive. You can connect a SATA laptop hard drive to a desktop computer using same SATA cables.

WHERE HARD DRIVE IS LOCATED IN A LAPTOP.On most laptops the hard drive can be accessed from the bottom

On some laptops the hard drive is buried inside the case and it’s necessary to disassemble the laptop in order to access and replace the hard drive.

HARD DRIVE UPGRADE.A hard drive is the slowest part in any laptop. If you would like to speed up your laptop, replace your low RPM drive with a faster one. Fast RPM drives are backward compatible with low RPM drives.If you would like to install a larger hard drive, take a look at the user’s manual and laptop specifications. Make sure your laptop supports larger drives

Graphics card aka video board

A graphics card also known as a video card or VGA board is a laptop component responsible for creating images on a laptop screen.In most low-mid range laptops the graphics card is integrated into the motherboard. In other words, it’s a part of the motherboard. If that’s the case, the graphics card is not removable or upgradeable. If the graphics card fails, you have to replace the whole motherboard.A discrete graphics card can be found in high range models and high end gaming laptops. Discrete graphics cards can be removed and in some cases they are upgradeable.Here’s another example of the discrete video card in a high end gaming laptop. As you see the video card can be separated from the motherboard.

GRAPHICS CARD RELATED PROBLEMSYou can use the following method for troubleshooting problems related to graphics cards.Let’s say your display stopped working properly. The image is distorted or garbled. Is this problem related to the VGA board or LCD screen?Connect your laptop to an external monitor and take a look at the external video output. If you see the same problem as on the internal LCD screen, most likely it’s related to the VGA board. If video on the external monitor works fine and the problem appears only on the internal LCD screen, most likely your problem is related to the LCD screen or LCD cable.

TYPICAL VIDEO CARD FAILUREBelow you can see a few pictures taken from a laptop with a faulty video card.1. When you start the laptop, the initial screen with manufacturer’s logo is not displayed properly on both internal LCD screen and external monitors. You can see random characters, vertical lines running through the logo, random colors, etc…

2. Same problem appears when the laptop displays the boot menu. The screen is either not readable at all, or there are some random characters all over the image.

3. Finally, the laptop starts loading Windows, but the image on both screens is still garbled.

CD/DVD-RW optical drive

Most modern laptops are equipped with a CD/DVD-RW drive also known as an optical disc drive which allows it to read and write data from or to a CD/DVD disc. All laptop CD/DVD drives are shaped the same but they all have different face plates also know as front bezels. On the picture above you can see three different laptop CD/DVD drives with different face plates/front bezels.

When you are replacing a failed CD/DVD drive, you have to make sure that the face plate from the old drive will fit your new drive.On the picture below you can see two different types of connectors found in modern CD/DVD optical disc drives. One drive has a SATA connector and the other one has an older slim ATAPI connector.

An optical disc drive with a SATA connector is not interchangeable with an optical disc drive with a slim ATAPI connector and vice versa. In other words, if your laptop motherboard comes with a SATA connector for the optical drive, you can only use CD/DVD drives with SATA connectors.

On the next picture I compare a SATA connector used in laptop hard drives with a SATA connector used in CD/DVD drives. As you see, these two connectors are a little bit different. The data connector (right connector) is shaped similarly for both drives, but the power connector (left connector) is shaped differently.By the way, you can connect a 2.5″ laptop SATA hard drive to a desktop computer using same cables as you use for a regular 3.5″ desktop hard drive.

In order to connect a Slimline SATA optical CD/DVD drive to a desktop computer, you’ll have to purchase the Slimline SATA Cable.

If you are replacing the CD/DVD disc drive in your laptop with a new one, make sure your new drive is compatible with the laptop. The best way to find a new optical disc drive is searching by the manufacturer’s part number found on the old drive.

When you install an optical drive which is not compatible with your laptop, it will not be recognized by the BIOS or you’ll get an IDE #1 ERROR on start up.

HOW TO REMOVE CD/DVD DISC DRIVEIn most laptops, the CD/DVD disc drive is secured by one or two screws on the bottom of the laptops. Remove these screws and pull the optical disc drive from the laptop.

On some other models, the optical drive is secured by one or two screws located under the keyboard. If that’s the case, you’ll have to remove the keyboard first. After that remove those screws and pull the drive from the laptop

Audio board also known as sound board

In most laptops the audio board also know as sound board is integrated into the motherboard. In other words, it’s a part of the motherboard and cannot be removed or replaced separately.

Why the audio board cannot be removed? Because the audio chip is soldered to the motherboard.

If the audio board fails, you’ll have to replace the whole motherboard.AUDIO BOARD FAILURE SYMPTOMS AND TROUBLESHOOTING TIPS.1. There is no sound from internal speakers or headphones.Make sure the volume level is not set to minimum.Make sure the volume is not muted.If the volume is not mutes and volume level is not set to minimum, but you still have no sound, try reinstalling the audio driver.If reinstalling the audio driver doesn’t help, try reinstalling the operating system.If nothing helps, it’s possible you have a problem with the audio board.2. Headphones are working fine but there is no sound coming from the laptop speakers.Sometimes contacts inside the audio jack get stuck and there is no external sound because of that. Try to plug and unplug the headphone connector into the jack very quickly a few times.

Wireless card

Laptop internal wireless network cards also know as WLAN card or Wi-Fi card come in different shapes ans sizes. On the picture above you see two most common internal wireless card types found in laptops.Two wireless cards on the top have Mini PCI form factor connector and found mostly in older laptops.Two wireless cards on the bottom have Mini PCI-E (Mini PCI Express) form factor connector and found mostly in newer laptops.

Mini PCI-E connector is not backward compatible with Mini PCI connector. In other words, you cannot install a Mini PCI-E wireless card into the Mini PCI slot.The wireless card plugs into the Mini PCI or Mini PCI-E slot on the motherboard. Most internal cards have two small connectors for wireless antenna cables, some newer Mini PCI-E cards have three connectors and require three antenna cables.On the picture below you see an internal Mini PCI wireless card connected to the laptop. As you see, there are two antenna cables connected to the card. One main antenna cable and one auxiliary antenna cables.

In order to remove the wireless card, you’ll have to disconnect the antenna cables first. Grab firmly the antenna connector with your fingers and unsnap it from the card. Do the same with the second antenna cable. After that you remove the wireless card the same way as you remove the RAM module.1. Spread latches on both sides of the card with your fingers and the card will pop up at a 20-30 degree angle.2. Carefully pull the wireless card from the slot.On the picture below you see a newer Mini PCI-E wireless card pluged into the slot on the motherboard. In my example the card has three antenna cables. Many Mini PCI-E cards have only two antenna cables.This card connects to the motherboard differently than a Mini PCI card. Ther are no latches on the sides. The card is secured to the motherboard by two screws

In order to remove this card:1. Disconnect all antenna cables from the card. Do not forget to make a note how cables are connected.2. Remove two screws and the card will pop up at a 20-30 degree angle.3. Carefully pull the wireless card from the slot.On some laptops the internal wireless card could be accessed throught the hatch on the bottom, on other laptops it’s hidden under the keyboard or laptop cover.

LCD screen

The laptop screen mounts inside the laptop display panel between the screen bezel and display cover. The screen is attached to the screen brackets (display brackets) which are permanently attached to the display hinges.

A laptop screen also known as LCD screen displays an image generated by the laptop video card. The LCD screen receives data signal from the video card through the LCD cable.Laptop screens come in many different sizes and resolutions. In order to find the LCD screen size (in inches), you’ll have to measure the screen between the two diagonal corners.Older laptops had mostly full screen LCD displays. Newer laptops have mostly widescreen LCD displays.A backlight lamp (also known as CCFL bulb) is the main source of light in any LCD screen. The backlight lamp powers up by the inverter board.

TYPICAL LCD SCREEN RELATED FAILURESOn the following images you’ll see some typical LCD screen related failures.1. You can see image only on a part of the LCD screen. For example, only the top side of the screen works properly.

BUYING A NEW REPLACEMENT SCREENThe LCD screen is one of the most expensive parts in a laptop computer. If your screen is damaged and you decide to replace it yourself, you’ll have to make sure to purchase a new screen compatible with your laptop. Hear are a few things to consider before buying a new screen:1. Screen size.2. Some laptops come with full size LCDs. Some laptops come with widescreen LCDs.3. LCD screen could be matte or glossy.4. Same size LCD screens may have different resolutions.The best way to find a new replacement screen would be using the manufacturer’s part number or LCD screen model. Both could be found on the back side of the screen.

Screen inverter board

Laptop inverter boards (also know as LCD inverter, FL inverter, screen inverter, backlight inverter) come in different shapes and sizes. On the picture above you see some typical looking inverter boards found in laptop computers.The inverter board works as a power supply for the backlight lamp mounted inside the LCD screen. The inverter board converts low voltage DC power (few volts) supplied by the motherboard to high voltage AC power (few hundred volts) needed for the backlight lamp.

When the inverter board works properly, the backlight lamp gets power and the LCD screen lights up. As a result, the image on the screen is bright.

HOW INVERTER CONNECTED TO LDC SCREENOn the picture below you can see a typical laptop display assembly which includes the LCD screen, video cable and inverter board.One side of the inverter board connects to the backlight lamp and another side to the video cable (LCD screen cable).

HOW INVERTER MOUNTED INSIDE LAPTOP DISPLAY PANELIn most laptops the inverter board is mounted below the LCD screen as it shown on the picture below. You can get an access to the inverter board when you remove the screen bezel – a plastic frame around the LCD screen.

TYPICAL INVERTER FAILURE SYMPTOMSUsually inverters fail in one of the following ways:1. When you turn on the laptop, the screen lights up for a short period of time and then goes dark. You still can see an image but it is very dark, almost invisible and definitely not usable. When you restart the laptop, the screen lights up and then goes dark again. The laptop works fine with an external monitor.2. Your laptop turns on but the screen remains dark all the time. You still can see a very dim image outline. The laptop works fine with an external monitor.3. The laptop screen works fine for hours or even days, but sometimes it goes very dark as it mentioned above. When you restart the laptop, the screen works fine again.Inverter failure symptoms are very similar to backlight lamp failure symptoms and in most cases you cannot tell which one is causing the problem until you replace either the inverter board or the backlight lamp. From my personal experience, inverter boards fail more often than backlight lamps. If you have to guess, replace the inverter first.

LCD screen cable

A laptop LCD cable also known as video cable, display cable or screen cable. This cable transfers data signal from the motherboard and video card to the LCD screen. Also, most video cables supply high voltage DC power to the screen inverter.

On the picture you can see a typical laptop video cable. The cable has three ends with three connectors. One end plugs into the connector on the back of the LCD screen, the second end plugs into the inverter board, the third end plugs into the connector on the motherboard or video card.The top part of the cable runs inside the laptop display panel between the LCD screen and display cover.

The bottom part of the cable could be found either under the keyboard or keyboard bezel.

In order to remove and replace the LCD cable, it will be necessary to disassemble the whole laptop.LCD CABLE RELATED PROBLEMS1. The image on the screen appears normal until you move the display up or down. When you move the display, the images on the entire screen starts to flicker, disappear or change collors. As soon as you stop moving the display, the image gets back to normal.2. The LCD screen lights up but there is no image at all. The entire screen is blank. An external monitor connected to the laptop VGA port works fine, there is no problems with the external video output at all.3. Image on the entire LCD screen is garbled. An external monitor works fine.In many cases the video cable failures are very similar to the LCD screen failures.

Display hinges

HINGE RELATED PROBLEMS1. The laptop display feels loose. It will stay in the up position, but when you move the display it feels floppy.First of all, try tightening screws securing both hinges to the laptop base and display cover. If tightening screws doesn’t help, apparently your hinges are worn out and will have to be replaced soon.2. The display will not stat in the up position. When you open the display and leave it in the up position, it falls back.Most likely one or both hinges are broken and have to be replaced. Even if only one hinge is broken, I would recomment replacing both hinges because the second one is worn out and could break too in the near future.

Display hinges connect two halves of a laptop – the display panel and base assembly. All regular laptops have two hinges located on the left and right sides of the display panel. Tablet PCs have one hinge-swivel located in the middle of the display.The LCD screen mounts to the the screen mounting brackets which are permanently attached to the display hinges. There are two or more screws securing the LCD screen to each mounting bracket.The display hinges are not repairable. If the hinge is broken or too loose to keep the display in an open position, you have to replace it with a new one.

Screen backlight lamp

A backlight lamp (also know as backlight bulb, screen backlight, CCFL tube or bulb) is the main and only source of light in a laptop LCD screen. A typical laptop LCD screen has only one backlight lamp installed. The backlight lamp mounts inside the laptop screen in the lower part of the screen as it outlined on the picture above.A pair of cables with one connector coming from the screen plugs into the screen inverter board.The backlight lamp receives high voltage AC power from the screen inverter board which receives low voltage DC power from the motherboard via the LCD screen cable as it shown on the picture below

On the next picture you see a typical backlight lamp removed from a typical laptop LCD screen. There are two cables soldered to both sides of the backlight lamp attached to one connector.

BACKLIGHT LAMP REPLACEMENTIt is possible to replace a failed backlight lamp with a new one but it’s not easy because the backlight lamp is buried deep inside the LCD screen and it’s very easy to damage the screen during the disassembly process. This repair should be performed only by an experienced technician. You can find some home made backlight replacement instructions if you do Google search. For inexperienced people it would be much easier to replace the whole LCD screen

BACKLIGHT LAMP FAILURE SYMPTOMS1. The laptop screen lights up only for a short period of time or will not light up at all. The image on the screen is so dim that you can barely see it. At the same time, an external monitor attached to the laptop works fine.2. When you turn on the laptop, the screen works fine for a while, then start flickering and the light turns off. Again, there is a very faint image on the laptop screen and external video output works fine.3. The screen works but the image has a reddish/pink tone. External video output works fine.The backlight lamp failure symptoms are very similar to the inverter board failure symptoms. If you have to guess which one is causing the problem, try replacing the inverter board first.

Web camera also known as webcam

Most newer laptops come with a build-in web camera also known as webcam. The web camera is located on the top of the display panel. Some people think the web camera is a part of the LCD screen but it’s not. The web camera is a separate module which is mounted inside the display panel above the LCD screen.On the picture below you see a laptop display with removed bezel. The web camera module is glued to the display cover. The web camera is connected to the system board via a cable which plugs into the connector on the right side of the web camera board.

The web camera board and LCD screen are two separate modules and can be removed and replaced separately.WEB CAMERA RELATED PROBLEMS.Let’s say your web camera stopped working. You can see the camera detected in the device manager, but it will not work. What can you do? Try reinstalling the webcam driver and most likely the problem will be fixes.Here’s how you can reinstall the driver.Go to the device manager and find the webcam. It might be listed in USB devices. Right click on the webcam entry and uninstall the driver. Now restart the laptop. When it boots, the laptop will detect the webcam and install the driver. Does it work for you?