CompTIA®A+ Exam Notes : Laptop Hardware And Companents

3. Mobile Devices

3.1 Laptop hardware and components

Hard drives: Laptop hard drives commonly have a 21/2" form factor. The most common form factor for desktop hard drives is 31/2". Laptop hard drives use the same drive technologies as their desktop counterparts, such as serial and parallel ATA. As with desktop hard drives, laptop hard drives are available in both solid-state and conventional varieties. Unlike desktop hard drives, laptop hard drives do not have separate power connectors. Some features are given below.

1. 2.5" drives are more readily available than the 1.8 and a whole lot less expensive. Plus the vast majority of laptops take 2.5 drives. The 1.8 drives are found in some of the 10 inch display laptops.

2. Ultraportable laptops use 1.8" drives because they weigh less and consume less power. However, they suffer from slow rotation speed and access time. 2.5" drives are much better performance wise because they have larger caches and higher rotation speeds.

Displays: LCD screens require a backlight system to operate, there are two backlight systems in use today:

a. CCFL - Cold Cathode Fluorescent Light, is an older backlight method, which utilizes a daylight specter fluorescent tube and an inverter which powers it.

b. LED - is a backlighting system which does not use an inverter, and instead of a fluorescent tube it uses a strip of LEDs (Light Emitting Diodes).

So in essence there are two types of laptop screens: LCD-CCFL and LCD-LED: these screens are not interchangeable.

LEDs do not require backlighting like LCDs. LCDs work by selectively blocking areas of the backlight to make the images that you see, while LEDs generate light themselves. Because LEDs do not require backlighting, they consume much less power than LCDs.

Plasma display panels consume most power because of the inherent architecture of the Plasma panels. On the other hand, LED displays consume least power relative to plasma and CCFL.

OLED(Organic Light Emitting Diode): OLED are thinner and lighter than other screen types, making them an excellent choice for handheld devices. OLEDs are designed with a layer of organic compounds sandwiched between two light-emitting electrodes. CRT monitors are big, bulky, and use a cathode ray tube. Plasma displays, popular in home big-screen TV systems are made of small cells of ionized gas and provide excellent contrast ratio. LCDs use liquid crystal displays and are frequently used in laptop computers.

WiFi antenna connector/placement: The wireless antenna is located in the display. While replacing a laptop screen you may encounter number of wires coming from the screen to the laptop body. One of these is the cable that connects the wireless antenna with the wireless card located in the body of the laptop. The antenna built into the display usually work quite well. In any specific situation improve the signal by moving the laptop around. This changes the polarization of the antenna and may cause it to line up better to the incoming signal.

Webcam: Many displays today, especially laptop displays, have a webcam built in. They come ready to go with all drivers preinstalled and nothing to configure or set up. To replace the webcam disconnect the laptop lid from the base,remove the screw covers ans screws holding the display bezel in place, and remove the bezel. After removing the screws holding the mounting rails to the hinges, remove the LED screen from the lid assembly.

Microphone: While many desktop systems lack a built-in microphone, almost all laptops have one. In some cases this microphone will be located on the laptop bottom, but in many cases it will be in the display next to the webcam or off to the side. If you need to replace it, you will need to take the same steps to get inside the display that you done for the webcam.

When you unhook the lid from the bottom, you will need to unplug several things from the board, nd one of those will be the microphone cable. If microphone is not working inspect the cable ,sometimes cable can be cut by the constant opening and closing of the case. You may be able to repair the cable without replacing the microphone.

Inverter: An inverter is a component that takes DC power and converts it to an AC form that can be used by the LCD screen. It is implemented as a circuit board that is located behind the LCD. If the inverter needs to be replaced,you should be aware that it may contain stored energy, so it may need to be discharged to be safe.

Digitizer/touchscreen: Digitizer read pressure applied to the surface of the display and are what make touch-screens work. In some cases, they work with a stylus or small pen-like device , in others you key to activate them. If these keys are not present, consult the documentation for the key to use in conjuction with Fn to increase and decrease brightness.

Common problems with laptop displays:

1. Display not working: If the external display is working properly and the problem is only with the internal laptop display, the most likely problem is with the inverter which powers the LCD display. Some times, an outline of an image can be viewed on a laptop screen, but it is very dim and the screen appears almost black. Such problems are almost always due to bad inverter and LCD.

2. Dead pixel: Dead pixel usually requires replacement of the LCD screen, and it is very expensive. If the laptop is new, check with your manufacturer for warranty replacement.

3. The inverter board is responsible for converting low voltage DC power to high voltage AC, necessary to light up the backlight bulb. If the inverter board is bad, the LCD screen (backlight bulb) will not light up when you turn on the laptop, but you still should be able to see a very dim image on the screen. Most commonly (say 80% of the time) it's the inverter, 10% it's the ccfl tube in the LCD panel, and 10% it's the motherboard or the VGA cable.

4. Digital displays offer best quality when operated at native resolution.

5. A dim screen can be caused by four things:

  • The LCD inverter which causes the LCD panel to light up

  • The CCFL fluro tube in the LCD panel

  • The motherboard supplying signal & voltage to the inverter

  • A damaged video cable between the laptop and the screen e. An LCD-LED display uses backlight and not a CCFL bulb. Therefore, the problem is most likey with backlight failure.

Internet connectivity problems: Laptops, being mobile, usually participate on more than one network, and often use a static IP address at one location and a dynamically assigned IP address at another. For example, your computer might use dynamic addressing (DHCP) at the office but need to use a static IP address when at home to connect to a broadband ISP. This often results in connectivity problems. Windows XP Professional solves this problem by allowing the user to configure the computer to first try DHCP, and then, if the attempt fails, to try alternate static IP address settings.

Bluetooth connectivity problem: Laptops with wireless networking capabilities usually provide a shortcut key to enable and disable the wireless radio. This feature is usually accessed by using a key combination of the function (Fn) key and one of the F keys at the top of the keyboard. Sometimes this key can also activate and deactivate the Bluetooth function of your computer.

How to replace the laptop battery

1. Turn off your laptop and disconnect the AC adapter.

2. Release the latch or other attachment devices that hold your battery in place.

3. Slide the old battery out of its compartment or storage bay.

4. Take the replacement battery out of the box.

5. Slide it into the notch or bay.

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