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 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.

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: 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: a. The LCD inverter which causes the LCD panel to light up b. The CCFL fluro tube in the LCD panel c. The motherboard supplying signal & voltage to the inverter d. 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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