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 A+ Essentials (220-801) Cram Notes


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3.2 Compare and contrast the components within the display of a laptop

1. 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.

2. Most laptop computers require a function key or software command to activate/deactivate the laptop video output signal. Usually, the activation/deactivation command acts as a toggle switch: repeat the command to display the image on the internal laptop display, the external display (projector) or both displays simultaneously. Examples: Acer: Fn+F5, Dell: Fn+F8 will activate/deactivate laptop/external display.

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

4. 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.

5. 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.

6. 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.

7. Laptop computer screens are equipped with a "Function" key as well as numerous hot keys for fast adjustments of various features on the computer, such as increasing or decreasing the brightness of the laptop screen. Dimming the screen is desirable when working in direct sunlight or to create a more soothing display that's easier on the eyes. The precise key sequence varies on different laptop models, but involves a combination of the function and arrow keys.

a. Press the Function ("Fn") key on the laptop keyboard and continue holding it down. This key is usually on the lower, left side of the keyboard.

b. Press and release the left arrow key to dim the laptop screen one increment, or hold the key to dim the screen as low as it will go. The arrow key may also be printed with a sunburst icon. Alternatively, on some laptops press one of the numbered F keys on the top row to dim the screen. The correct key will usually be printed with a filled-in sunburst icon, while the F key to brighten the screen will have a hollow sunburst icon.

c. Press the right arrow key to brighten the screen or use the numbered F key at the top of the screen

8. Plasma display panels consume most power because of the inherent architecture of the Plasma panels. On the other hand, OLED displays, which have recently come to market, consumes least power.

9. A disk enclosure is essentially a specialized chassis designed to hold and power disk drives while providing a mechanism to allow them to communicate to one or more separate computers. Drive enclosures provide power to the drives therein and convert the data sent across their native data bus into a format usable by an external connection on the computer to which it is connected. Note that a S CSI adaptor will not solve the problem as it would not supply the power and other signals that may be necessary to proper functioning of the hard drive.

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