Study Lab

Don't miss the Study Lab materials found on the CD accompanying this book. Each Study Lab is tailored to the individual chapters in this book, meaning that you'll quickly be able to determine which topics you understand well enough to pass the exam and which topics need more study. The Study Labs are presented in printable PDF format so that you can take them with you to study at work, on the road, or even in your car just before test time!

The Absolute Minimum

Use this list of chapter highlights as a quick review just before the exam, and to help you find areas you need to study in greater detail.

• Power supplies are rated in watts.

• An overloaded power supply might reboot itself or overheat.

• A power supply set to the wrong voltage cannot start the system.

• Multiply amperage by volts for each power level used by a device to determine its total wattage use.

• Fan failure at startup is usually caused by incorrect input voltage or system shorts.

• The interior of a power supply has no user -serviceable components and contains potentially fatal voltage levels.

• Poor cable placement, missing slot covers, dirty case vents, and a lack of case fans are typical reasons for system overheating .

• You can add fans to the case, North Bridge chip, and to hard drive bays to improve airflow.

• Slimline, PS/2, and LPX are all names for the power supply used by most Baby-AT systems.

• Slimline power supplies have two six-pin connectors, which can be installed incorrectly, leading to system failure.

• ATX and SFX power supplies have a keyed 20-pin motherboard connector.

• SFX power supplies are available in two varieties: SFX-L and SFX-S, referring to the location of the AC power cord connection.

• Systems that use the Pentium 4 processor require an ATX-12V connector on the power supply.

• All types of power supplies have two four-wire power connectors: Molex (large connector for hard and optical drives and case fans, and floppy (small connector) for floppy drives and other low-power devices.

• A power supply is held in place by several mounting screws , which must be removed before the power supply can be removed.

• A multimeter can be used to test AC and DC voltage, cables (CONT), and ohms. Some also test amps (current).

• Parallel-mode tests use the multimeter running in parallel to the circuit (DC voltage), whereas series-mode tests (amperage) place the multimeter in the test circuit.

• To determine if a power supply is working correctly, you should test all voltage levels and Power Good.

• Improperly wired outlets, no ground to system, touching the interior of the power supply, and installing a standard power supply on a system designed for a Dell proprietary ATX power supply are all hazardous activities that should be avoided.

• True surge suppressors have a UL-1449 or IEEE-587A rating.

• A true UPS battery backup unit provides battery power to the system at all times.

• Most so-called UPS units are really SPS (standby power supply) units that start up only when AC power fails.

• For adequate runtimes , you should choose a UPS/SPS with a VA rating at least twice the VA of the devices you connect to it.

• Multiply watts by 1.4 or amps by 120 to get the VA rating.

• When troubleshooting power supplies, keep in mind that problems such as loose AC or power switch cables, short circuits, and loose add-on cards can cause system failure. Check these before testing the power supply.