CH10 PPT CompTIAA PowerSupplies

Mike Meyers’ CompTIA A+®
Guide to

Managing and
Troubleshooting PCs
Fourth Edition

Power Supplies
Chapter 10

© 2012 The McGraw-Hill Companies, Inc. All rights reserved

Mike Meyers’ CompTIA A+®
Guide to

Managing and
Troubleshooting PCs

Overview

Fourth Edition

• In this chapter, you will learn how to
– Explain the basics of electricity
– Describe the details about powering the PC
– Install and maintain power supplies
– Understand power-supply troubleshooting and fire safety © 2012 The McGraw-Hill Companies, Inc. All rights reserved

Mike Meyers’ CompTIA A+®
Guide to

Managing and
Troubleshooting PCs
Fourth Edition

Understanding Electricity

Figure 1: Typical power supply mounted inside the PC system unit

© 2012 The McGraw-Hill Companies, Inc. All rights reserved

Mike Meyers’ CompTIA A+®
Guide to

Managing and
Troubleshooting PCs

Measuring Electricity

Fourth Edition

• Voltage—pressure of electrons in a wire

– Unit of measurement: volts (V)
• Current— flow (or amount) of electrons in a wire

– Unit of measurement: ampere (A)
– When voltage is applied to a wire, electrons flow, producing current
• Wattage—measure of power consumed or needed

– Unit of measurement: watt (W) W = V * A
• Resistance—impedance or opposition to the flow

– Unit of measurement: ohm (Ω)
© 2012 The McGraw-Hill Companies, Inc. All rights reserved

Mike Meyers’ CompTIA A+®
Guide to

Managing and
Troubleshooting PCs

Measuring Electricity (continued)

Fourth Edition

• Wire has amperage rating
– Defines how much amperage it can handle
• i.e., 20 amp, 30 amp

– If you exceed amperage
• Wires heat up—may break

• Circuit breakers are heat sensitive
– Sense when amperage exceeds threshold
– Breaks the circuit to stop the flow of electricity

© 2012 The McGraw-Hill Companies, Inc. All rights reserved

Mike Meyers’ CompTIA A+®
Guide to

Managing and
Troubleshooting PCs

Two Types of Current

Fourth Edition

• Alternating current (AC)— electrical current flows in both directions –