Chapter 5 Review. Power Supplies

Transcription

1 Chapter 5 Review Power Supplies Name Period Date Score Write your answers in the spaces provided at the end of the question. For fill-in-the-blank questions, provide the word or words needed to complete the sentence. 1. A(n) sign indicates positive voltage, and a(n) sign indicates negative voltage. 2. Electrical current that flows in one steady direction is called and is represented by the letters. 3. Alternating current frequency is expressed in. 4. A multimeter is used to check,, and. 5. Electrical pressure is measured in. 6. Opposition to current flow is measured in. 7. In electronics notation, the letter A represents. 8. In electronics notation, the letter V represents. 9. In electronics notation, the symbol Ω (omega) represents. 10. The condition of having an uninterrupted path for current is known as. 11. A resistance value too high to measure accurately is called a reading of. 12. A wire with no opposition to current flow would have a resistance reading of. 13. Electrical power supplying a fuse must be before taking a resistance reading. 14. Electrical power is measured in. 15. The unit of watts is the product of multiplied by. 16. A good voltage reading will be plus or minus of the 120-volt rating. 17. A(n) is used to limit the amount of electrical energy that can pass through a power supply. Copyright by Goodheart-Willcox Co., Inc. Continued Permission granted to reproduce for educational use only Chapter 5 Power Supplies 95

2 Name 18. The maximum amount of electrical energy that can be connected to most power strips is watts. 19. On a multimeter, the red lead should be plugged into the jack that is marked as. 20. On a multimeter, the black lead should be plugged into the jack that is marked. 21. A good fuse will have a resistance reading of. 22. A(n) should be used to protect loss of data caused by a loss of electrical power. 23. An electrical circuit installed to only supply computer equipment is called a(n) circuit. 24. The large connector on a power supply is called a(n) connector, and the smaller power connector is often referred to as a(n) connector. 25. The power supply was designed to accommodate PCIe devices and power-hungry video cards. 26. The power supply connector has 20 pins and is known as a 2 10 connector. 27. The standby power connection is also referred to as. 28. The power management standard in which the BIOS controls the power management features is called. 29. The power management standard is enabled in the BIOS but controlled by the operating system. 30. List six things that may indicate a bad power supply. 31. Power strips that are designed to protect equipment against electrical surges have a(n) connected across the internal electrical line. 32. When replacing a power supply, the replacement unit watt rating should or the original power supply rating. 33. The charge on a(n) battery lasts longer than alkaline or nickel cadmium. 34. The chemical solution inside a battery is referred to as. 35. The biggest advantage of the battery is the lack of required maintenance compared to a lead-acid battery 96 Computer Service and Repair Instructor s Manual Copyright by Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational use only

3 For the A+ Certification exams, you should be able to name the common types of PC power supplies and identify their characteristics. You should also be able to select the appropriate power supply for an upgrade or replacement, identify preventive maintenance techniques related to power such as incorporating power strips, surge protectors, and battery backup units. You should be able to identify maintenance techniques related to proper PC cooling and ventilation. The use of the multi meter is also covered. Practice 5.1 Identify each of the following as direct current (dc) or alternating current (ac). 1. Series of cycles: 2. Battery: 3. Flows only in one direction: 4. Flows only from negative terminal to the positive terminal of a power source: 5. In a state of constant change: 6. Wall outlet: Practice 5.2 Fill in the blanks for the statements about the sine wave. Not all of the terms will be used. 1 6 frequency voltage level 3 cycle time A 1 B ----'» Copyright by Goodheart-Willcox Co., Inc. 31

4 1. Label A in the illustration indicates the of the ac 1. voltage. 2. Label B in the illustration indicates the of the ac 2. voltage. 3. The sine wave from point C to D in the illustration indicates 3. one 4. The number of cycles per second of alternating current is its The frequency of the ac voltage shown in the illustration is 5. Hz. Practice 5.3 Fill in the blanks for the statements about electrical energy. Not all of the terms will be used. amperes current power volts backfeed electrocution resistance watts continuity ohms voltage 1. When taking a resistance reading, a component should be removed from a circuit to prevent. 2. The amount of electrical pressure in a circuit or power source is 3. The ability of a device or component to allow an unobstructed flow of electrical energy is called. 4. The amount of electrical energy provided or used in a 4. circuit is called - 5. The amount of electron flow in a circuit is measured in Voltage is measured in Resistance is measured in Power is measured in Computer Service and Repair Study Guide Copyright by Goodheart-Willcox Co., Inc.

5 Practice 5.4 Determine the condition of the following switches. burned open good shorted Name Switch in OFF position A. ( OO.OJ Switch in ON position OF~ + B. ( 00.0,,) Switch in OFF position c. (])v n D. Switch in ON position Copyright by Goodheart-Willcox Co., Inc. Chapter 5 Power Supplies 33

6 Practice 5.5 Determine the condition of the following fuses. bad good Practice 5.6 Fill in the blanks for the statements about taking voltage measurements. Not all of the terms will be used high polarity 20 continuity low 1. When taking a voltage reading of an ac power source, need not be observed. 2. A good voltage reading of a power outlet will be plus or minus % of the 120-volt rating. 3. On extremely hot or cold days when the air conditioning or heating systems are controlling building temperature, the voltage reading of a power outlet may be Practice 5.7 Match the item to be measured to the appropriate switch setting. The same switch setting can be used more than once. Vac Vac 34 Computer Service and Repair Study Guide Copyright by Goodheart-Willcox Co., Inc.

7 Name volt wall outlet volt power connection from a molex connector Fuse from a power supply Reset switch on the front panel of a PC On/off switch on the front panel of a PC A wire from a connector to the power supply 6. Practice 5.8 Determine the power consumed by the following scenarios. 1. A PC drawing 10 A connected to a 120-volt power source. 2. A CD-ROM drive drawing 2 A from a 12-volt power source. 3. A printer drawing 3 A from a 120-volt power source. 4. A scanner drawing 5 A from a 120-volt power source. Practice 5.9 Label the power connectors. two by six 12-volt ATX12V main power mini connector SATApower power connector connector Molex connector ATX main power auxiliary power connector A. B. c. D. E. F. G. Copyright by Goodheart-Willcox Co., Inc. Chapter 5 Power Supplies 35

8 Practice 5.10 Fill in the blanks for the statements about power protection devices. The following terms may be used more than once. blackout power strip uninterruptible (UPS) brownout surge power supply 1. A(n) ensures a constant supply of quality electrical 1. power to the computer. 2. A(n) maintains power during blackouts, brownouts, 2. and surges. 3. A(n) is a low-power condition outage A momentary increase in voltage above normal voltage is 4. called a(n). 5. To protect a system against surges, you could use a(n) 5. with a metal oxide varistor. 6. To protect a computer system against brownouts, surges, 6. and blackouts, a(n) should be used. Practice 5.11 Name six signs that indicate a power supply may be defective. 36 Computer Service and Repair Study Guide Copyright by Goodheart-Willcox Co., Inc.