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Edit Comment Close Premium member Presentation Transcript Slide 1: PowerPoint for Computer Service and Repair by JoAnne Keltner Goodheart-Willcox Publisher 18604 West Creek Drive Tinley Park, IL 60477 www.g-w.com Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational purposes only. Chapter 5Power Supplies : Chapter 5Power Supplies Power Supply : Power Supply The power supply converts standard 120-volt power from the wall outlet to dc voltage levels appropriate to the electronic systems of the computer. Importance to the PC Technician : Importance to the PC Technician Troubleshoot a faulty power supply. Properly perform a computer upgrade. Objectives : Objectives Define electrical energy. Describe the terms ampere, volt, and ohm in relation to electrical energy. Explain the wattage rating of a power supply unit. Determine power supply requirements for a PC. Identify possible commercial power problems. Objectives : Objectives Use a digital multimeter to troubleshoot a power supply. Apply wattage values when selecting the proper power supply and computer devices. Identify various power supply form factors. Explain the use of UPS and power protection devices. Presentation Outline : Presentation Outline Electrical Energy and Power Electrical Measurements Clean Electrical Power The PC Power Supply 1 2 3 4 5 Troubleshooting the Power Supply Electrical Energy and Power : Electrical Energy and Power 1 What Is Electrical Energy? : What Is Electrical Energy? Electrical energy is the flow of electrons. Electrical pressure Electrons Conductor Direct Current (DC) : Direct Current (DC) Direct current (dc) flows in one direction. An example of a dc power source is a battery. Alternating Current (AC) : Alternating Current (AC) Alternating current (ac) is in a state of constant change or alternating polarities. Complete Cycle Alternating Current Cycle : Alternating Current Cycle Voltage : Voltage Voltage is the amount of electrical pressure present in a power source. Measured in volts (V). 6 V Electrical pressure Current : Current Current is the amount of electron flow. Measured in amperes (A). Electron flow Resistance : Resistance Resistance is the opposition to current flow. Measured in ohms and represented with the omega symbol (Ω) Resistance Power : Power Power is the amount of electrical energy provided or used by equipment. Measured in watts (W). Determined with the following formula: Watts = Volts Amps Electrical Relationships : Electrical Relationships E I I2 R E2 R P I R E E R P E P R I R PR P I P I2 E2 P E I Volt-Amperes (VA) : Volt-Amperes (VA) A PC power supply is rated in volt-amperes (VA) and in watts. Watts and VA Comparisons : Watts and VA Comparisons Total wattage rating can be quite different from the calculated wattage rating (VA). Review : Review What is electrical energy? Electrical energy is the flow of electrons. Review : Review The amount of electrical pressure present in a circuit or power source is called _____. voltage Review : Review Voltage is measured in _____. volts Review : Review The amount of electron flow through a conductor is called _____. current Review : Review Current is measured in _____. amperes Review : Review The opposition to current flow is called _____. resistance Review : Review The unit of resistance is the _____. ohm Review : Review The amount of electrical energy provided or used by equipment is called _____. power Review : Review What is the calculated wattage of a computer that draws 3 A of current? 3 A 120 V = 360 W Electrical Measurements : Electrical Measurements 2 Reading Voltage : Reading Voltage Insert meter leads into the appropriate jacks on the multimeter. If multimeter is not autorange, turn the voltage selector switch to the next highest voltage of what you intend to read. Touch the test location with probes. Reading Resistance : Reading Resistance Insert meter leads into the appropriate jacks on the multimeter. Be sure that the electrical power to the circuit or device you are about to measure is off. Set the selector switch to the highest value of resistance. Touch the test probes together to see if the meter is working properly. (Should read zero ohms.) Touch the probes to the circuit or device to be tested. Reading Resistance—Example 1 : Reading Resistance—Example 1 When reading the resistance value of a component, remove it from the circuit to prevent an inaccurate reading caused by backfeed. Backfeed Situation Reading Resistance—Example 2 : Reading Resistance—Example 2 Testing a Fuse Reading Resistance—Example 3 : Reading Resistance—Example 3 Testing for Continuity Reading Resistance—Example 4 : Reading Resistance—Example 4 Testing a Switch Review : Review When reading voltage with a multimeter, the _____ selector switch should be set to the next highest value of what you intend to read. voltage Review : Review When reading _____, you must make sure the electrical power to the circuit or device you are about to measure is off. resistance Review : Review When reading resistance, set the selector switch to the highest value of _____. resistance Review : Review The _____ function of a multimeter can be used to test a fuse, a switch, and for continuity. ohmmeter, or resistance Clean Electrical Power : Clean Electrical Power 3 Clean Power : Clean Power A commercial electric supply that has a steady voltage level. No voltage spikes. Other Electrical Energy Conditions : Other Electrical Energy Conditions Surge—A higher than desired voltage level is present. Brownout—A lower than desired voltage level is present. Blackout—No electrical voltage is present. Ways to Ensure Clean Power : Ways to Ensure Clean Power Power strip. Uninterruptible power supply (UPS). Dedicated circuit. Click each link for details. Power Strip : Power Strip Has a metal oxide varistor (MOV) to protect against surges. Should not connect to a total of over 1600 watts of equipment. Do not daisy chain power strips! Daisy chain Uninterruptible Power Supply (UPS) : Uninterruptible Power Supply (UPS) An uninterruptible power supply (UPS) ensures a constant supply of quality electrical power to the computer system. UPS (Courtesy of APC) UPS Components and Operation : UPS Components and Operation Dedicated Circuit : Dedicated Circuit Dedicated circuit Typical Home Distribution : Typical Home Distribution Review : Review Name four possible commercial power problems. Spike Surge Brownout Black out Review : Review Name three ways to ensure clean power is provided to a computer system. Power strip Uninterruptible power supply Dedicated circuit Review : Review Which of the following ensures a constant supply of quality electrical power to the computer system in the event of a power failure? Power strip Uninterruptible power supply Dedicated circuit The PC Power Supply : The PC Power Supply 4 The PC Power Supply : The PC Power Supply Converts 120 volts of ac power from the wall outlet to dc voltage levels appropriate for the electronic systems of the PC. Typical voltage levels provided are +12, +5, +3.3, –12, and –5. Inside the Power Supply : Inside the Power Supply Molex Connector : Molex Connector The Molex connector is a four-wire, D-shaped connector that delivers +5-volt and +12-volt signals from the power supply. Pin 1 +12 Vdc Common Common +5 Vdc Pin 4 Mini Connector : Mini Connector The mini connector is a two-pin connector that delivers a +5-volt signal from the power supply. A variation of this connector has four wires and delivers +12-volt and +5-volt signals. Pin 1 Pin 4 +5 Vdc Common Common +12 Vdc ATX and ATX12V Power MB Connectors : ATX and ATX12V Power MB Connectors ATX ATX12V ATX : ATX Pin 1 Pin 11 ATX12V : ATX12V Voltages are distributed by rails. Power Good Signal : Power Good Signal A power good signal is sent from the power supply to the motherboard to verify that it is functioning normally. Verified during the POST. PWR_OK connection. Standby Power Connection : Standby Power Connection Standby power connection is also called soft power. Provides power to the keyboard when the computer is in sleep mode. Can also provide power to a network card when “wakeup on LAN” is set in the BIOS. Two by Six 12-Volt Connector : Two by Six 12-Volt Connector Pin 1 Pin 3 Common Common +12 Vdc +12 Vdc Aux Power Connector : Aux Power Connector Common Common Common Pin 1 Pin 6 +3.3 Vdc +3.3 Vdc +5 Vdc SATA Power Connector : SATA Power Connector +3.3 Vdc +3.3 Vdc +3.3 Vdc +12 Vdc +12 Vdc +12 Vdc +5 Vdc +5 Vdc +5 Vdc Common Common Common Common Power Supply Form Factor : Power Supply Form Factor Shape of the power supply. Typically named after the motherboard form factors, such as AT, Baby AT, LPX, ATX, ATX12V, and NLX. Nonstandard and proprietary power supplies exist. Always check the manufacturer's specifications before replacing. Power Management Standards : Power Management Standards Advanced Configuration and Power Interface (ACPI). Allows the OS to control power management. Enabled by the BIOS, but not controlled by the BIOS. Advanced Power Management (APM). Allows the BIOS to control power management. Replaced by ACPI. APM Power Conditions : APM Power Conditions Windows XP Power Options : Windows XP Power Options Accessed through Control Panel | System and Maintenance. Or Control Panel | Power Options. Windows Vista Power Options : Windows Vista Power Options Accessed through Control Panel | Performance and Maintenance. Review : Review Which motherboard power connector is designed for the ATX form factor? Review : Review Which motherboard power connector is designed for the ATX12V form factor? Review : Review A power saving design that is managed by the operating system is _____. Advanced Configuration and Power Interface (ACPI) Review : Review A power saving design that is managed by the BIOS is _____. Advanced Power Management (APM) Troubleshooting the Power Supply : Troubleshooting the Power Supply 5 Indicators That Power Supply Is Bad : Indicators That Power Supply Is Bad Inoperable cooling fans. Smoke. Circuit breaker tripping. Automatic rebooting. Electric shock. Excessive heat. Replacing the Power Supply : Replacing the Power Supply Form factor must match original power supply. The wattage capacity of the power supply must match or exceed that of the original power supply. Installation Procedures : Installation Procedures Be absolutely sure the computer is disconnected from the power source. Sketch all the connections between the original PS and the computer components. Carefully remove all power connections. Remove retaining/mounting screws from the case that secure the power supply. Installation Procedures (Cont.) : Installation Procedures (Cont.) Place the new PS in the case and secure the retaining/mounting screw. Reconnect the PS connections to the motherboard and devices. Place extra power connections in a neat bundle. Verify all connections are secure. Replace the cover on the PC. Review : Review Name some indicators that the power supply may be bad. Inoperable cooling fans. Smoke. Circuit breaker tripping. Automatic rebooting. Electric shock. Excessive heat. Review : Review What should be considered when replacing a power supply? Form factor must match original power supply. The wattage capacity of the power supply must match or exceed that of the original power supply. Glossary : Glossary Advanced Configuration and Power Interface (ACPI) : Advanced Configuration and Power Interface (ACPI) An open industry power management standard for desktops, laptops, and servers. ACPI allows the operating system to control the power management features. Advanced Power Management (APM) : Advanced Power Management (APM) Power management standard that allows the BIOS to control power management features of the computer system. APM is configured in the BIOS Setup program and determines the amount of time before the display and hard disk drive are turned off. Alternating Current (AC) : Alternating Current (AC) Electrical current that reverses direction cyclically. Amperes (A) : Amperes (A) A scale used in measuring the volume of electron flow in a circuit. Backfeed : Backfeed A type of ohmmeter reading in which the resistance is measured through the circuit components even though the circuit is open. Continuity : Continuity A state of connectedness. In electronics, an unbroken circuit is said to have continuity. Current : Current The electron flow in a circuit. Cycle : Cycle The completed sequence of flow, first in one direction and then in the other. Dedicated Circuit : Dedicated Circuit A circuit installed in an electrical power distribution system that is designed to serve only computer equipment. Direct Current (DC) : Direct Current (DC) Electrical current that flows in one direction. Fuse : Fuse An inexpensive, passive component that is engineered to burn open at a predetermined amperage, protecting the rest of the circuit from overload. Metal Oxide Varistor (MOV) : Metal Oxide Varistor (MOV) A gate in a surge suppressor that becomes conductive at a given voltage, causing current to bypass the equipment plugged into the suppressor. Mini Connector : Mini Connector A two-pin connector that delivers a +5-volt signal from the power supply. A variation of this connector has four wires and delivers both +12-volt and +5-volt signals. Molex Connector : Molex Connector A four-wire, D-shaped connector that delivers +12-volt and +5-volt signals from the power supply. Power : Power The amount of electrical energy provided or used by equipment. Power Good Signal : Power Good Signal A signal sent from the power supply to the motherboard to verify that it is functioning normally. Rails : Rails The conductor paths inside the metal power supply case of an ATX12V power supply. There is one rail for each voltage level. Each rail then supplies the electrical voltage level to all connectors that require that specific voltage. Resistance : Resistance The opposition to the flow of electrical energy. Soft Power : Soft Power Another term for the features provided by a standby power connection. Standby Power Connection : Standby Power Connection Provides power to reactivate or wake up a system in standby mode. Uninterruptible Power Supply : Uninterruptible Power Supply A power supply that ensures a constant supply of quality electrical power to the computer system. Volt-Amperes (VA) : Volt-Amperes (VA) An alternative scale for measuring electrical power. Voltage : Voltage The amount of electrical pressure present in a circuit or power source. Volts (V) : Volts (V) A scale used in measuring electrical pressure (electromotive force). Watts (W) : Watts (W) A scale used in measuring electrical power. Discussion Question : Discussion Question You are troubleshooting a PC that appears to be dead. What are some possible causes of this condition? You do not have the permission to view this presentation. In order to view it, please contact the author of the presentation.
Power Supplies eduardoveliz Download Post to : URL : Related Presentations : Share Add to Flag Embed Email Send to Blogs and Networks Add to Channel Uploaded from authorPOINT lite Insert YouTube videos in PowerPont slides with aS Desktop Copy embed code: (To copy code, click on the text box) Embed: URL: Thumbnail: WordPress Embed Customize Embed The presentation is successfully added In Your Favorites. Views: 1300 Category: Science & Tech.. License: All Rights Reserved Like it (2) Dislike it (0) Added: April 24, 2010 This Presentation is Public Favorites: 0 Presentation Description No description available. Comments Posting comment... By: Okharry (14 month(s) ago) I would like to read this presentation at a later date, kindly allow me to download. Thanks in advance. Saving..... Post Reply Close Saving..... Edit Comment Close Premium member Presentation Transcript Slide 1: PowerPoint for Computer Service and Repair by JoAnne Keltner Goodheart-Willcox Publisher 18604 West Creek Drive Tinley Park, IL 60477 www.g-w.com Goodheart-Willcox Co., Inc. Permission granted to reproduce for educational purposes only. Chapter 5Power Supplies : Chapter 5Power Supplies Power Supply : Power Supply The power supply converts standard 120-volt power from the wall outlet to dc voltage levels appropriate to the electronic systems of the computer. Importance to the PC Technician : Importance to the PC Technician Troubleshoot a faulty power supply. Properly perform a computer upgrade. Objectives : Objectives Define electrical energy. Describe the terms ampere, volt, and ohm in relation to electrical energy. Explain the wattage rating of a power supply unit. Determine power supply requirements for a PC. Identify possible commercial power problems. Objectives : Objectives Use a digital multimeter to troubleshoot a power supply. Apply wattage values when selecting the proper power supply and computer devices. Identify various power supply form factors. Explain the use of UPS and power protection devices. Presentation Outline : Presentation Outline Electrical Energy and Power Electrical Measurements Clean Electrical Power The PC Power Supply 1 2 3 4 5 Troubleshooting the Power Supply Electrical Energy and Power : Electrical Energy and Power 1 What Is Electrical Energy? : What Is Electrical Energy? Electrical energy is the flow of electrons. Electrical pressure Electrons Conductor Direct Current (DC) : Direct Current (DC) Direct current (dc) flows in one direction. An example of a dc power source is a battery. Alternating Current (AC) : Alternating Current (AC) Alternating current (ac) is in a state of constant change or alternating polarities. Complete Cycle Alternating Current Cycle : Alternating Current Cycle Voltage : Voltage Voltage is the amount of electrical pressure present in a power source. Measured in volts (V). 6 V Electrical pressure Current : Current Current is the amount of electron flow. Measured in amperes (A). Electron flow Resistance : Resistance Resistance is the opposition to current flow. Measured in ohms and represented with the omega symbol (Ω) Resistance Power : Power Power is the amount of electrical energy provided or used by equipment. Measured in watts (W). Determined with the following formula: Watts = Volts Amps Electrical Relationships : Electrical Relationships E I I2 R E2 R P I R E E R P E P R I R PR P I P I2 E2 P E I Volt-Amperes (VA) : Volt-Amperes (VA) A PC power supply is rated in volt-amperes (VA) and in watts. Watts and VA Comparisons : Watts and VA Comparisons Total wattage rating can be quite different from the calculated wattage rating (VA). Review : Review What is electrical energy? Electrical energy is the flow of electrons. Review : Review The amount of electrical pressure present in a circuit or power source is called _____. voltage Review : Review Voltage is measured in _____. volts Review : Review The amount of electron flow through a conductor is called _____. current Review : Review Current is measured in _____. amperes Review : Review The opposition to current flow is called _____. resistance Review : Review The unit of resistance is the _____. ohm Review : Review The amount of electrical energy provided or used by equipment is called _____. power Review : Review What is the calculated wattage of a computer that draws 3 A of current? 3 A 120 V = 360 W Electrical Measurements : Electrical Measurements 2 Reading Voltage : Reading Voltage Insert meter leads into the appropriate jacks on the multimeter. If multimeter is not autorange, turn the voltage selector switch to the next highest voltage of what you intend to read. Touch the test location with probes. Reading Resistance : Reading Resistance Insert meter leads into the appropriate jacks on the multimeter. Be sure that the electrical power to the circuit or device you are about to measure is off. Set the selector switch to the highest value of resistance. Touch the test probes together to see if the meter is working properly. (Should read zero ohms.) Touch the probes to the circuit or device to be tested. Reading Resistance—Example 1 : Reading Resistance—Example 1 When reading the resistance value of a component, remove it from the circuit to prevent an inaccurate reading caused by backfeed. Backfeed Situation Reading Resistance—Example 2 : Reading Resistance—Example 2 Testing a Fuse Reading Resistance—Example 3 : Reading Resistance—Example 3 Testing for Continuity Reading Resistance—Example 4 : Reading Resistance—Example 4 Testing a Switch Review : Review When reading voltage with a multimeter, the _____ selector switch should be set to the next highest value of what you intend to read. voltage Review : Review When reading _____, you must make sure the electrical power to the circuit or device you are about to measure is off. resistance Review : Review When reading resistance, set the selector switch to the highest value of _____. resistance Review : Review The _____ function of a multimeter can be used to test a fuse, a switch, and for continuity. ohmmeter, or resistance Clean Electrical Power : Clean Electrical Power 3 Clean Power : Clean Power A commercial electric supply that has a steady voltage level. No voltage spikes. Other Electrical Energy Conditions : Other Electrical Energy Conditions Surge—A higher than desired voltage level is present. Brownout—A lower than desired voltage level is present. Blackout—No electrical voltage is present. Ways to Ensure Clean Power : Ways to Ensure Clean Power Power strip. Uninterruptible power supply (UPS). Dedicated circuit. Click each link for details. Power Strip : Power Strip Has a metal oxide varistor (MOV) to protect against surges. Should not connect to a total of over 1600 watts of equipment. Do not daisy chain power strips! Daisy chain Uninterruptible Power Supply (UPS) : Uninterruptible Power Supply (UPS) An uninterruptible power supply (UPS) ensures a constant supply of quality electrical power to the computer system. UPS (Courtesy of APC) UPS Components and Operation : UPS Components and Operation Dedicated Circuit : Dedicated Circuit Dedicated circuit Typical Home Distribution : Typical Home Distribution Review : Review Name four possible commercial power problems. Spike Surge Brownout Black out Review : Review Name three ways to ensure clean power is provided to a computer system. Power strip Uninterruptible power supply Dedicated circuit Review : Review Which of the following ensures a constant supply of quality electrical power to the computer system in the event of a power failure? Power strip Uninterruptible power supply Dedicated circuit The PC Power Supply : The PC Power Supply 4 The PC Power Supply : The PC Power Supply Converts 120 volts of ac power from the wall outlet to dc voltage levels appropriate for the electronic systems of the PC. Typical voltage levels provided are +12, +5, +3.3, –12, and –5. Inside the Power Supply : Inside the Power Supply Molex Connector : Molex Connector The Molex connector is a four-wire, D-shaped connector that delivers +5-volt and +12-volt signals from the power supply. Pin 1 +12 Vdc Common Common +5 Vdc Pin 4 Mini Connector : Mini Connector The mini connector is a two-pin connector that delivers a +5-volt signal from the power supply. A variation of this connector has four wires and delivers +12-volt and +5-volt signals. Pin 1 Pin 4 +5 Vdc Common Common +12 Vdc ATX and ATX12V Power MB Connectors : ATX and ATX12V Power MB Connectors ATX ATX12V ATX : ATX Pin 1 Pin 11 ATX12V : ATX12V Voltages are distributed by rails. Power Good Signal : Power Good Signal A power good signal is sent from the power supply to the motherboard to verify that it is functioning normally. Verified during the POST. PWR_OK connection. Standby Power Connection : Standby Power Connection Standby power connection is also called soft power. Provides power to the keyboard when the computer is in sleep mode. Can also provide power to a network card when “wakeup on LAN” is set in the BIOS. Two by Six 12-Volt Connector : Two by Six 12-Volt Connector Pin 1 Pin 3 Common Common +12 Vdc +12 Vdc Aux Power Connector : Aux Power Connector Common Common Common Pin 1 Pin 6 +3.3 Vdc +3.3 Vdc +5 Vdc SATA Power Connector : SATA Power Connector +3.3 Vdc +3.3 Vdc +3.3 Vdc +12 Vdc +12 Vdc +12 Vdc +5 Vdc +5 Vdc +5 Vdc Common Common Common Common Power Supply Form Factor : Power Supply Form Factor Shape of the power supply. Typically named after the motherboard form factors, such as AT, Baby AT, LPX, ATX, ATX12V, and NLX. Nonstandard and proprietary power supplies exist. Always check the manufacturer's specifications before replacing. Power Management Standards : Power Management Standards Advanced Configuration and Power Interface (ACPI). Allows the OS to control power management. Enabled by the BIOS, but not controlled by the BIOS. Advanced Power Management (APM). Allows the BIOS to control power management. Replaced by ACPI. APM Power Conditions : APM Power Conditions Windows XP Power Options : Windows XP Power Options Accessed through Control Panel | System and Maintenance. Or Control Panel | Power Options. Windows Vista Power Options : Windows Vista Power Options Accessed through Control Panel | Performance and Maintenance. Review : Review Which motherboard power connector is designed for the ATX form factor? Review : Review Which motherboard power connector is designed for the ATX12V form factor? Review : Review A power saving design that is managed by the operating system is _____. Advanced Configuration and Power Interface (ACPI) Review : Review A power saving design that is managed by the BIOS is _____. Advanced Power Management (APM) Troubleshooting the Power Supply : Troubleshooting the Power Supply 5 Indicators That Power Supply Is Bad : Indicators That Power Supply Is Bad Inoperable cooling fans. Smoke. Circuit breaker tripping. Automatic rebooting. Electric shock. Excessive heat. Replacing the Power Supply : Replacing the Power Supply Form factor must match original power supply. The wattage capacity of the power supply must match or exceed that of the original power supply. Installation Procedures : Installation Procedures Be absolutely sure the computer is disconnected from the power source. Sketch all the connections between the original PS and the computer components. Carefully remove all power connections. Remove retaining/mounting screws from the case that secure the power supply. Installation Procedures (Cont.) : Installation Procedures (Cont.) Place the new PS in the case and secure the retaining/mounting screw. Reconnect the PS connections to the motherboard and devices. Place extra power connections in a neat bundle. Verify all connections are secure. Replace the cover on the PC. Review : Review Name some indicators that the power supply may be bad. Inoperable cooling fans. Smoke. Circuit breaker tripping. Automatic rebooting. Electric shock. Excessive heat. Review : Review What should be considered when replacing a power supply? Form factor must match original power supply. The wattage capacity of the power supply must match or exceed that of the original power supply. Glossary : Glossary Advanced Configuration and Power Interface (ACPI) : Advanced Configuration and Power Interface (ACPI) An open industry power management standard for desktops, laptops, and servers. ACPI allows the operating system to control the power management features. Advanced Power Management (APM) : Advanced Power Management (APM) Power management standard that allows the BIOS to control power management features of the computer system. APM is configured in the BIOS Setup program and determines the amount of time before the display and hard disk drive are turned off. Alternating Current (AC) : Alternating Current (AC) Electrical current that reverses direction cyclically. Amperes (A) : Amperes (A) A scale used in measuring the volume of electron flow in a circuit. Backfeed : Backfeed A type of ohmmeter reading in which the resistance is measured through the circuit components even though the circuit is open. Continuity : Continuity A state of connectedness. In electronics, an unbroken circuit is said to have continuity. Current : Current The electron flow in a circuit. Cycle : Cycle The completed sequence of flow, first in one direction and then in the other. Dedicated Circuit : Dedicated Circuit A circuit installed in an electrical power distribution system that is designed to serve only computer equipment. Direct Current (DC) : Direct Current (DC) Electrical current that flows in one direction. Fuse : Fuse An inexpensive, passive component that is engineered to burn open at a predetermined amperage, protecting the rest of the circuit from overload. Metal Oxide Varistor (MOV) : Metal Oxide Varistor (MOV) A gate in a surge suppressor that becomes conductive at a given voltage, causing current to bypass the equipment plugged into the suppressor. Mini Connector : Mini Connector A two-pin connector that delivers a +5-volt signal from the power supply. A variation of this connector has four wires and delivers both +12-volt and +5-volt signals. Molex Connector : Molex Connector A four-wire, D-shaped connector that delivers +12-volt and +5-volt signals from the power supply. Power : Power The amount of electrical energy provided or used by equipment. Power Good Signal : Power Good Signal A signal sent from the power supply to the motherboard to verify that it is functioning normally. Rails : Rails The conductor paths inside the metal power supply case of an ATX12V power supply. There is one rail for each voltage level. Each rail then supplies the electrical voltage level to all connectors that require that specific voltage. Resistance : Resistance The opposition to the flow of electrical energy. Soft Power : Soft Power Another term for the features provided by a standby power connection. Standby Power Connection : Standby Power Connection Provides power to reactivate or wake up a system in standby mode. Uninterruptible Power Supply : Uninterruptible Power Supply A power supply that ensures a constant supply of quality electrical power to the computer system. Volt-Amperes (VA) : Volt-Amperes (VA) An alternative scale for measuring electrical power. Voltage : Voltage The amount of electrical pressure present in a circuit or power source. Volts (V) : Volts (V) A scale used in measuring electrical pressure (electromotive force). Watts (W) : Watts (W) A scale used in measuring electrical power. Discussion Question : Discussion Question You are troubleshooting a PC that appears to be dead. What are some possible causes of this condition?