Power Supplies

Takes electricity from the wall socket and transforms it into electricity to run the motherboard and other internal components EXAM TIP Some questions on the CompTIA A+ certification exams could refer to a power supply as a PSU, for power supply unit. A power supply also falls into the category of field replaceable unit (FRU), which refers to the typical parts a tech should carry, such as RAM and a floppy disk drive.

Understanding Electricity The pressure of the electrons in the wire is called voltage and is measured in units called volts (V) The amount of electrons moving past a certain point on a wire is called the current or amperage, which is measured in units called amperes (amps or A) The amount of amps and volts needed by a particular device to function is expressed as how much wattage (watts or W) that device needs The correlation between the three is : V × A = W

Common Electrical Components

Circuit Breaker Circuit breakers and ground wires provide the basic protection from accidental overflow A circuit breaker is a heat-sensitive electrical switch rated at a certain amperage If you push too much amperage through the circuit breaker, the wiring inside will detect the increase in heat and automatically open, stopping the flow of electricity before the wiring overheats and breaks You reset the circuit breaker to reestablish the circuit and electricity will flow once more through the wires A ground wire provides a path of least resistance for electrons to flow back to ground in case of an accidental overflow EXAM TIP An electrical outlet must have a ground wire to be suitable for PC use!

Hot, Neutral, and Ground ( continued )

Multimeter A multimeter—often also referred to as a volt-ohm meter (VOM) or digital multimeter (DMM)— – –Enables you to measure a number of different aspects of electrical current – –Provides at least four major measurements: AC voltage, DC voltage, continuity, and resistance A multimeter consists of two probes: – –An analog or digital meter, and a dial to set the type of test you want to perform

UPS UPS - uninterruptible power supply (UPS) – –Protects your computer (and, more importantly, your data) in the event of a power sag or power outage – –A UPS essentially contains a big battery that will provide AC power to your computer, regardless of the power coming from the AC outlet

Uninterruptible Power Supplies Benefits Benefits –Condition line for brownouts and spikes –Provide backup power during a blackout –Protect against very high potentially damaging spikes Considerations Considerations –Cost –UPS rating –Degree of line conditioning –Warranty and service policies

Power Supplies The power supply unit (PSU) takes over, converting high-voltage AC into several DC voltages (notably, 5.0, 12.0, and 3.3 volts) usable by the delicate interior components PC uses the 12.0-volt current to power motors on devices such as hard drives and CD-ROM drives, and it uses the 5.0-volt and 3.3-volt current for support of onboard electronics

Power Supplies

Power to the Motherboard Use a 20- or 24-pin P1 power connector. Some motherboards may require special 4-, 6-, or 8-pin connectors to supply extra power

Power to Peripherals: Molex Molex Connectors – –The most common type of power connection for devices – –Need 5-volts or 12-volts of power is the Molex connector – –The Molex connector has notches, called chamfers, that guide its installation

Power to Peripherals: Mini Connectors Mini Connectors – –A second type of connector, called a mini connector – –Supplies 5 and 12 volts to peripherals, although only floppy disk drives in modern systems use this connector

Power to Peripherals: SATA Power Connectors SATA Power Connectors – –Serial ATA (SATA) hard drives need a special 15- pin SATA power connector – –The larger pin count supports the SATA hot- swappable feature, and 3.3 V, 5.0 V, and 12.0 V devices. SATA power connectors are L shaped, making it almost impossible to insert one incorrectly into a SATA drive – –No other device on your computer uses the SATA power connector

Power to Peripherals: Splitter & Adapters Not enough connectors to power all of the devices inside your PC – –Purchase splitters to create more connections

Power to Peripherals: Auxiliary Connector Motherboard power connector – –Commonly called an AUX connector – –To supply increased 3.3- and 5.0-volt current to the motherboard

Power Supply Form Factors All use standard ATX connectors, but differ in size and shape from standard ATX power supplies – –TFX12V A small power form factor optimized for low-profile ATX systems – –SFX12V A small power form factor optimized for systems using FlexATX motherboards – –CFX12V An L-shaped power supply optimized for Micro BTX systems – –LFX12V A small power form factor optimized for low-profile BTX systems

Protecting Your Computer System: General Precautions Make notes so you can backtrack Make notes so you can backtrack Remove packing materials from work area Remove packing materials from work area Keep components away from hair and clothing Keep components away from hair and clothing Keep screws and spacers in an orderly place Keep screws and spacers in an orderly place Don’t stack boards on top of each other Don’t stack boards on top of each other

Protecting Your Computer System: General Precautions Don’t touch chips on motherboard or expansion cards Don’t touch chips on motherboard or expansion cards Don’t touch chip with magnetized screwdriver Don’t touch chip with magnetized screwdriver Don’t change DIP switch settings with a graphite pencil Don’t change DIP switch settings with a graphite pencil

Protecting Your Computer System: General Precautions Have classroom instructor check your work before putting cover on and powering up Have classroom instructor check your work before putting cover on and powering up Turn off a computer before moving it Turn off a computer before moving it Keep disks away from magnetic fields, heat, and extreme cold Keep disks away from magnetic fields, heat, and extreme cold

Protecting Yourself Against Electricity Turn off power and unplug computer Turn off power and unplug computer Always use a ground bracelet Always use a ground bracelet Never touch inside of a computer while it is turned on Never touch inside of a computer while it is turned on Never remove cover or put your hands inside monitor or power supply Never remove cover or put your hands inside monitor or power supply

Static Electricity (or ESD) Can cause catastrophic failure or upset failure Can cause catastrophic failure or upset failure Protection against ESD Protection against ESD –Ground bracelet or static strap –Ground mats –Static shielding bags

Ground Bracelet

EMI (Electromagnetic Interference) Caused by magnetic field produced as side effect when electricity flows Caused by magnetic field produced as side effect when electricity flows Protection against EMI Protection against EMI –Cover expansion slots –Do not place system close to or on same circuit as high-powered electrical equipment –Use line conditioners

Upgrading Your Power Supply Sometimes necessary when you add new devices Sometimes necessary when you add new devices Easiest way to fix a power supply you suspect is faulty is to replace it Easiest way to fix a power supply you suspect is faulty is to replace it

Introduction to Troubleshooting Isolate the problem Isolate the problem –Problems that prevent PC from booting –Problems that occur after a successful boot Learn as much as you can by asking questions of user(s) Learn as much as you can by asking questions of user(s)

PC Problem Solving

Troubleshooting the Power System: General Guidelines Any burnt parts or odors? Any burnt parts or odors? Everything connected and turned on? Loose cable connections? Computer plugged in? Everything connected and turned on? Loose cable connections? Computer plugged in? All switches turned on? Wall outlet good? All switches turned on? Wall outlet good? If fan is not running, turn off computer: Connections to power supply secure? Cards securely seated? If fan is not running, turn off computer: Connections to power supply secure? Cards securely seated?

Troubleshooting the Power System: General Guidelines Check for correct wire connections to motherboard Check for correct wire connections to motherboard Remove nonessential expansion cards one at a time Remove nonessential expansion cards one at a time Vacuum entire unit Vacuum entire unit

Troubleshooting an ATX Power Supply

Troubleshooting the Power System Power supply itself Power supply itself Power supply fan Power supply fan Power problems with the motherboard Power problems with the motherboard Overheating Overheating

Preventing Overheating

Preventing Overheating ( continued )

Energy Star Systems (The Green Star) Satisfy energy-conserving standards of the US EPA Satisfy energy-conserving standards of the US EPA Generally have a standby program that switches device to sleep mode when not in use Generally have a standby program that switches device to sleep mode when not in use Apply to computers, monitors, printers, copiers, and fax machines Apply to computers, monitors, printers, copiers, and fax machines

Power Management Methods Advanced Power Management (APM) Advanced Power Management (APM) AT Attachment (ATA) for IDE drives AT Attachment (ATA) for IDE drives Display Power Management Signaling (DPMS) standards for monitors and video cards Display Power Management Signaling (DPMS) standards for monitors and video cards Advanced Configuration and Power Interface (ACPI) Advanced Configuration and Power Interface (ACPI)

Power Management Features Green timer on the motherboard Green timer on the motherboard Doze time Doze time Standby time Standby time Suspend time Suspend time Hard drive standby time Hard drive standby time

Power Management Setup Screen

Energy Star Monitors Most adhere to DPMS specifications Most adhere to DPMS specifications –Allow video card and monitor to go into sleep mode simultaneously

Changing Power Options