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Chapter 4 Form Factors Power Supplies


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Chapter 4 Form Factors Power Supplies

  1. 1. A+ Guide to Managing and Maintaining your PC, 6e Chapter 4 Form Factors and Power Supplies
  2. 2. Objectives <ul><li>Learn about different form factors and computer cases </li></ul><ul><li>Learn how electricity is measured </li></ul><ul><li>Learn how to protect your computer system against damaging changes in electrical power </li></ul><ul><li>Learn about Energy Star specifications </li></ul><ul><li>Learn how to troubleshoot electrical problems </li></ul>
  3. 3. Introduction <ul><li>Power supply: passes power to PC components </li></ul><ul><li>Elements driving type of power supply used in a PC: </li></ul><ul><ul><li>The motherboard </li></ul></ul><ul><ul><li>The form factor of the computer case </li></ul></ul><ul><li>Energy Star devices: designed to save energy </li></ul><ul><li>Electricity topics covered: </li></ul><ul><ul><li>Measurements of electricity </li></ul></ul><ul><ul><li>How electricity is delivered </li></ul></ul><ul><ul><li>Protecting a PC from electrical damage </li></ul></ul><ul><ul><li>Changing a defective power supply </li></ul></ul>
  4. 4. Computer Case, Motherboard, and Power Supply Form Factors <ul><li>Form factor </li></ul><ul><ul><li>Specifies size, shape, features of a hardware device </li></ul></ul><ul><li>Form factor for motherboard is chosen first </li></ul><ul><ul><li>Same form factor is used for case and power supply </li></ul></ul><ul><li>Using the same form factor assures you that: </li></ul><ul><ul><li>The motherboard fits the case </li></ul></ul><ul><ul><li>The powers supply cords provide proper voltage </li></ul></ul><ul><ul><li>Holes in the motherboard align with holes in the case </li></ul></ul><ul><ul><li>Holes in the case align with ports off the motherboard </li></ul></ul><ul><ul><li>Wires on the case match connections on motherboard </li></ul></ul>
  5. 5. Types of Form Factors <ul><li>AT (Advanced Technology) form factor </li></ul><ul><ul><li>Specified motherboard dimensions of 12” x 13.8” </li></ul></ul><ul><ul><li>Utilized by IBM AT PC in the 1980s </li></ul></ul><ul><li>Baby AT form factor </li></ul><ul><ul><li>Specified motherboard dimensions of 13” x 8.7” </li></ul></ul><ul><ul><li>Industry standard form factor from 1993 to 1997 </li></ul></ul><ul><li>ATX form factor </li></ul><ul><ul><li>Specified motherboard dimensions of 12” x 9.6” </li></ul></ul><ul><ul><li>Open specification that is most commonly used today </li></ul></ul><ul><ul><li>Includes all AT voltages plus a +3.3-volt circuit </li></ul></ul>
  6. 6. Figure 4-4 The CPU on an ATX motherboard sits opposite the expansion slots and does not block the room needed for long expansion cards
  7. 7. Types of Form Factors (continued) <ul><li>MicroATX form factor </li></ul><ul><ul><li>Reduces number of I/O slots on the motherboard </li></ul></ul><ul><li>BTX (Balanced Technology Extended) form factor </li></ul><ul><ul><li>Focuses on reducing heat and supporting motherboard </li></ul></ul><ul><li>LPX and Mini-LPX form factors </li></ul><ul><ul><li>Designed for low-end PC motherboards </li></ul></ul><ul><li>NLX form factor </li></ul><ul><ul><li>Developed to improve the LPX form factor </li></ul></ul><ul><li>Backplane Systems (Active and Passive) </li></ul><ul><ul><li>Use boards with slots, but little or no circuitry </li></ul></ul>
  8. 8. Figure 4-8 Improved airflow in a BTX case and motherboard makes it unnecessary to have a fan on top of the processor
  9. 9. Types of Cases <ul><li>Computer case (chassis) </li></ul><ul><ul><li>Houses power supply, motherboard, cards, drives </li></ul></ul><ul><ul><li>Panel switches/lights are used to control/monitor PC </li></ul></ul><ul><li>Desktop cases </li></ul><ul><ul><li>Motherboard on the bottom, power supply to the rear </li></ul></ul><ul><li>Tower cases </li></ul><ul><ul><li>Are up to 2 feet high and can contain several drives </li></ul></ul><ul><li>Notebook cases </li></ul><ul><ul><li>Used for all portables and have desktop components </li></ul></ul>
  10. 10. Figure 4-13 Tower and desktop cases
  11. 11. Measures and Properties of Electricity <ul><li>Successful PC technicians: </li></ul><ul><ul><li>Understand electricity </li></ul></ul><ul><ul><li>Know how to use electricity </li></ul></ul><ul><ul><li>Know how to measure electricity </li></ul></ul><ul><ul><li>Can protect computer equipment from electricity </li></ul></ul><ul><li>Units used to measure characteristics of electricity </li></ul><ul><ul><li>Volt, amp, ohm, and watt </li></ul></ul>
  12. 12. Table 4-2 Measures of electricity
  13. 13. AC and DC <ul><li>Alternating current (AC) </li></ul><ul><ul><li>Oscillatory current driven by an alternating voltage </li></ul></ul><ul><ul><li>Example: house current oscillates at 60 Hz </li></ul></ul><ul><li>Direct current (DC) </li></ul><ul><ul><li>Single direction current driven by constant voltage </li></ul></ul><ul><ul><li>Required by computer in small amounts, such as 5 V </li></ul></ul><ul><li>Rectifier: converts AC to DC </li></ul><ul><li>Transformer: changes ratio of current to voltage </li></ul><ul><li>Power supply acts as a transformer and rectifier </li></ul>
  14. 14. Figure 4-15 A transformer keeps power constant but changes the ratio of current to voltage
  15. 15. Hot, Neutral, and Ground <ul><li>Completing a circuit: </li></ul><ul><ul><li>AC travels from power station to house on a hot line </li></ul></ul><ul><ul><li>AC travels from panel to device using black (hot) wire </li></ul></ul><ul><ul><li>AC flows out of device circuit in a white (neutral) wire </li></ul></ul><ul><ul><li>AC returns to power station on a neutral line </li></ul></ul><ul><li>Short circuit: failure due to excess flow of electricity </li></ul><ul><ul><li>Fuses protect circuits by melting wire (breaking circuit) </li></ul></ul><ul><ul><li>Grounded neutral lines pass detoured AC to earth </li></ul></ul><ul><li>Lines in three-prong plugs: hot, neutral, and ground </li></ul><ul><ul><li>Verify wiring of outlet for plug using a receptacle tester </li></ul></ul>
  16. 16. Figure 4-16 Normally, electricity flows from hot to neutral to make a closed circuit in the controlled environment of an electrical device such as a lamp
  17. 17. Figure 4-18 Use a receptacle tester to verify that hot, neutral, and ground are wired correctly
  18. 18. Some Common Electric Components <ul><li>Materials used to make components: </li></ul><ul><ul><li>Conductors: weakly resist flow of current; e.g., copper </li></ul></ul><ul><ul><li>Insulators: highly resist flow of current; e.g., ceramics </li></ul></ul><ul><ul><li>Semiconductors: allow flow if charged; e.g., silicon </li></ul></ul><ul><li>Transistor </li></ul><ul><ul><li>Used to switch current on (1) and off (0) </li></ul></ul><ul><ul><li>Also used to amplify current </li></ul></ul><ul><ul><li>Made of three layers of semiconductor material </li></ul></ul><ul><ul><li>Charge applied to center layer controls switching </li></ul></ul>
  19. 19. Figure 4-19 Symbols for some electronic components and for ground
  20. 20. Some Common Electric Components (continued) <ul><li>Capacitor </li></ul><ul><ul><li>Holds electrical charge for a period of time </li></ul></ul><ul><ul><li>Used to create even flow of current in a PC </li></ul></ul><ul><li>Diode </li></ul><ul><ul><li>Allows electricity to flow in one direction only </li></ul></ul><ul><ul><li>Used to rectify current (convert AC to DC) </li></ul></ul><ul><li>Resistor </li></ul><ul><ul><li>Controls the amount of current flowing through device </li></ul></ul><ul><ul><li>Degree of resistance is measured in ohms </li></ul></ul>
  21. 21. Figure 4-20 Capacitors on a motherboard or other circuit board often have embedded crossed lines on top
  22. 22. Protecting Your Computer System <ul><li>Electrical threats to a computer system: </li></ul><ul><ul><li>Static electricity </li></ul></ul><ul><ul><li>Electromagnetic interference </li></ul></ul><ul><ul><li>Power surges </li></ul></ul><ul><li>Objectives in this section: </li></ul><ul><ul><li>Understand nature of each threat </li></ul></ul><ul><ul><li>Learn how to protect your system from these threats </li></ul></ul>
  23. 23. Static Electricity <ul><li>Static electricity (electrostatic discharge or ESD) </li></ul><ul><ul><li>Due to charge difference between user and device </li></ul></ul><ul><ul><li>Touching device causes discharge, damaging device </li></ul></ul><ul><li>ESD is particularly severe in dry and cold climates </li></ul><ul><li>How to protect system from ESD: </li></ul><ul><ul><li>Use ground bracelet or ESD gloves </li></ul></ul><ul><ul><li>Touch computer case before touching components </li></ul></ul><ul><li>Safety rule: unplug power cord before working in case </li></ul><ul><ul><li>Residual power in plugged device can cause damage </li></ul></ul>
  24. 24. EMI (Electromagnetic Interference) <ul><li>Caused by magnetic fields generated by current flow </li></ul><ul><li>RFI (radio frequency interference): </li></ul><ul><ul><li>EMI in radio frequency range affecting reception </li></ul></ul><ul><li>The crosstalk problem </li></ul><ul><ul><li>Data in cables crossing EM fields gets corrupted </li></ul></ul><ul><ul><li>Control crosstalk by shielding cables and power supply </li></ul></ul><ul><li>Use a tuned-down AM radio to detect EMI </li></ul><ul><li>Other ways to protect a device from EMI: </li></ul><ul><ul><li>Use line conditioners to filter out electrical noise </li></ul></ul><ul><ul><li>Move the PC to a new location </li></ul></ul>
  25. 25. Surge Protection and Battery Backup <ul><li>Storms and uneven AC flow cause power surges </li></ul><ul><li>Prevent power surges by installing an AC filter </li></ul><ul><li>Types of devices used to manage power surges: </li></ul><ul><ul><li>Surge suppressors </li></ul></ul><ul><ul><li>Power conditioners </li></ul></ul><ul><ul><li>Uninterruptible power supplies (UPSs) </li></ul></ul><ul><li>Use devices with UL (Underwriters Laboratory) logo </li></ul>
  26. 26. Surge Suppressors <ul><li>Also called a surge protector </li></ul><ul><li>Protects equipment from sudden changes in power </li></ul><ul><ul><li>Works by absorbing and/or blocking the surge </li></ul></ul><ul><li>Recommended features: </li></ul><ul><ul><li>Joules rating that is greater than 600 joules </li></ul></ul><ul><ul><li>Protection activated in less than 2 nanoseconds </li></ul></ul><ul><ul><li>Warranty for connected equipment and UL seal </li></ul></ul><ul><ul><li>Light indicating that surge protection is working </li></ul></ul><ul><ul><li>Data line protector for telephone line to modem </li></ul></ul><ul><ul><li>Let-through voltage rating and line noise filtering </li></ul></ul>
  27. 27. Figure 4-21 This surge suppressor has six electrical outlets, two phone jacks, and a power protection light
  28. 28. Power Conditioners <ul><li>Sometimes called line conditioners </li></ul><ul><li>Functions: </li></ul><ul><ul><li>Protect against spikes or swells (voltage surges) </li></ul></ul><ul><ul><li>Raise voltage during brownouts (voltage sags) </li></ul></ul><ul><li>Load supported measured in watts or volt-amps (VA) </li></ul><ul><li>Determining the VA needed to support your system: </li></ul><ul><ul><li>Multiply the amperage of each component by 120 V </li></ul></ul><ul><ul><li>Add up the VA for each component </li></ul></ul>
  29. 29. Uninterruptible Power Supply <ul><li>UPS offers three benefits: </li></ul><ul><ul><li>Conditions line to account for brownouts and spikes </li></ul></ul><ul><ul><li>Provides power backup when AC fails (blackout) </li></ul></ul><ul><ul><li>Provides protection against very high spikes </li></ul></ul><ul><li>Designs: standby, inline, and line-interactive </li></ul><ul><li>Smart (intelligent) UPS: controlled with software </li></ul><ul><li>What to consider when buying a UPS: </li></ul><ul><ul><li>UPS rating should exceed VA load by at least 25 % </li></ul></ul><ul><ul><li>Degree of line conditioning </li></ul></ul><ul><ul><li>Warranties, guarantees, and service policies </li></ul></ul>
  30. 30. Energy Star Systems (The Green Star) <ul><li>Energy Star systems have the U.S. Green Star </li></ul><ul><ul><li>Indicates device meets energy conserving standards </li></ul></ul><ul><ul><li>Devices: computers, monitors, printers, copiers, faxes </li></ul></ul><ul><li>Goals of Energy Star (a.k.a. Green) standards: </li></ul><ul><ul><li>Reduce overall electricity consumption </li></ul></ul><ul><ul><li>Protect and preserve natural resources </li></ul></ul><ul><li>How computer components meet standards </li></ul><ul><ul><li>Uses standby program for switching to sleep mode </li></ul></ul><ul><ul><li>No more than 30 watts used during sleep mode </li></ul></ul>
  31. 31. Power-Management Methods and Features <ul><li>Methods used to meet Energy Star standards: </li></ul><ul><ul><li>Advanced Configuration and Power Interface (ACPI) </li></ul></ul><ul><ul><ul><li>Standard used by most desktops and notebooks </li></ul></ul></ul><ul><ul><ul><li>Comprises four power-saving modes: S1 - S4 </li></ul></ul></ul><ul><ul><ul><li>Some features controlled by BIOS, others by Windows </li></ul></ul></ul><ul><ul><li>Advanced Power Management (APM) specification </li></ul></ul><ul><ul><li>AT Attachment (ATA) for various drives </li></ul></ul><ul><ul><li>Display Power Management Signaling (DPMS) </li></ul></ul>
  32. 32. Figure 4-24 A power management BIOS setup screen showing power-management features
  33. 33. Energy Star Monitors <ul><li>Display Power Management Signaling (DPMS) </li></ul><ul><ul><li>Specifications applying to video card and monitor </li></ul></ul><ul><ul><li>Allow both devices to simultaneously enter sleep mode </li></ul></ul><ul><li>Accessing energy settings in Windows 2000/XP </li></ul><ul><ul><li>Right-click the desktop and select Properties </li></ul></ul><ul><ul><ul><li>The Display Properties dialog box opens </li></ul></ul></ul><ul><ul><li>Click the Screen Saver tab </li></ul></ul><ul><ul><ul><li>If monitor is Energy Star–compliant, logo is at bottom </li></ul></ul></ul><ul><ul><li>Click Power button to open Power Options Properties </li></ul></ul>
  34. 34. Figure 4-25 Changing power options in Windows XP
  35. 35. Troubleshooting the Electrical System <ul><li>Problems can occur before or after boot </li></ul><ul><li>Problems can be consistent or inconsistent </li></ul><ul><li>Possible symptoms of an electrical problem: </li></ul><ul><ul><li>The PC appears “dead” </li></ul></ul><ul><ul><li>The PC sometimes halts during booting </li></ul></ul><ul><ul><li>Error codes or beeps occur during booting </li></ul></ul><ul><ul><li>You smell burnt parts or odors </li></ul></ul><ul><li>Check the simple things first </li></ul><ul><ul><li>Example: determine whether all switches are on </li></ul></ul>
  36. 36. Problems with External Power <ul><li>Brownout (reduced current) may create issues </li></ul><ul><ul><li>Check out other devices using the same circuit </li></ul></ul><ul><ul><li>Remove other devices to see if voltage increases </li></ul></ul><ul><li>Dealing with intermittent errors caused by noise: </li></ul><ul><ul><li>Use a line monitor to monitor and condition voltage </li></ul></ul>
  37. 37. Problems with Loose Internal Connections <ul><li>Can cause a system to appear dead or reboot itself </li></ul><ul><li>Troubleshooting tasks: </li></ul><ul><ul><li>Remove the cover of the case </li></ul></ul><ul><ul><li>Check all power connections </li></ul></ul><ul><ul><ul><li>Check cables linking power supply to motherboard </li></ul></ul></ul><ul><ul><ul><li>Check cables linking power supply to drives </li></ul></ul></ul>
  38. 38. Figure 4-26 For an ATX or BTX power supply, the remote switch wire must be connected to the motherboard before power will come on
  39. 39. Problems that Come and Go <ul><li>Intermittent symptoms indicating a post-boot problem </li></ul><ul><ul><li>The computer stops or hangs or reboots for no reason </li></ul></ul><ul><ul><li>Memory errors appear intermittently </li></ul></ul><ul><ul><li>Data is written incorrectly to the hard drive </li></ul></ul><ul><ul><li>The keyboard stops working at odd times </li></ul></ul><ul><ul><li>The motherboard fails or is damaged </li></ul></ul><ul><ul><li>Power supply overheats and becomes hot to the touch </li></ul></ul><ul><ul><li>The power supply fan becomes very noisy or stops </li></ul></ul><ul><li>Intermittent problems are often difficult to solve </li></ul>
  40. 40. Problems with an Inadequate Power Supply <ul><li>Power supply may not meet needs of new devices </li></ul><ul><li>Testing for an adequate power supply </li></ul><ul><ul><li>Make all devices in the system work at the same time </li></ul></ul><ul><ul><li>Example: copy files from new drive to old drive </li></ul></ul><ul><li>Simple solution: upgrade to a higher power supply </li></ul><ul><li>Calculating total wattage needed by system </li></ul><ul><ul><li>Multiply volts in circuit by amps required for device </li></ul></ul><ul><ul><li>Add all products to determine total wattage </li></ul></ul><ul><li>Power supply range: 200 watts to 600 watts </li></ul>
  41. 41. Problems with the Power Supply, Boards, or Drives <ul><li>Issues: </li></ul><ul><ul><li>Inadequate or faulty power supply </li></ul></ul><ul><ul><li>Components drawing power might be bad </li></ul></ul><ul><li>Problems caused: </li></ul><ul><ul><li>System hangs or gives intermittent errors </li></ul></ul><ul><ul><li>System reboots or does not boot at all </li></ul></ul><ul><li>Actions to take: </li></ul><ul><ul><li>Isolate and remove any faulty expansion cards </li></ul></ul><ul><ul><li>Upgrade or switch the power supply </li></ul></ul><ul><ul><li>Test voltage output of power supply with a multimeter </li></ul></ul>
  42. 42. Problems with the Power Supply Fan <ul><li>Defective fans usually hum before they stop working </li></ul><ul><li>Response to diagnosis of defective fan </li></ul><ul><ul><li>Replace fan or the entire power supply </li></ul></ul><ul><li>If replacement does not work, suspect another short </li></ul><ul><li>Do not operate a PC if the fan does not work </li></ul><ul><ul><li>Computers will overheat, damaging circuit boards </li></ul></ul><ul><li>Indirect sources of fan problems: </li></ul><ul><ul><li>Shorts in drives, motherboard, or expansion cards </li></ul></ul>
  43. 43. Power Problems with the Motherboard <ul><li>Bad contact between board component and chassis </li></ul><ul><ul><li>Short can seriously damage the motherboard </li></ul></ul><ul><ul><li>Check for missing or extra standoffs (spacers) </li></ul></ul><ul><li>Shorts in the circuit on the motherboard </li></ul><ul><ul><li>Look for damage to the bottom of the motherboard </li></ul></ul><ul><ul><li>Look for burned-out capacitors </li></ul></ul><ul><li>Frayed wires on connections can also cause shorts </li></ul><ul><ul><li>Test hard drive cables connected to motherboard </li></ul></ul>
  44. 44. Problems with Overheating <ul><li>Causes intermittent problems </li></ul><ul><li>May also cause the system to reboot or not boot </li></ul><ul><li>Temperature in a case should not exceed 100 ° F </li></ul><ul><li>Some possible solutions: </li></ul><ul><ul><li>Remove dust from power supply, vents, heat sink </li></ul></ul><ul><ul><li>Secure cables and cords with tie wraps </li></ul></ul><ul><ul><li>Install another exhaust fan on the rear of the case </li></ul></ul><ul><ul><li>Install a fan in expansion slot next to video card </li></ul></ul><ul><ul><li>Replace component that is damaged </li></ul></ul>
  45. 45. Figure 4-27 Install one exhaust fan on the rear of the case to help pull air through the case
  46. 46. Replacing the Power Supply <ul><li>The power supply is a field replaceable unit (FRU) </li></ul><ul><li>Criteria for replacement power supply to meet: </li></ul><ul><ul><li>Uses the correct form factor </li></ul></ul><ul><ul><li>Adequately rated for power in watts </li></ul></ul><ul><ul><li>Has all power connectors needed by your system </li></ul></ul><ul><li>Before replacing power supply, test new device </li></ul><ul><ul><li>Connect components to new power supply </li></ul></ul><ul><ul><li>Turn on PC and observe whether problem is solved </li></ul></ul><ul><ul><li>If problem is solved, perform replacement procedure </li></ul></ul>
  47. 47. Summary <ul><li>Form factor: specifies size, shape, features of device </li></ul><ul><li>Motherboard, power supply, and case share the same form factor, such as ATX </li></ul><ul><li>Three types of cases: desktop, tower, and notebook </li></ul><ul><li>Quantities that characterize electricity: voltage, current, resistance, and power </li></ul><ul><li>Current flows from hot wires to neutral wires; excess current escapes through grounds </li></ul>
  48. 48. Summary (continued) <ul><li>AC supplied by power station is transformed and rectified before flowing into the PC </li></ul><ul><li>Major components in a circuit board: transistor, capacitor, diode, resistor </li></ul><ul><li>Electrical threats: ESD, EMI, uneven current flow, sudden power surges (or spikes) </li></ul><ul><li>Energy Star standards promote energy conservation </li></ul><ul><li>PCs comply with Energy Star standards by enabling devices to enter into a low power sleep mode </li></ul>