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Electricity and power systems

Electricity and power systems

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Electricity and power systems

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  1. Electricity and power systems Unit objectives • Measure and describe the characteristics of electricity • Identify static electricity and follow ESD safe practices when working with computers • Describe the purpose and features of power supplies and install a new power supply into a PC • Troubleshoot faulty power supplies

  2. Topic A • Topic A: Electricity and electronics • Topic B: Static electricity • Topic C: Power supplies • Topic D: Power supply troubleshooting

  3. Electricity characteristics • Voltage • Current • Alternating or direct current • Resistance and impedance • Power and energy

  4. Activity A-1 Examining the characteristicsof electricity

  5. Electrical safety • Current can kill • The 1–10–100 rule • Calculating current V = i * r • Resistance of the human body

  6. Safety precautions • Don’t touch exposed contacts • Touch only insulated handles of tools • Leave covers on equipment • Work one-handed • Don’t stick things into electrical sockets • Remove jewelry, watches, etc. • Keep hands clean and dry • Don’t work in wet surroundings

  7. Activity A-2 Considering electrical safety

  8. Digital multimeter

  9. Analog multimeter

  10. Using a multimeter • Measuring resistance • Measuring voltage • Measuring current • Measuring continuity

  11. Activity A-3 Measuring electrical values

  12. Topic B • Topic A: Electricity and electronics • Topic B: Static electricity • Topic C: Power supplies • Topic D: Power supply troubleshooting

  13. Static electricity • Build up of charges • Static dangers • Discharge voltages • 3,000+ volts to feel • 8,000+ volts to see spark • 35,000 volts on a dry day on carpet • 1,000 volts can damage electronics

  14. Prevent static build-up • Don’t shuffle your feet • Increase the humidity • Keep yourself grounded • Wear cotton, not synthetics • Remove carpeting • Use air ionization system

  15. Prevent static discharge • Equalize charge differences safely • Unplug the equipment • Touch its metal chassis or power supply • Keep yourself and equipment connected • Wrist straps and anti-static mats • Static-safe bags

  16. Static wrist strap

  17. Typical internal components CD-ROM drive Power supply CPU / fan Adapter card Motherboard Hard drive

  18. Slide catches Slide catch, move to open side of case

  19. Determining which side to open Open this side to access components Ports and connectors attached to motherboard

  20. Removable front cover Alignment posts Alignment holes Spring catches

  21. Activity B-1 Opening the computer case while following proper ESD precautions

  22. Topic C • Topic A: Electricity and electronics • Topic B: Static electricity • Topic C: Power supplies • Topic D: Power supply troubleshooting

  23. A PC power supply

  24. Voltage selection switch

  25. Typical power requirements

  26. Standard outputs

  27. Power_Good signal • Signals CPU that power is stable and sufficient • +5 V over specific wire • Must arrive at correct time

  28. Peripheral power connector • “Molex” connector

  29. Floppy power connector • “Berg” connector

  30. SATA power connector • New, for Serial ATA drives

  31. Wire colors • Yellow = +12 V • Red = +5 V • Black = ground

  32. Motherboard power connectors

  33. Power supply form factors

  34. Activity C-1 Examining a power supply and connectors

  35. Topic D • Topic A: Electricity and electronics • Topic B: Static electricity • Topic C: Power supplies • Topic D: Power supply troubleshooting

  36. Troubleshooting symptoms • Computer fails to boot when powered on, but boots after pressing Ctrl + Alt + Delete • Computer intermittently stops working or reboots • You don’t have sufficient power connectors to connect all the devices you want to install • Computer fails to boot at all, with no lights or beeps; fans don’t start • Computer fails to boot, but fans start

  37. Activity D-1 Troubleshooting power supply problems

  38. Unit summary • Measured and described the characteristics of electricity • Identified static electricity and followed ESD safe practices when working with computers • Described the purpose and featurse of power supplies; and installed a new power supply into a PC • Resolved faulty power supply problems