Course ILT 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

Course ILT Topic A Topic A: Electricity and electronics Topic B: Static electricity Topic C: Power supplies Topic D: Power supply troubleshooting

Course ILT Electricity characteristics Voltage Current Alternating or direct current Resistance and impedance Power and energy

Course ILT Activity A-1 Examining the characteristics of electricity

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

Course ILT 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

Course ILT Activity A-2 Considering electrical safety

Course ILT Digital multimeter

Course ILT Analog multimeter

Course ILT Using a multimeter Measuring resistance Measuring voltage Measuring current Measuring continuity

Course ILT Activity A-3 Measuring electrical values

Course ILT Topic B Topic A: Electricity and electronics Topic B: Static electricity Topic C: Power supplies Topic D: Power supply troubleshooting

Course ILT 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

Course ILT 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

Course ILT 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

Course ILT Static wrist strap

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

Course ILT Slide catches Slide catch, move to open side of case

Course ILT Determining which side to open Ports and connectors attached to motherboard Open this side to access components

Course ILT Removable front cover Alignment posts Alignment holes Spring catches

Course ILT Activity B-1 Opening the computer case while following proper ESD precautions

Course ILT Topic C Topic A: Electricity and electronics Topic B: Static electricity Topic C: Power supplies Topic D: Power supply troubleshooting

Course ILT A PC power supply

Course ILT Voltage selection switch

Course ILT Typical power requirements Motherboard30 W Memory10 W / 128 MB CPU65 W or more Hard drive5 – 15 W CD-ROM drive10 – 20 W Floppy drive5 – 10 W Adapter card5 – 30 W

Course ILT Standard outputs +3.3 V14 AAGP video cards, motherboard -5 V0.3 AISA bus adapter cards +5 V30 AMotherboard, CD/DVD drives, hard drives, PCI adapter cards, Pentium III and earlier processors +5 V0.85 A“Soft power” switch -12 V1 AOlder network adapters and serial ports +12 V12 ACD/DVD drives, hard drives, Pentium 4 and Athlon processors, motherboard

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

Course ILT Peripheral power connector “Molex” connector

Course ILT Floppy power connector “Berg” connector

Course ILT SATA power connector New, for Serial ATA drives

Course ILT Wire colors Yellow = +12 V Red = +5 V Black = ground

Course ILT Motherboard power connectors

Course ILT Power supply form factors ATX/NLX150 x 140 x 86 millimeters 486 and Pentium PCs First with soft- power switch and 3.3V SFX100 x 125 x 63.5 millimeters Pentium PCsNo -5 V output for ISA cards WTX150 x 230 x 86 (single fan) 224 x 230 x 86 (double fan) Pentium PCsNo -5 V output for ISA cards

Course ILT Activity C-1 Examining a power supply and connectors

Course ILT Topic D Topic A: Electricity and electronics Topic B: Static electricity Topic C: Power supplies Topic D: Power supply troubleshooting

Course ILT 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

Course ILT Activity D-1 Troubleshooting power supply problems

Course ILT 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