Electricity and Power Supplies

1. ELECTRICITY AND POWER SUPPLIES Chapter 5

2. BASIC ELECTRICITY SUPPLIES To become a successful PC technician you need to understand electricity, know how to use it, how it’s measured and how to protect computer equipment from its damaging power. Basic term related to electricity:- Unit Definition Computer Example Volt (ex- 110 V) A measure of electricity “pressure” differential. An AT power supply provides four separate voltages: +12 V, -12 V, +5 V, and -5 V. Amp or ampere (ex- 1.5 A) A measure of electricity current. An 17-in monitor requires less than 2 A to operate. Ohm (ex- 20  ) A measure of resistance to electricity. Current can flow in typical computer cables and wires with a resistance on near zero  (ohm) Watt ( ex- 20 W) A measure of electricity power. A computer power supply is rated at 200 to 600 W.

4. SOME COMMON ELECTRONIC COMPONENTS Is an electronic device that can serve as a gate or switch for an electrical signal and can amplify the flow of electricity. Is an electronic device that can hold an electrical charge for a period of time and can smooth the uneven flow of electricity through a circuit. Is a semiconductor device that allows electricity to flow in only one direction. Is an electronic device that limits the amount of current that can flow through it.

5. TROUBLESHOOTING THE ELECTRICAL SYSTEM “ Your friend Sharon calls to ask you help with a computer problem. Her system has been working fine for ever a year, but now strange things are happening. Sometimes the system powers down while she is working for no apparent reason and sometimes Windows locks up.

7. PROBLEM WITH THE POWER SUPPLY A brownout of the house current. Loose connections inside the computer can cause a system to appear dead or reboot itself. Problems with external power Problems with loose internal connections

10. HOW TO DIAGNOSE POWER SUPPLY PROBLEMS

11. PROTECTING YOUR COMPUTER SYSTEM