 Mr. RAJ’s Computer Repair I & II: A+ ESSENTIALS (701) & Computer Repair III & IV Practical Applications (702) Contact: Online Exams: Wiki & Notes: Designed and prepared for Mr. Raj Students Only at Career Technical Institute [Confidential] Note: Do not copy or distribute without Mr. Raj’s Authorization! Unit II: Lets discuss the Electricity/ Power Supplies! Rajeev Gupta (Mr. RAJ) 15 Years of IT & Training Experience in Hardware and Networking. Training is my Passion. I am really excited about brining this information to you. I will do my best to give you a perfect place to launch an IT career and I promise it will help you tremendously in knowing how the PC works. You will be building on the foundation no matter where you go. 1

 Mr. RAJ’s Computer Repair I & II: A+ ESSENTIALS (701) & Computer Repair III & IV Practical Applications (702) Contact: Online Exams: Wiki & Notes: Designed and prepared for Mr. Raj Students Only at Career Technical Institute [Confidential] Note: Do not copy or distribute without Mr. Raj’s Authorization! Electricity and power supplies Unit objectives: Identify electrostatic discharge, and follow ESD safe practices while working with computer components Install a new power supply in a PC Troubleshoot faulty power supplies

 Mr. RAJ’s Computer Repair I & II: A+ ESSENTIALS (701) & Computer Repair III & IV Practical Applications (702) Contact: Online Exams: Wiki & Notes: Designed and prepared for Mr. Raj Students Only at Career Technical Institute [Confidential] Note: Do not copy or distribute without Mr. Raj’s Authorization! AC/DC Not an 80’s heavy metal band! DC AC A DC current flows in one direction An AC current flows in both directions The PC’s PSU converts high voltage (230V) AC supplied by the ESB to low voltage DC required by the PC’s motherboard and components

 Mr. RAJ’s Computer Repair I & II: A+ ESSENTIALS (701) & Computer Repair III & IV Practical Applications (702) Contact: Online Exams: Wiki & Notes: Designed and prepared for Mr. Raj Students Only at Career Technical Institute [Confidential] Note: Do not copy or distribute without Mr. Raj’s Authorization! 115/230 switch Exam! Used to switch the PSU between 115 volts and 230 volts

 Mr. RAJ’s Computer Repair I & II: A+ ESSENTIALS (701) & Computer Repair III & IV Practical Applications (702) Contact: Online Exams: Wiki & Notes: Designed and prepared for Mr. Raj Students Only at Career Technical Institute [Confidential] Note: Do not copy or distribute without Mr. Raj’s Authorization! Topic A Topic A: Electrical safety Topic B: Power supplies Topic C: Power supply troubleshooting

 Mr. RAJ’s Computer Repair I & II: A+ ESSENTIALS (701) & Computer Repair III & IV Practical Applications (702) Contact: Online Exams: Wiki & Notes: Designed and prepared for Mr. Raj Students Only at Career Technical Institute [Confidential] Note: Do not copy or distribute without Mr. Raj’s Authorization! Characteristics of electricity Electricity — Flow of electrons Conductor — Permits flow of electricity Insulator — Inhibits flow of electricity Voltage — Force of electricity caused by difference in charge at two locations – Measured in volts – Also called “potential” or “potential difference” – Officially designated as uppercase V – May see it as lowercase v continued

 Mr. RAJ’s Computer Repair I & II: A+ ESSENTIALS (701) & Computer Repair III & IV Practical Applications (702) Contact: Online Exams: Wiki & Notes: Designed and prepared for Mr. Raj Students Only at Career Technical Institute [Confidential] Note: Do not copy or distribute without Mr. Raj’s Authorization! Characteristics, continued Current — Measure of the flow of electrons past a given point – Measured in amps, or amperes – Must be a complete circuit (closed circuit) – Direct current — Flows in one direction, at constant voltage, through circuit – Alternating current — Flows repeatedly back and forth through the circuit, at constantly varying voltage levels continued

 Mr. RAJ’s Computer Repair I & II: A+ ESSENTIALS (701) & Computer Repair III & IV Practical Applications (702) Contact: Online Exams: Wiki & Notes: Designed and prepared for Mr. Raj Students Only at Career Technical Institute [Confidential] Note: Do not copy or distribute without Mr. Raj’s Authorization! Characteristics, continued Resistance — Force that opposes the flow of DC through a conductor – Measured in ohms (Ω) Impedance — Like resistance, but applies to AC Power – Measured in watts – Calculate by multiplying voltage by current Energy — Electrical power delivered over time

 Mr. RAJ’s Computer Repair I & II: A+ ESSENTIALS (701) & Computer Repair III & IV Practical Applications (702) Contact: Online Exams: Wiki & Notes: Designed and prepared for Mr. Raj Students Only at Career Technical Institute [Confidential] Note: Do not copy or distribute without Mr. Raj’s Authorization! Electricity Current can kill The 1–10–100 rule Calculating current V = i * r Resistance of the human body is about 500 KΩ (500,000 Ω)

 Mr. RAJ’s Computer Repair I & II: A+ ESSENTIALS (701) & Computer Repair III & IV Practical Applications (702) Contact: Online Exams: Wiki & Notes: Designed and prepared for Mr. Raj Students Only at Career Technical Institute [Confidential] Note: Do not copy or distribute without Mr. Raj’s Authorization! Safety precautions Don’t touch exposed contacts Touch only insulated handles of tools Leave covers on equipment Work one-handed Don’t insert anything into wall outlets Remove jewelry, watches, etc. Keep hands clean and dry Don’t work in wet surroundings

 Mr. RAJ’s Computer Repair I & II: A+ ESSENTIALS (701) & Computer Repair III & IV Practical Applications (702) Contact: Online Exams: Wiki & Notes: Designed and prepared for Mr. Raj Students Only at Career Technical Institute [Confidential] Note: Do not copy or distribute without Mr. Raj’s Authorization! Electrostatic discharge (ESD) Buildup of charges Static dangers Discharge voltages – volts to feel – volts to see spark – 35,000 volts on a dry day on carpet – 1000 volts can damage electronics

 Mr. RAJ’s Computer Repair I & II: A+ ESSENTIALS (701) & Computer Repair III & IV Practical Applications (702) Contact: Online Exams: Wiki & Notes: Designed and prepared for Mr. Raj Students Only at Career Technical Institute [Confidential] Note: Do not copy or distribute without Mr. Raj’s Authorization! Preventing static buildup Don’t shuffle your feet Increase the humidity Keep yourself grounded Wear cotton, not synthetics Remove carpeting Use air ionization system Design Tech Support Room well Discharge static build-up Anti-static strap Anti-static mat Don’t place components on metal surfaces Anti-static bags

 Mr. RAJ’s Computer Repair I & II: A+ ESSENTIALS (701) & Computer Repair III & IV Practical Applications (702) Contact: Online Exams: Wiki & Notes: Designed and prepared for Mr. Raj Students Only at Career Technical Institute [Confidential] Note: Do not copy or distribute without Mr. Raj’s Authorization! Preventing static discharge Equalize charge differences safely – Unplug the equipment – Touch its metal chassis or power supply Keep yourself and equipment connected – Wrist straps and antistatic mats – Static-safe bags

 Mr. RAJ’s Computer Repair I & II: A+ ESSENTIALS (701) & Computer Repair III & IV Practical Applications (702) Contact: Online Exams: Wiki & Notes: Designed and prepared for Mr. Raj Students Only at Career Technical Institute [Confidential] Note: Do not copy or distribute without Mr. Raj’s Authorization! Power Terms Joules (J) = Energy Volts (V) = Voltage (pressure of electrons in the wire) Amps (A) = Current (amount of electrons moving past a certain point in the wire) Watts (W) = Measure of power (how many amps and volts a device needs to work) Ohms (Ω) = resistance (how much the wire resists the flow of electrons)

 Mr. RAJ’s Computer Repair I & II: A+ ESSENTIALS (701) & Computer Repair III & IV Practical Applications (702) Contact: Online Exams: Wiki & Notes: Designed and prepared for Mr. Raj Students Only at Career Technical Institute [Confidential] Note: Do not copy or distribute without Mr. Raj’s Authorization! Surge Suppressors Protects PC from voltage spikes Between PC and wall socket At least Joule(J) rating Joule = a measure of energy A higher joule rating means you can be protected from a more powerful power surge

 Mr. RAJ’s Computer Repair I & II: A+ ESSENTIALS (701) & Computer Repair III & IV Practical Applications (702) Contact: Online Exams: Wiki & Notes: Designed and prepared for Mr. Raj Students Only at Career Technical Institute [Confidential] Note: Do not copy or distribute without Mr. Raj’s Authorization! UPS Uninterruptable Power Supply Protects PC from brownouts and blackouts Two types: Online (UPS) and Standby (SPS) Most UPSs include surge suppressors Essentially a sophisticated and big battery Rated in Watts NB. Never connect a printer to a UPS Exam!

 Mr. RAJ’s Computer Repair I & II: A+ ESSENTIALS (701) & Computer Repair III & IV Practical Applications (702) Contact: Online Exams: Wiki & Notes: Designed and prepared for Mr. Raj Students Only at Career Technical Institute [Confidential] Note: Do not copy or distribute without Mr. Raj’s Authorization! UPS Wall Socket Sockets PC

 Mr. RAJ’s Computer Repair I & II: A+ ESSENTIALS (701) & Computer Repair III & IV Practical Applications (702) Contact: Online Exams: Wiki & Notes: Designed and prepared for Mr. Raj Students Only at Career Technical Institute [Confidential] Note: Do not copy or distribute without Mr. Raj’s Authorization! Power Terms - Summary Pressure = Voltage (V) Volume Flowing = Amperes (A) Work = Wattage (W) Resistance = Ohms (Ω) Fuses and Ground Wires An electrical outlet must have a ground wire to be suitable for PC use Exam!

 Mr. RAJ’s Computer Repair I & II: A+ ESSENTIALS (701) & Computer Repair III & IV Practical Applications (702) Contact: Online Exams: Wiki & Notes: Designed and prepared for Mr. Raj Students Only at Career Technical Institute [Confidential] Note: Do not copy or distribute without Mr. Raj’s Authorization! Topic B Topic A: Electrical safety Topic B: Power supplies Topic C: Power supply troubleshooting

 Mr. RAJ’s Computer Repair I & II: A+ ESSENTIALS (701) & Computer Repair III & IV Practical Applications (702) Contact: Online Exams: Wiki & Notes: Designed and prepared for Mr. Raj Students Only at Career Technical Institute [Confidential] Note: Do not copy or distribute without Mr. Raj’s Authorization! Voltage selection switch Set power supply to run on 110 V or 220 V With computer off, slide switch Usually located near power cord port

 Mr. RAJ’s Computer Repair I & II: A+ ESSENTIALS (701) & Computer Repair III & IV Practical Applications (702) Contact: Online Exams: Wiki & Notes: Designed and prepared for Mr. Raj Students Only at Career Technical Institute [Confidential] Note: Do not copy or distribute without Mr. Raj’s Authorization!

 Mr. RAJ’s Computer Repair I & II: A+ ESSENTIALS (701) & Computer Repair III & IV Practical Applications (702) Contact: Online Exams: Wiki & Notes: Designed and prepared for Mr. Raj Students Only at Career Technical Institute [Confidential] Note: Do not copy or distribute without Mr. Raj’s Authorization! Power supply specifications Rated by DC power output in watts –Modern systems typically =>300 watts –Older systems <200 watts Rating isn’t an indicator of power draw –Draws only the power needed to supply internal components

 Mr. RAJ’s Computer Repair I & II: A+ ESSENTIALS (701) & Computer Repair III & IV Practical Applications (702) Contact: Online Exams: Wiki & Notes: Designed and prepared for Mr. Raj Students Only at Career Technical Institute [Confidential] Note: Do not copy or distribute without Mr. Raj’s Authorization! Typical power requirements Motherboard30 W Memory10 W per 2 GB* CPU45–145 W or more Hard drive5–15 W CD-ROM drive5–20 W Floppy drive5–10 W Adapter card5–30 W

 Mr. RAJ’s Computer Repair I & II: A+ ESSENTIALS (701) & Computer Repair III & IV Practical Applications (702) Contact: Online Exams: Wiki & Notes: Designed and prepared for Mr. Raj Students Only at Career Technical Institute [Confidential] Note: Do not copy or distribute without Mr. Raj’s Authorization! 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

 Mr. RAJ’s Computer Repair I & II: A+ ESSENTIALS (701) & Computer Repair III & IV Practical Applications (702) Contact: Online Exams: Wiki & Notes: Designed and prepared for Mr. Raj Students Only at Career Technical Institute [Confidential] Note: Do not copy or distribute without Mr. Raj’s Authorization! Power connectors Two standards –Drive power connectors –Motherboard power connectors Yellow = +12 V Red = +5 V Black = ground

 Mr. RAJ’s Computer Repair I & II: A+ ESSENTIALS (701) & Computer Repair III & IV Practical Applications (702) Contact: Online Exams: Wiki & Notes: Designed and prepared for Mr. Raj Students Only at Career Technical Institute [Confidential] Note: Do not copy or distribute without Mr. Raj’s Authorization! Motherboard power connectors Dual power connectors Single power connector

 Mr. RAJ’s Computer Repair I & II: A+ ESSENTIALS (701) & Computer Repair III & IV Practical Applications (702) Contact: Online Exams: Wiki & Notes: Designed and prepared for Mr. Raj Students Only at Career Technical Institute [Confidential] Note: Do not copy or distribute without Mr. Raj’s Authorization! Power supply form factors Describes size and shape Must fit: – Case – Motherboard – Other components  Motherboard_form_factor

 Mr. RAJ’s Computer Repair I & II: A+ ESSENTIALS (701) & Computer Repair III & IV Practical Applications (702) Contact: Online Exams: Wiki & Notes: Designed and prepared for Mr. Raj Students Only at Career Technical Institute [Confidential] Note: Do not copy or distribute without Mr. Raj’s Authorization! Wire colors 20-pin ATX v1.0 single motherboard connector 24-pin ATX v2.0 motherboard connector PSU - AT P8 + P9 Black to Black with the black wires in the centre AT power switch Doesn’t support hibernate mode Wake on modem/LAN not supported

 Mr. RAJ’s Computer Repair I & II: A+ ESSENTIALS (701) & Computer Repair III & IV Practical Applications (702) Contact: Online Exams: Wiki & Notes: Designed and prepared for Mr. Raj Students Only at Career Technical Institute [Confidential] Note: Do not copy or distribute without Mr. Raj’s Authorization! PSU - ATX Replaced the AT PSU Used with ATX case and motherboard P1 power connector Supplies +3.3V / +2.8V to motherboard Can’t use an AT PSU with an ATX motherboard and vice versa “Soft Power” Constantly supplies 5V to the PC Never off Separate on/off switch

 Mr. RAJ’s Computer Repair I & II: A+ ESSENTIALS (701) & Computer Repair III & IV Practical Applications (702) Contact: Online Exams: Wiki & Notes: Designed and prepared for Mr. Raj Students Only at Career Technical Institute [Confidential] Note: Do not copy or distribute without Mr. Raj’s Authorization! Installing a power supply 1.Shut down computer 2.Unplug computer 3.Remove cover from computer 4.Disconnect all power wires from components, including motherboard 5.Remove retaining screws 6.Remove power supply 7.Install new power supply and screw it into place 8.Connect power wires to components as needed, including motherboard 9.Replace cover 10.Plug computer into outlet, and boot system to test your work

 Mr. RAJ’s Computer Repair I & II: A+ ESSENTIALS (701) & Computer Repair III & IV Practical Applications (702) Contact: Online Exams: Wiki & Notes: Designed and prepared for Mr. Raj Students Only at Career Technical Institute [Confidential] Note: Do not copy or distribute without Mr. Raj’s Authorization! Function of the PSU Converts 230V AC to +5V –5V and +12V – 12V DC Changes from AC to DC Smoothes out power sags and spikes Also helps to cool the PC components

 Mr. RAJ’s Computer Repair I & II: A+ ESSENTIALS (701) & Computer Repair III & IV Practical Applications (702) Contact: Online Exams: Wiki & Notes: Designed and prepared for Mr. Raj Students Only at Career Technical Institute [Confidential] Note: Do not copy or distribute without Mr. Raj’s Authorization! Topic C Topic A: Electrical safety Topic B: Power supplies Topic C: Power supply troubleshooting

 Mr. RAJ’s Computer Repair I & II: A+ ESSENTIALS (701) & Computer Repair III & IV Practical Applications (702) Contact: Online Exams: Wiki & Notes: Designed and prepared for Mr. Raj Students Only at Career Technical Institute [Confidential] Note: Do not copy or distribute without Mr. Raj’s Authorization! Electrical measurements Measure electrical values with a multimeter Multimeters can be digital or analog Use to measure – Resistance – Voltage – Current – Continuity

 Mr. RAJ’s Computer Repair I & II: A+ ESSENTIALS (701) & Computer Repair III & IV Practical Applications (702) Contact: Online Exams: Wiki & Notes: Designed and prepared for Mr. Raj Students Only at Career Technical Institute [Confidential] Note: Do not copy or distribute without Mr. Raj’s Authorization! Measuring resistance 1.Turn off the device you’re measuring and disconnect it from its power source 2.You might need to disconnect the device from its circuit 3.Set the multimeter to read resistance 4.Touch the two leads of the multimeter together 5.Touch the black and red probes to either side of the circuit to be measured 6.Read the resistance from the meter’s display

 Mr. RAJ’s Computer Repair I & II: A+ ESSENTIALS (701) & Computer Repair III & IV Practical Applications (702) Contact: Online Exams: Wiki & Notes: Designed and prepared for Mr. Raj Students Only at Career Technical Institute [Confidential] Note: Do not copy or distribute without Mr. Raj’s Authorization! Measuring voltage 1.Verify the power supply is on 2.Set your multimeter to read either DC or AC voltage 3.Touch the black probe to the ground, and touch the red probe to the spot where you want to measure the voltage 4.Read the voltage from the meter’s display You must exercise care when taking voltage readings as the computer is powered up

 Mr. RAJ’s Computer Repair I & II: A+ ESSENTIALS (701) & Computer Repair III & IV Practical Applications (702) Contact: Online Exams: Wiki & Notes: Designed and prepared for Mr. Raj Students Only at Career Technical Institute [Confidential] Note: Do not copy or distribute without Mr. Raj’s Authorization! Measuring current Break the circuit and insert the meter in the break Ammeter doesn’t require break Clamp ammeters are often used to measure current flow in 110 V and higher circuits

 Mr. RAJ’s Computer Repair I & II: A+ ESSENTIALS (701) & Computer Repair III & IV Practical Applications (702) Contact: Online Exams: Wiki & Notes: Designed and prepared for Mr. Raj Students Only at Career Technical Institute [Confidential] Note: Do not copy or distribute without Mr. Raj’s Authorization! Measuring continuity Set your multimeter to display resistance (ohms) and look for circuits with zero resistance Also can use continuity mode, if available

 Mr. RAJ’s Computer Repair I & II: A+ ESSENTIALS (701) & Computer Repair III & IV Practical Applications (702) Contact: Online Exams: Wiki & Notes: Designed and prepared for Mr. Raj Students Only at Career Technical Institute [Confidential] Note: Do not copy or distribute without Mr. Raj’s Authorization! Power supply problems Computer fails to boot when powered on, but boots after Ctrl+Alt+Del Computer intermittently stops working or reboots You don’t have enough power connectors for all the devices you want to install Computer fails to boot at all (no lights or beeps); fans don’t start Computer fails to boot, but fans start

 Mr. RAJ’s Computer Repair I & II: A+ ESSENTIALS (701) & Computer Repair III & IV Practical Applications (702) Contact: Online Exams: Wiki & Notes: Designed and prepared for Mr. Raj Students Only at Career Technical Institute [Confidential] Note: Do not copy or distribute without Mr. Raj’s Authorization! The Power_Good signal Signals CPU that power is stable and sufficient +5 V over specific wire Must arrive at correct time

 Mr. RAJ’s Computer Repair I & II: A+ ESSENTIALS (701) & Computer Repair III & IV Practical Applications (702) Contact: Online Exams: Wiki & Notes: Designed and prepared for Mr. Raj Students Only at Career Technical Institute [Confidential] Note: Do not copy or distribute without Mr. Raj’s Authorization! Unit summary Identified electrostatic discharge, and followed ESD safe practices while working with computer components Installed a new power supply in a PC Identified and resolved issues with faulty power supplies