Power Supply

Power Supply
Supplies power throughout the computer. Power supplies converts potentially lethal 115 or 230 volt alternating current (AC) into a steady low-voltage direct current (DC) usable by the computer

A typical PC needs about 500W

AC - alternating current comes from the outlet
DC - direct current goes to the PC
Electrons - A flow of negatively charged particles called electrons

Electricity

Volts - 110-115v in USA Other countries use 220-230v (pressure)

Amperes - the number of electrons per second flowing between two points the amount of water per sec. leaving a dam thru a pipe (the higher the amount the more dangerous)

Watts - Amount of power (typical PC today use about 500 watts)

Ohms - Resistance (Ω) Impedance

Two types of Power supply

AT and ATX power supply

ATX has a special power soft switch that can enable the PC to go into suspend or sleep mode

AT uses the P8 and P9 as the main connectors where it connects to the
AT socket of the motherboard



When installing P8/P9 black wires which represent ground must face each other and clips face out

ATX uses the P1 power connector and goes directly into the ATX socket
P1 can either be 20 or 24pins for the newer computers

Note some P1 also have a P4 connector (12v)

P6, P8 and P12 connectors as add ons

Power Supply Connectors

Berg or Mini Connector connects to a Floppy Drive

Molex 4 pin and SATA 15 pin connector connects to the following devices:

CD ROM
CD R
CD RW
DVD ROM
DVD R
DVD RW
Blu Ray
HD DVD
Hard Drive
SCSI Devices
Tape Drive
Zip Drive
Cooling Fan
Video Card

Troubleshooting a Power Supply

It is Plugged In
Check Connection
It is Turn on
Check AC Outlet
Check surge protector or UPS Connection
Check On and Off Switch on back of PC
Check Front Panel connectors
Check Voltage
Check Motherboard power sockets if its good or not. 
Check for Dust
Check Cooling Fan
Overheating is it hot?
Check for weird and unusual noises
Power Supply should have a quiet humming noise if it’s good
Check for erratic behavior and long shut downs

To Test a Power Supply use the following:

Multimeter



Volt Meter


Power Supply Tester

(if the power supply is bad then replace it)