See How To Troubleshoot Your Power Supply

by : Otis F. Cooper

The Power Supply convert's your regular household
current into low DC voltage used by the computer.
When this component fails,there is simply no activity
going on wih your computer.Remember to do the
easy troubleshooting first.Inspect the Power Supply
for any damage.Double-Check all connections.

Learning how to check your power supply and how to
replace it when needed can be a life saver if you're a
computer buff or in business with the trusted PC.Don't
take for granted the simple pleasure of turning on your
PC and everything works just fine.

We turned on one of our computers recently and in about
one hour,it just re-booted itself.And it continued doing so
about 10 times a day until we found out the power supply
was the culprit.Things to look for when your power supply
is going bad or just dies on you are the following.


Here you must first check the wall outlet for power
by connecting another device such as a radio or
lamp to be sure power is present.If the computer
is connected through a surge protector,check it
as well.

If the wall out has power,check the power cable
going to the PC to see if AC voltage is making
its way to the system unit.Do this with the use of
a multimeter.

If there is power,you will have to open the PC
and check for power from the power supply to the

When using a multimeter to check voltage,be sure
you have a good ground for the black lead of the


One main problem you may face with an ailing Power
Supply is that it may re-boot the computer without any
warning.All information is lost and it seems as though
this happens at the worst possible time.

Booting errors when the computer first start's up is
another indicator of this component going on the blink.


When the power supply begins to fail,you may receive
power at one device and not another.For example,the
Hard Drive may receive power but the CDROM Drive
has nothing at all.

Another headache with would cause re-booting is the
intermittent power going to the drives or the motherboard
itself.Follow the steps below to check your power supply
should you experience some of the above problems.


If the wall outlet,and the power cord are good,make sure
the connection at the motherboard is secure.Then you
may have to face the fact that the power supply itself is
bad.If you have a Multimeter you can test the power supply
output before purchasing a new one.Simply follow these steps.

Turn off the PC,but do not unplug it,open the system unit.
Set the multimeter to read DC volts in the next range higher
than 12 volts.Locate a power connector similair to the hard
drive,or cdrom drive connector that is unused and turn on
the PC.

You can also unplug a drive connector and use it as
well.Turn on the PC and insert the BLACK probe into the
power connector on one of the BLACK wires.Touch the
RED probe to the YELLOW wire on the power connector.

The multimeter reading should be +12 volts Now touch
the RED probe to the RED wire and the reading should be
+5 volts.If no readings or different readings occured,you'll have
to replace the power supply.If the readings were correct,you
should check the P8 or P9 connectors at the motherboard.
These connectors may also be named P4 and P5.To check
these connectors,perform the following...

Insert the BLACK probe into P8 at one of the BLACK wires.
Insert the RED probe into the P8 connector at the RED wire.
The reading on the multimeter should be +5 volts

Check the power going to the Motherboard connections
by inserting the RED probe into P8 at the YELLOW wire and
you should get +12 volts.Leave the BLACK wire touching the
black wire at the P8 connector.Check the BLUE wire and the
reading should be a -12 volts.

Now move the BLACK probe to the BLACK wire on the P9
connector.Test the WHITE wire by inserting the RED probe and
the reading should be -5 volts.Check the RED wires on the P9
connector and you should get +5 volts on each red wire.You
won't get exactly 5 or 12 volts but the readings will be very close,
such as 5.02 volts.

If the Power Supply is a couple of volts off,in either direction,such
as when the RED wire should be reading -5 volts but it reads -8
volts,or if there are no readings,replace the power supply.

DO NOT remove the power supply from the system unit case
when performing these tests.DO NOT perform these tests if
you do not feel comfortable.Be sure to remove any and all electrical
static build-up from your clothes and body BEFORE touching
any parts inside the system unit.And NEVER open the power
supply case for any reasonHealth Fitness Articles,since high voltage may be present.