Troubleshooting Power Supply Units (PSUs).

Troubleshooting Power Supply Units (PSUs).


Among all the PC components,the power supplyis the most dangerous.


It convertsthe240V walvoltage into smaler12V, 5V and 3.3V DC allocations required by thePC. Usualy, the power supply comeswith the cabinet and is backed by a warrantyso   shouldn’t haveproblems.


*     However ,itpays to be careful and take theextra effort to verify the quality of the powersupply.


*     If  purchasing it separately, opt for a brandname. Check around with yourfriends ,the Internet and other system APSU with allits connectors builders.


*    Horror storiesoffaulty PSUs that blow up and ruin entire PCs are common.


*    A good qualityPSUwill not only give  system a long lifespan,it will also help reduce thenoise and heat generated inside the cabinet.


 Some commonproblems   with PSUs are:



 The power doesn’t come on


1.     No power from thewalsocket :

*    Use a live poweroutlet .

*    In rare cases, thepower cable may be defective and may require replacement.

*     Check thepower cable on another working PC.


2.     Incorrectvoltageseting on thePSU:

*    Select the propervoltage setting (220-240V)on the back of the PSU.


*    WARNING: If switched on the PC with the voltage set to10-120V and with a mains supply of240V  mayhave blown   PSU beyond repair at worst or blown a fuseatbest.


  3.The front panel power switch’s connectortothe   mother board Is not fixed correctlyor has come of or isdefective :


*    Check the mother boardmanual and fix the lead (wires) from the front panel switch to the mother boardcorrectly.

*     If there isstill no power , try a different lead.


4.The front panelpower switch is defective:

*    Replace theswitch.

*    If   donot want to get a replacement ,one optionis to use the reset button.

*    The only problemwiththis is that to cut the power to the system in case of system hang setc. ,thenswitch of the power from the mains wall outlet rather than from the front panel.

5. The power supplyconnections to the mother board arenotcorrect:


*    Check thepowerconnections from the PSU to the motherboard.

*    Refer to themotherboard manual and identify the correct connection points.


6. Notidentified; non-PSU related problem:

*    After attemptingallthe above, if the system still doesn’t power up ,it is time to look else where.

*    Disconnect allthedrives and se if it is powering up.

*    If the systemispowering up,then start reconnecting the drives one by one to identify whichis defectivedrive.

*    If the system isnotpowering with all drives disconnected, remove the other adaptors neat a timeandchecking to see if it is power in gup .

*    Leave the videoadapt or for the last.

*    If the system isstillnot powering up, then you either have a defective PSU or adefectivemotherboard.

*     If there is aburnt smell, then most probablyeither one of them has been fried.

*    Look for burnmarkson the motherboard.

*     Sometimes thePSU and motherboard may be incompatible.

*    If them otherboardlooks fine, replace the PSU, sinceit’s cheaper.



 The PC powers on after the second or third try


*    The mostlylikelyproblem is that the power ok(or power good) signals sent be fore thepower supplyhas stabilized.

*    Get a betterqualityPSU.

*    In modern PCs,thepower switch is a logic device that tells the PSU to supply full power tothe motherboard.

*    The power oksignaltells the motherboard that the power supply is available and stable.

*    If the signalssenttoo soon the motherboard doesn’t recognize it and stays of to protectitself.

*    This can happenin lowerquality PSUs.

*    Booting morethanonce is not recommended, and   will be better of getin   beter PSU.



 The PCpowers on but nothing happensafterthat(nobeep) 


*    This may be duetothe addition of new hardware that is over-taxing the power supply. Removethelast hardware component instaled and check again.

*     A defectiveharddisk or one that is notplugedin corectly: Check the power cable to theharddisk.

*    Sometimes it maynotbe fuly pluged in.

*    Check the harddiskon another system.



 The PC freezes or reboots suddenly


*    1.This couldindicateafailing PSU that is not supplying power correctly to the motherboard.

*    You may be abletoget the PSU serviced but in most cases  be better   ofgetting a new powersupply.

*    This could be duetoover heating of the PSU or CPU: If the PSU is over heating ,the metalcabinetmay be hot to touch or  might geta shock.

*    Shut ofimmediately.Check if the PSU fan is working, clean or replace the fan if notworking or spinningvery slowly.

*     If it’s afaulty PSU   may beable to service









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