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could you tell us how the PSU goes dead! i mean what exactly leads to the failure of the PSU?
as a start open it and check the Fuse (usually connected facing the fan .. ( the fuse might be blow up due to transient) did you connect it to a resistive load without shunt diodes?! or maybe you connect it to an external load which draws more current that it can supply.
PC power supplly will have two sections one is flyback converter serves as standby power used to turn ON main power, other one is PWM switch mode power supply serves multiple outputs. Standby power is 5V supply allways ON aslong as line power is available. using the colour code and pin details check the standby power availability (+5V SB- -colour purple wire). if stand by power is available try to power ON by shorting the green and black wire.
could you tell us how the PSU goes dead! i mean what exactly leads to the failure of the PSU?
as a start open it and check the Fuse (usually connected facing the fan .. ( the fuse might be blow up due to transient) did you connect it to a resistive load without shunt diodes?! or maybe you connect it to an external load which draws more current that it can supply.
as i switched my generator supply to the supply provided by the government with the help of change over (selector) the computer restarts and the PSU didn't start up and so did the computer
the PSU usually comes with voltage selector you can see it beside the power cable connector. it switches from 120 volt to 220 volt and vise versa. depends on your country electrical ratings. if your psu do not contain this selector so i guess you'll have to change it. (Much Cheaper than hacking it to supply ur desired voltage).
Hope that help. feel free to msg me if you need additional help.
the PSU usually comes with voltage selector you can see it beside the power cable connector. it switches from 120 volt to 220 volt and vise versa. depends on your country electrical ratings. if your psu do not contain this selector so i guess you'll have to change it. (Much Cheaper than hacking it to supply ur desired voltage).
Hope that help. feel free to msg me if you need additional help.
as i switched my generator supply to the supply provided by the government with the help of change over (selector) the computer restarts and the PSU didn't start up and so did the computer
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How the computer can start up while the psu does not.
I think when you put it to utility line 220v only Monitor/Lcd turned on and main/mother board did not.because there is no relation between the psu and Monitor/Lcd.They both have separate power supplies.
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So the voltage in our country is 230v.Almost all computers no matter brand new or used are sold with the switch set to 230v.So until you switch them to 120v,if so then don't even think about to repair it.It is a switching power supply.After all not the job for unexperienced people, you could get killed or injured if you touch high voltage parts inside.
Rectified DC voltage of 300v is much more dangerous than AC 230.
when it happened did you listen any bang or chirping sound or smoke or burning smell?
SMPS could die without any smoke or smell or bang.
There is always a fuse inside them,may have blown.
If the switch was set to 120v and PSu put to 220v, The fuse may have blown along with main filtering capacitor exploded or at least badly heated up and damaged.
PWM chip or Other PWM circuitry damaged.
And if not any of above conditions and switch is properly put to 230v setting then a sudden surge( mains voltage increased )could have killed the psu silently.And you could not know it (That happens sometimes in our country. Last year the voltage in my feeder line of "WAPDA" suddenly went to 440v And every appliance running in my home was damaged beyond repair).
Another reason could be just aging. Inside the psu are a number of Capacitors at the outputs of it.They can die with aging and Main board will not get a filtered voltages and may not start up or shut down shortly after startup.
This problem can be pointed out visually, by opening the PSU and without putting it to power.The top side of effected capacitor may look bulged or some leaked liquid electrolyte under the capacitor is sign of damaged capacitor.It happens to almost all cheap PSU.But the capacitor may not show any of above sign and still dead.
In every case mentioned above, you may not or should not try to open the PSU to repair it.Unless you have at least moderate level of experience in repairing mains operated circuits and have tools required to do so.
That should be enough for this topic(although it could be explained much longer) but no need to do so.
Long story short, throw it away and buy a new one good quality PSU.The repair cost will be much higher than the price of a good condition little used PSU.
First i must ask you your experience with electroics.
Have you tested the fuse.If not test it with multimeter.If it is in the socket take it out and if it is soldered to pcb just put one lead of multimeter on one end and the other on opposit end of fuse and read the resistance.There shall be no resistance.
If the fuse tests ok. Then look at the large 20 pin connector of PSU which is for Main board supply.There is a blue wire.Put a jumper wire in the the blue wire and the black wire next to it (creat the short circuit).Now put the psu to power and fan of psu should start to run.
If so then get the multimeter select 50vdc range ant start to test the voltages at the 20-pin connector.
Put the ground lead of multimeter to any of black wires and hold it there during entire test.Put red lead of multimeter to Orange wire of connector and it should read +3.3v
Red wire should read +5V.
Yellow +12v.
Purple +5v.
White -5v.
blue -12v.
gray wire is for power good signal.
If you find all the voltages good, Then you may want to test the supply by putting some load at it.And see if it shuts down or keep running.
If it keeps running them there may be problem with you main board short circuit in any of attached accessories or hardware.Then you must take it to a professional repairman.
First i must ask you your experience with electroics.
Have you tested the fuse.If not test it with multimeter.If it is in the socket take it out and if it is soldered to pcb just put one lead of multimeter on one end and the other on opposit end of fuse and read the resistance.There shall be no resistance.
If the fuse tests ok. Then look at the large 20 pin connector of PSU which is for Main board supply.There is a blue wire.Put a jumper wire in the the blue wire and the black wire next to it (creat the short circuit).Now put the psu to power and fan of psu should start to run.
If so then get the multimeter select 50vdc range ant start to test the voltages at the 20-pin connector.
Put the ground lead of multimeter to any of black wires and hold it there during entire test.Put red lead of multimeter to Orange wire of connector and it should read +3.3v
Red wire should read +5V.
Yellow +12v.
Purple +5v.
White -5v.
blue -12v.
gray wire is for power good signal.
If you find all the voltages good, Then you may want to test the supply by putting some load at it.And see if it shuts down or keep running.
If it keeps running them there may be problem with you main board short circuit in any of attached accessories or hardware.Then you must take it to a professional repairman.
as i swapped in a good PSU , my pc is working properly ..... it means my PSU (Dell PSU) is gone dead ..... fuse is working fine ..... i have checked with multimeter .... it gives proper reading ......
So your previous one was faulty.You swapped it with a new one and the previous one is going to sit in junk yard for some time and then shipped to china where it will be torn away and they will recycle it.May be some day most of its parts are coming back to market in some thing entirely different or they may just repair it clean it polish it and send it back to market as a new piece of PSU.
Anyway your problem is solved.Good luck with your new PSU.
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