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ATX SMPS Test
By Jestine Yong on September 5, 2007
ATX SMPS Test is very easy. Just use a scrap motherboard and connect the power supply onto it and place a wire across the two pins shown in the picture below in order to turn the ATX power supply “On”. If possible place two more harddisk to act as load just incase the single motherboard load not enough to switch it on. The symptom could be the fan rotate for a while and then totally stop!
Be cautious that not all ATX power supply support all kinds of motherboard. Some power supply just need back its own motherboard or system in order to function properly. Hope after reading this tips you should not have any more problem for ATX SMPS Test.
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admin
October 12, 2009 at 8:23 pm
Hi Abdul,
Yes it could be power shortage. You can always use a higher watt power supply to test it out. The 4 Pin Molex P4 12V Power Connector is use specifically for Pentium 4 Processor Motherboards while the 6 Pin AUX power connector was added to provide extra wattage to motherboards for 3.3 and 5 volts. Does the power supply have the 6 pin AUX power connector? This connector is rarely used anymore. It's most commonly found on older dual CPU AMD motherboards.
Abdul Haseeb
October 12, 2009 at 11:17 pm
Hi Jestine,
Thanx a lot for clarifying my doubt which has had me puzzled for long. 🙂 My SMPS does not have any 6 pin connector. It has one 10x2(20-pin)(connected), two 2x2(only one connected as i mentioned earlier), four 4x1(all connected to HDDs and DVD Writer) and one floppy connector(disconnected). Also, i use the Pentium Dual Core 2.6Ghz Processor. So, do you think i should connect the 4-pin connector in the left out 4 pins? Will it help me in any way?
Thanx!
admin
October 13, 2009 at 7:27 pm
Hi Abdul,
I'm not sure about that. May be try to disable two of the internal HDD and see how it goes first. By the way when you said your system does not read at all, does it mean it just "hang"? or could you elaborate more?
Jestine
Parvaiz
October 15, 2009 at 8:54 pm
hi , can i get some help, my pc starts but no display, all fans working, i checked voltage on all pins of my 20 pin smps, it was almost same as expected (checked from this - http://www.subedartech.net/docs/pc/connector_atx_pinout.GIF ) but little voltage on pin 8 (power_ok)almost .5v (no voltage mentioned in above picture) what should be the voltage if ever i need to know it, but most important is what the problem is and how i can rectify this, please help
admin
October 15, 2009 at 8:56 pm
Hi Parvaiz,
If the power_ok is only .5 volt then the power supply have problem. A low power_ok voltage could cause no display. Check all e-caps in the power supply. Sometimes a bad main filter cap could cause no power good 5 volt.
Jestine
Parvaiz
October 15, 2009 at 8:59 pm
thanks a lot for such an incredibly quick response jestine, i will soon check it out, but this comment is just to thank a wonderful person like you to respond so quickly, thank you again
admin
October 15, 2009 at 10:24 pm
No problem Parvaiz!
Jestine
Abdul Haseeb
October 21, 2009 at 3:01 am
Hi Jestine,
I did as you asked me to. Disconnected 2 HDDs and it all works fine! The external HDD got detected and working. Was definitely a problem of power shortage.
And when i had mentioned that the system does not read the extHDD actually meant that no "new hardware found" notification was displayed and the disk within the extHDD was not rotating freely as i could feel from without by the vibration. It was taking short jerks but was not working normally.
Also, do i have a solution that lets me use all 4 HDDs at once with enough power and no problems?? 😕
admin
October 21, 2009 at 8:21 pm
HI Abdul,
I guess the best is to use a bigger watt power supply as all power supply should have some extra wattage left after connected to all the loads. Otherwise the transformer may run very hot and eventually blow up the power supply.
Jestine
Parvaiz
October 23, 2009 at 3:04 pm
Hi Jestine
my atx smps was not working for last few days, yesterday when i connected mains to it, there was a little explosion, i opened the smps and found main filter capacitors somewhat out of shape with bulging/broken top, and changed both and also the blown fuse, when i connected mains again there was a hard sparking near power transistor D13007 and it was blown (broken into two)also the mains fuse blown (there are 2 more transistors in the same row, first is same D13007 other is 02N60P), what is the possible cause of this problem
Parvaiz
October 23, 2009 at 3:32 pm
moreover just forgot to mention that somebody previously had changed the switch position from 220 to 110 (possible cause of blown smps) , voltage standard here is 220, now please help me to sort out the problem
admin
October 23, 2009 at 8:49 pm
Hi Parvaiz,
Open up the power supply and check the fuse and the big filter cap.
Jestine
admin
October 23, 2009 at 8:53 pm
Hi Parvaiz,
Since you found so many components burnt, i guess you have to test out all components before turn the power supply on again.
Jestine
Parvaiz
October 23, 2009 at 8:59 pm
thanks jestine, i will try to test all components and possibly it will take lot of time, i have another atx smps, it just dosn't boot, i mean after i short fps_on and earth(common) nothing happens , no fan running etc, can u help what i should check?
admin
October 23, 2009 at 9:01 pm
Hi Parvaiz,
If there is zero volt output from the power supply then i guess you may have to start to check the fuse first and the primary side components. It could be an open resistor, shorted transistors and etc.
Jestine
fazil
November 17, 2009 at 12:59 am
i have one computer atx smps is working bu no PG (power good ) how can fix this SMPS please help
admin
November 17, 2009 at 7:19 am
HI Fazil,
No power good problem can be cause by bad filter cap in the primary or secondary side. Sometimes it can be an open resistor nearby the PWM chip in the secondary side.
Jestine
smps voltage on motherboard comport,parrel port
November 19, 2009 at 3:15 pm
please reply me
admin
November 19, 2009 at 5:25 pm
May i know what is you question?
jestine
saurav
November 24, 2009 at 1:35 pm
hello sir ,
my atx 400w smps is not working properly ,how can i solve it
admin
November 24, 2009 at 7:35 pm
Hi Saurav,
Guess you need to open up the power supply and begin to test on the components especially the primary part like fuse, bridge rectifier and e-caps.
Jestine
M.S.CHOLARAJAN
December 1, 2009 at 11:29 am
Dear all,
I am computer service engineer. But i have no knowledge in smps servicing. My SMPS is not working. That is fan is not working. Please give me solution.
jaganmohan
December 1, 2009 at 6:22 pm
Very Good Future and very nice thanking you
because i am facing that the problem in hardware thanks for said to all
Prakash
December 6, 2009 at 4:25 pm
Hi,
We want to form a Computers SMPS Manufacturing Plant near Mumbai, INDIA. We welcome any suggestion and knowlledge sharing in this regards.
Prakash
admin
December 7, 2009 at 9:33 pm
HI Prakash,
Congrat on your plan.
Jestine
admin
December 7, 2009 at 9:55 pm
Hi M.S,
Check the fuse and the primary side components. Check also the secondary filter cap too.
Jestine
rajascientist
December 24, 2009 at 7:53 am
Help full one
after connecting green and black do we really need another load like mother board.
admin
December 24, 2009 at 10:17 am
HI Raja,
Some SMPS need extra load i.e motherboard.
Jestine
ratna pratap
January 1, 2010 at 1:35 am
thank you
parvaiz
January 14, 2010 at 8:25 am
hi jestine,
my smps does not work, actually when i push power on button on my pc , fan rotates but stops automatically after 1-2 seconds, moreover if i take out 4 wire connector from smps out of mother board and keep only 20 wire connector intact, smps seems to work fine albeit pc does not boot, i have tried this smps on almost 3 or 4 motherboards, any help?
admin
January 15, 2010 at 5:28 am
Hi Parvaiz,
Have you check the e-caps in the power supply?
Jestine
axsay
January 29, 2010 at 7:18 pm
tganks
prashobh
February 3, 2010 at 10:22 pm
smps when switch on it make a sound,what the problem
prashobh
February 3, 2010 at 10:27 pm
there is no problem in output.sound is always before i switch on smps
admin
February 4, 2010 at 7:19 am
Hi prashobh,
Do you mean the power supply is working fine except that you heard the sound? Is it a high pitch sound?
Jestine
rajendra oberoi
February 22, 2010 at 10:34 am
i have a faulty smps power supply atx p4 400w i am not getting voltages on the secondary side of the smps 'xmer it seemds it is not triggering earlier one 1000mfd/16v electrolyte capacitor was busted and the round coil got bornt.I replaced the capacitor but there is noaction the round coil is ok i have checked.Pl give solution.
Regards
admin
February 23, 2010 at 6:18 am
HI Rajendra,
If the round coil burnt then it is very difficult to get back the same part. If the coil is good then i guess you may need to test all the components in the primary side. Check also for shorted components in the secondary side.
Jestine
NIDHIN DAS T.S
March 4, 2010 at 1:17 pm
pls help me,
I found that one 1/2 watt resistor and some other resistors & one power transistor is blowned ,when i replaced all and no problem with fuse my SMPS fail to give output even shorting pwr on with gnd. I chked working condition only by chking fan working, is it require any other load to be connected. How to findout any other problem with other components?.
admin
March 5, 2010 at 8:56 am
Hi Nidhin,
You need a motherboard and if possible check the secondary side diode output too. You must scan all components in the primary side.
Jestine
Srini
March 15, 2010 at 10:06 am
Hi,
My Sony computer has ATX power Supply and I get 5.34V for 5V. How do I fix this.
Thanks,
Srini
admin
March 15, 2010 at 11:34 am
Hi Shini,
Try check the filter cap or even directly change the coil.
Jestine
knaresh
March 19, 2010 at 8:44 am
i want solution about smps
admin
March 21, 2010 at 11:06 am
HI Knaresh,
Please visit http://www.PowerSupplyRepairGuide.com
Jestine
NIDHIN DAS
March 31, 2010 at 3:43 am
dear sir,
My smps is working,but it gives 3v for 5v ,5v for 12v,and the output current is too low.cooling fan was working correctly and now it is dead.but the output is same as voltage mentioned above.pls help me to troubleshoot this problem.It dosent have any atx -20pin connector ,but it have molex and mini-molex connector.wat do with "power good" wire?
admin
March 31, 2010 at 9:18 am
HI Nidhin,
I suggest that you check all the e-caps in the power supply. Check the cap in the primary and the secondary side. Power OK (power good) is a status signal generated by the power supply to notify the computer that the DC operating voltages are within the ranges required for proper computer operation (+5 VDC when power is OK)
Jestine
Kunal
April 1, 2010 at 5:27 am
my SMPS when put on for long time it gets dissconnceted automatically n when i again try to switch it on there r sparks coming out of it do i have to buy a new one or this smps could be repaired
admin
April 1, 2010 at 8:06 am
HI Kunal,
It could be dry joints in the primary power side area. If you have never repair any power supply before and do not know about the safety, i suggest that you buy a new unit.
Jestine
sujit ghosh
April 15, 2010 at 4:58 pm
i have purchase a digital multimeter and checked well condition SMPS but output power not show properly. for exsample:+12 shows +11.45.
admin
April 15, 2010 at 8:38 pm
Hi Sujit,
Have you check the filter cap? Is all the output low or just that line? If all output are low, the toroidal inductor can cause such problem.
Jestine
anil
May 11, 2010 at 5:31 am
my smps problem with sb volt 5v in but other power supply not volt
pls. solution this problem