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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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rajeev nanda
August 25, 2008 at 3:51 pm
-5v drop in ATX SMPS . How can repair it
admin
August 25, 2008 at 8:14 pm
Hi Rajeev,
Try tracing the -5 volt line perhaps it could have a filter cap along the input that have high ESR value and need replacement.
Jestine
shiju
September 17, 2008 at 9:56 am
i have a SMPS with 12 pins 6*2 how can i test that
admin
September 17, 2008 at 8:15 pm
Hi Shiju,
What sort of SMPS is that? The SMPS connected to what type of board? I need more info in order to help you out.
Jestine
Ruben
November 2, 2008 at 6:54 pm
Good day sir Jestine just want to ask. I have atx psu got repaired by myself. The power is all ok but when i check the voltage out put it turns out that the output is like breathing or fluctuating. the 12v is like 11v to 12v, 5v 4v, 3.3 3v... ..Would you give e some tips if it is on the primary or secondary section...By the way i change all the filter capacitors in the primary and secondary section thanks in advance and more power...
admin
November 3, 2008 at 10:24 pm
Hi Ruben,
Did you plug in a load like a motherboard? Power cycling cause can be in the primary and secondary but the percentage is higher in the secondary side. If this power supply do use an optoisolator, make sure you check this circuit components. I do came across a bad inductor (the round coil) also can cause the power to cycle. Hope this helps!
Best regards,
Jestine Yong
Ruben
November 3, 2008 at 11:07 pm
Thanks for the quick reply sir Jestine. Yes sir i plug a load into it. I'll double check the secondary section thanks again sir for the time and i'll update you if it works.. I got 3 pcs. of this kind of generic atx and its all have the same problem. It came to my shop with a bad auxilary fan. and no power. I just change all the filter capacitor that bloated in the secondary section and change the auxilary fan. And got a power But
the output is not stable and i hear a ticking sound when the voltage drop to 11v to 12v (like a whining sound tic tic tic tic tic). The ticking sounds like a shorted diode but i change all the diode also thanks again sir... And have a nice day....
srinivas
November 13, 2008 at 3:14 pm
My computer used 250w Atx power supply but out voltages 12v,5v,3.3v,nothing is coming,how to rectifing problem.pls tell me.
admin
November 14, 2008 at 11:50 pm
Hi Srinivas,
Have you check the fuse, switching transistor, secondary output diode, filetr cap and etc ?
Jestine
S.R.V.V.NARASIMHA RAO
December 21, 2008 at 1:48 am
I want to know how is working atx smps, PLEASE GIVE ME ONE CIRCUIT AND THEORY
admin
December 24, 2008 at 6:28 pm
Try visit this website:
http://www.kellerstudio.de/repairfaq/sam/smpsfaq.htm
Jestine
srinivas
January 8, 2009 at 7:32 pm
My computer used 250w Atx power supply but out voltages 12v,5v,3.3v,is coming,but any load used to nothing is coming,load used to just tripping and no voltage coming,how to rectifing problem.pls tell me.
admin
January 8, 2009 at 10:19 pm
Hi Srinivas,
Try check the filter capacitor as any bad filter capacitors in the output section could cause power supply to breakdown when under load.
Jestine
Bawa computer
January 18, 2009 at 8:53 pm
how to troubleshoot of complete smps
admin
January 18, 2009 at 11:40 pm
Hi Bawa,
Check this link out:
http://repairfaq.cis.upenn.edu/sam/smpsfaq.htm
Jestine
gauri
April 1, 2009 at 12:59 am
very good
thanks for smps test tips
sebastin lawrence
July 1, 2009 at 2:47 pm
Thanks
sujit
July 10, 2009 at 2:40 am
i useful this information but i want to know i this above picture which pin u used for sofring that motherboard. can u plse guide me. which pin i used for sorting motherboard.
and in case of if i am using only axe motherboard then which wire need to short.
admin
July 10, 2009 at 8:34 pm
Hi Sujit,
Short the two wires as seen from the photo.
Jestine
sujit
July 21, 2009 at 3:41 am
hello sir
my first step if i don't have any scrap motherboard then i remove all connection of smps from mother board. then i need to put that pin but which two pin req? can u please explain me. i know above picture i need to put that pin in to green and black sockt but which pin require? u got my point example safty pin, or which pin can i get this pin in computer store,and my third step i start switch my i correct if not then please give me correct reply.
my secound question
how much volate get to cpu, ram, lanport, hard disk through power supply.
My third question,
how i know how to identityfy power and rester button if not clearly mention in motherboard, where we connect cabinet wire rester and power supply.
please help me Sir.
sujit
sujitmayekar@rediffmail.com.
please reply.
Vijay
July 26, 2009 at 10:39 pm
Hi Jestine,
Thanks for posting this. Just one doubt.
First of all i dont have a electronics background.. I shorted those two pins. Connected a 4 pin plug from SMPS to a fan(I have an extra detachable fan).
Now by giving power supply to SMPS, should the fan work if my SMPS is good?
Thanks,
vijay.
khader basha
July 27, 2009 at 4:16 pm
how to repair s.m.p.s
admin
July 27, 2009 at 9:17 pm
Hi Vijay,
It depends as some power supply need fully load to work properly otherwise the internal fan may turn for a while and then stop. Try put more load like hard disk, motherboard and etc.
Jestine
admin
July 27, 2009 at 9:19 pm
HI Khader,
Please visit this link;
http://www.repairfaq.org/sam/smpsfaq.htm
Jestine
admin
July 29, 2009 at 8:32 pm
HI Sujit,
Try this link:
http://www.smpspowersupply.com/connectors-pinouts.html
Jestine
Kinku
August 15, 2009 at 7:15 pm
Hi Jestin,
The power button of my PC is not turning on the PC. After testing I found that the Motherboard is not turning the SMPS on. It works fine if I short the PWR_ON with ground with a wire and then press the Power on button. Can you please suggest what could be the problem?
Thanks and regards,
Kinku
admin
August 16, 2009 at 10:55 pm
Hi Kinku,
From your description it seems that the problem is in the motherboard but sorry i have never come across such problem in motherboard thus i could not give any expertise advice on this matter.
Jestine
aspak
August 18, 2009 at 8:22 pm
what is the full form of smps.
admin
August 19, 2009 at 7:23 pm
Hi Aspak,
SMPS means Switch Mode Power Supplies.
Jestine
AKASH MISTRY
August 24, 2009 at 12:51 pm
Sir, I am searching for an equipment which can test or measure the parameters like VOLTAGE and CURRENT coming out from the SMPS of COMPUTER. I am final year student of ELECTRONIOCS AND COMMUNICATION ENGINEERING and going to deplope an equipment which can measure all test points of SMPS.
admin
August 24, 2009 at 8:12 pm
Hi Akash,
That's good and keep up the good work!
Jestine
Neel Chauhan
August 24, 2009 at 11:00 pm
I did this on a old PSU and it did not care about the scrap motherboard and the hard drive. I just used a cable from the green to the black and I did it. My PSU is not that. It supports 220V but it also supports 110V in my area.
admin
August 25, 2009 at 5:02 pm
HI Neel,
May i know what is your question?
Jestine
AKASH MISTRY
August 27, 2009 at 12:03 pm
Thank You sir...but please provide me some information regarding SMPS TESTING and CALIBRATING EQUIPMENT in details.....please mail me as early as possible...
ramesh
August 31, 2009 at 9:35 pm
it right sir
what can i do when ps volt 2.5
admin
August 31, 2009 at 9:39 pm
Hi Akash,
Sorry i do not have the calibration of equipment info. For the SMPS testing i guess you can read from this blog post to test the SMPS.
Jestine
admin
August 31, 2009 at 9:43 pm
HI Ramesh,
Could you elaborate and provide more info?
Jestine
neeraj belwal
September 3, 2009 at 7:19 pm
My atx smps is creating some problems sometimes it is working fine but in most of the cases the power from smps suddenly gets off when pc is running and when i removed all the connectors and main cord of smps it started working and than after some time the same fault it gave what can be the problem and how can i resiolve it.
admin
September 3, 2009 at 11:56 pm
HI Neeraj,
Try check the filter capacitor first at the output of the smps.
Jestine
suresh
September 10, 2009 at 2:19 pm
how should i test a smps mother board and what test should be done on it to know its performance
admin
September 11, 2009 at 9:34 pm
Hi Suresh,
Connect the smps to a load and power on. Test all the output voltages with your meter.
Jestine
Atul Kumar Kuthiala
September 20, 2009 at 11:30 pm
Thank you very much for your tip about testing of ATX SMPS. Can you please tell how critical is +12V supply if measured as 11.75V (partial load) and full load 11.48V with a digital VM, for running on-board VGA graphics on INTEL DG965 MB. The SMPS runs all fans, HDDs etc. but no video output. Monitor and cable fine. SMPS and system have been running fine for almost 3 years. It is 20+4, 400 W.
Thank you.
admin
September 23, 2009 at 10:12 pm
HI Atul,
Have you replace with another good SMPS to make sure is the power supply fault. As for the 12 volt, most motherboard need at least 12 volt to run. I guess you have to confirm first whether is the SMPS or the motherboard fault.
Jestine
thanhdonhat
September 24, 2009 at 5:14 pm
i want study repair about latop.thanks
thanhdonhat
September 24, 2009 at 5:16 pm
my PSU into mainboard do not run
admin
September 24, 2009 at 8:30 pm
HI Thant,
Sorry no laptop repair course.
Jestine
admin
September 24, 2009 at 8:31 pm
Hi Thant,
I guess you need to open up the power supply and begin to check on the components like fuse, bridge rectifier, power semiconductors and etc.
Jestine
skani
October 5, 2009 at 5:35 pm
Hello Sir am H/W engg i want to learn smps circuits so pls send me details thanking you
admin
October 5, 2009 at 8:03 pm
HI Skani,
Try this link;
http://www.repairfaq.org/sam/smpsfaq.htm
Jestine
Abdul Haseeb
October 10, 2009 at 9:24 pm
Hi Jestine,
I've got a Intel D945GCL working fine. I have a Toshiba external HDD 250GB which was working fine until some time ago. My system doesn't read it at all now. It works on all other systems and laptops. I figure out from my knowledge that the problem is power shortage as i have 3 internal HDD's, a DVD Writer and a fan connected to the SMPS.
Could that be the cause of the prob?
And also, the 20-wire cable from the SMPS(as shown in picure above) is connected to a 24-pin socket on the motherboard. A separate 4-wire cable is left disconnected which would fit in the remaining 4 pins. Why is this disconnected? Does it provide additional power to the motherboard??
Please help. Thanks.