Need some inputs regarding a shortcircuited motherboard

Discussion in 'General Electronics Chat' started by whitestar999, Nov 20, 2014.

  1. whitestar999

    Thread Starter New Member

    Nov 20, 2014
    I was doing some searching for possible reasons of a short circuited mobo & came across this forum & found it to be quite informative.I had an intel H61 mobo which was working correctly until a few days ago when i shut down the pc due to power cut & then tried turning it on after 20 min when power came back.After a few unsuccessful attempts i noticed that case fan & cpu fan just starts spinning & stops after a second of turning on the power button.Thinking of short circuiting i took out the mobo & place it on a newspaper with only cpu/HSF & ram(later i removed ram also),tried turning it on by shorting the power pins on mobo with the same result.I took it out to a shopkeeper to rule out any psu issue & he too said mobo issue.

    Now this is where it gets interesting.After bringing back the mobo home i cleaned it once again(blowing air from mouth to some places & dried hands),took off the CMOS battery for 1-2 min & put it back again.Now again assembled connected the mobo+cpu/hsf to psu & shorted the power pins(like i did many times earlier) but this time there was a spark instantaneously followed by a short flame on a small section of mobo beside cpu.I immediately turned off the psu.I once again turned it on & spark followed by a short flame appeared ar same place.

    Now i know mobo is gone & certainly not covered by warranty with clearly physical damage.What i want to know is the possible reason.I took it to another shop to confirm if any other component might have been gone too but found out that cpu as well as ram are OK.My theory is that that particular section of mobo where flame/spark appeared was being shotcircuited initially but my repeated attempts of turning it on caused it to behave just like a closed circuit resulting in the spark/flame but i am not convinced.PSU may also be the culprit but then how did it manage to cause such damage only after so many attempts when it was working correctly for months.I thought about checking psu with multimeter but from whatever i read it seems the usual cheap digital multimeter is not very accurate considering we are talking about checking 12v,5v & 3.3v.e.g.say multimeter shows me values as 12.1,5.1 & 3.2 is it enough to cause this damage.I am getting a new mobo for sure but if psu is the culprit then my budget calculations will be completely off hence i want to make sure if it is worth the extra money & time(i will need to save for extra money).This system was connected to an UPS & being an intel pentium G620+ati 7770 system+2 hdd total power draw is not even 150w at startup i believe.PSU is almost 3 years old FSP Saga II which is quite decent as per many reviews & certainly more than enough for this system.

    If it helps this is my 2nd intel mobo gone in last 1 year,earlier one was an intel atom system which just didn't turned on(not even a short circuit symptom) after a successful shutdown but it used to be on for days without break & was 2 years old.This H61 mobo was used for ~8 months with moderate usage in last 2 months.
  2. wayneh


    Sep 9, 2010
    Absolutely not. Those values are completely reasonable. I would be leary, though of measuring the PSU voltages without a load attached. Those voltages appear to be in regulation, but some PSUs require a few watts of load (such as a small automotive lightbulb) to achieve regulation.

    I'm not saying your PSU is completely off the hook, just that your measurements are well in line.
  3. ISB123

    Well-Known Member

    May 21, 2014
    Maybe you connected something the other way around?
  4. whitestar999

    Thread Starter New Member

    Nov 20, 2014
    I am sure i didn't connected anything the wrong way & even if i wanted how could i do it.all i did was connect 24 pin psu cable to mobo which you can not connect in a wrong way(holes won't match not to mention i have done it a few dozen times).

    I also thought of attaching a load but the thing is what to attach which i can get from nearby shop(e.g.just saying automotive bulb will leave almost all usual shopkeepers here confused not to mention it also costs almost 1/4th of a new mobo cost.hdd is out of question as i consider data more important than hardware itself.mobo is already out of question because of short/closed circuit section.i am not sure if a 120mm case fan will do the job.i am thinking of biting the bullet on this one by getting a cheap gigabyte or asus h61 mobo.