[Solved] Bang and spark at the end of the kettle plug type lead

[mij]

Yes it is the new one which I'd fitted in the casing - wasn't I optimistic :). I am not going to couple up the old one again, I don't like sparks and bangs.

 

Ok another on order, send this one back! Oh dear me, what a palaver!

Jim.

[KenB]

When you get the new one check it out before you put it in the case.

Just plug it in to see if the fan rotates and check that the 12v supply is working.

 

I hope that there isn't a problem within the case causing the PSU problems.

[mij]

Thank you for your response KenB. It is good to know that someone is there :).

 

You said "I hope that there isn't a problem within the case causing the PSU problems"

 

I also hope all is well within the computer case as well, it might also cause another PSU to give its final volts.

It might mean that I'll have to get a new desktop after all. I am unsure if I can get another with W7 in it though. Mind you I could always rebuild this desktop here :).

Jim.

[Rustys]

The shorting out [ initial post ] could have taken out your motherboard.

Not just the motherboard what about the other hardware on the system?

RAM

HDD

Video

[KenB]

I am unsure if I can get another with W7 in it though.

I doubt you would find a new machine with Win7 - you may have to look for second hand / re-furbished machine

or a version of Win7 CD that has not been used.

 

The fans are not turning and nothing is lighting up

This would seem to indicate a PSU / motherboard problem NOT a RAM / Hard-drive or VideoCard problem.

This hardware could well have been damaged too BUT the symptoms explained indicate a PSU or Motherboard

 

Let's see what happens with a replacement PSU :)

Edited September 10, 2018 by KenB

[mij]

The new PSU arrived today. I have plugged it into the mains and the fan does not turn at all.

Not very inspiring! Shouldn't it at least run the fan?

Jim.

PS I have checked the lead (new fuse) it is ok. Used another lead just to make sure and still not turning the fan.

Edited September 11, 2018 by mij

[Rustys]

The new PSU arrived today. I have plugged it into the mains and the fan does not turn at all.

Not very inspiring! Shouldn't it at least run the fan?

Jim.

PS I have checked the lead (new fuse) it is ok. Used another lead just to make sure and still not turning the fan.

No it will not run unless a complete circuit is created. So it has to be plugged in to the Motherboard to complete the circuit.

[mij]

Thanks for the input Rustys. Ok i'll try that in the morning.

Jim

[mij]

It is a few days later, I am also a male nurse BTW - unqualified at that :).

 

I have now plugged in the new PSU and the 24 pin thingy (see photo, the plug is between my fingers) and nothing turns or lights up.

I'm assuming that the mobo is powered by the 24pin plug. Since both PSUs do not work with the 24pin plug connected does this mean the mobo is suspect? I hardly think that 2 PSUs are defective.

Jim.

[mij]

I have now tried both PSUs and there is nothing coming out of either. I have double checked the lead/fuse in the mains lead with another electrical item and that proves it is OK. I have also connected both up to the 24 pinned mobo connection and still nothing. I could use Victor Meldrews words here but it's beyond the pale.

Jim

Edited September 16, 2018 by mij

[KenB]

Hi Jim,

 

Unplug the lead to the PSU from the wall.

 

Take off the motherboard the 24 pin connection.

 

Locate pins 15 and 16 [ black and green ] and use a metal paper clip or piece of wire to short them out.

[ Connect them together ]

This fools the PSU into thinking that it is connected to the Motherboard.

 

Plug in at the wall again.

 

Check the voltages now.

[mij]

Hooray! Getting something. The fan turns on the first new one (saves sending it back) and getting the 12.something volts on the yellow wires :).

 

The same happened on the second new one too :).

 

Ok, ready to move on tomorrow and feeling a bit better about it now.

 

Thanks for that KenB.

Jim.

Edited September 16, 2018 by mij

[KenB]

Hi Jim,

 

Check the voltages on the 12v - 5v - 3.3v wires. [ There are negative voltages on a couple ]

Check that the "Ground" wires are not reading any voltage.

The recorded voltages should be pretty close to the diagram.

Make a note of the pin number and the voltage recorded.

 

If the PSU checks out OK - unplug from the mains - and remove the shorting link.

 

Take the RAM out of the Motherboard and remove the Video Card too - if you have one.

Remove any other cards that you may have [ Sound ? - Network ? - etc ]

DO NOT remove fans - just hardware that is plugged in to the Motherboard.

 

Also remove any leads connected to the Motherboard from the Hard Drive / DVD etc.

Make a note of where they were removed from.

Disconnect any external devices - monitor / printer etc.

 

Still with the PSU unplugged .....

 

Check the Motherboard for burn marks or blown capacitors.

 

 

If there are no obvious problems [ burn marks / capacitors ] then ......

 

Assemble the PSU into the computer casing [ don't connect any of the cables yet ]

Connect ONLY the 24-way socket to the motherboard.

 

Be VERY careful here as you said that you got sparks etc .......

Switch on at the wall.

 

The PSU fan should spin and the Case Fan / CPU Fan should spin.

Edited September 17, 2018 by KenB

[mij]

I have done that and all was correct except pin 20 that had no connecter in it - this was also true of the old PSU taken out.

 

The results are as shown in the photo. I had to use a work around for that as the FUJI camera did not show in the scan photo box. Only the printer scanner. It worked ok before. I hope I can add it and you can enlarge it.

Jim.

 

[KenB]

Hi Jim - those voltages look OK.

 

The -5v [ no connection ] is nothing to worry about.

Some of the very old motherboards used it - but not modern ones.

 

I have added to my previous post for what to do next.

[mij]

5 minutes ago

#41

 

 

 

Thanksfor that KenB, I have had a look at the mobo but nothing is obvious from this side. I will look again tomorrow morning with daylight as my eyes are not what they used to be.

 

I took a look at the old PSU that went out with a bang and a big spark. A capaciter seems to have blown its glass end off and at the end of a white lead there is a large blob of something. Peering through the mesh of one of the good PSUs the white lead should have a white plug at the end. Perhaps this has melted during the bang/spark! It seems it may have taken out other electronics that it was connected to. Oh dear, I feel a rebuild coming on :censored:. I have attached a photo of the old PSU, the white blob (melted white plug) is at the end of the white lead and just up from the green rectangular board. The flash has made the photo difficult to see and if that is so I can do another tomorrow in daylight.

Jim.

Edited September 17, 2018 by mij

[mij]

I have just tried that thumbnail and it didn't enlarge on this loopy laptop. It works one day then nothing the next. I'll try again tomorrow.

Oh for my W7 machine.....

Jim.

[mij]

My 2nd photo of the burnt out PSU is attached hopefully. Without the flash it is a little more obvious of the damage to the PSU. It shows the melted white plug but the blown 'glass' capaciter is end on and not so visible. It is next to the melted white plug and just above it.

Jim.

PS It wasn't until I magnified the image that I saw the largish capaciter had melted black something (used to be pitch) and closer inspection showed what I thought was a glass capacitor was looking more like a fuse that had blown apart. I think you may have known that.

 

 

Edited September 18, 2018 by mij

[mij]

I have done the next check and with the 1st new PSU connected to the mother board, there is no turning of the fans in the PSU or the fan on the mobo itself :(.

 

I assume this means the mobo and/or the chip is defunct :( ?

Jim

Edited September 18, 2018 by mij

[KenB]

Hi Jim,

Can you post some close-up pics of your motherboard please ?

 

Before I suggest that it is dead there is something I would like to check.

Edited September 18, 2018 by KenB

[mij]

I have tried to get close but the photo goes out of focus. I can always try again if these are unsatisfactory.

Jim.

 

 

 

[KenB]

Hi

Thanks for the photos - they are a bit blurred - but I did manage to locate the Model Number.

Gigabyte GA-78LMT-USB3

 

The manual can be found here - http://download.gigabyte.asia/FileList/Manual/mb_manual_ga-78lmt-usb3_v.5.0_e.pdf

 

There is an ATX 12v connection on this board. [ see image ]

 

Try the following: Assuming that you left the M-Board in the case ?

1. Unplug from the wall.

2. Connect the 24 way connection.

3. Connect the ATX 12v connection.

4. Put in 1 RAM module

 

Now be VERY careful again ....

5. Plug in the PSU to the wall socket and switch on

6. Press the On / Off button on the case. [ Keep your eyes away from the PSU / M-Board ....just in case ]

 

Is there any life showing now ?

Edited September 18, 2018 by KenB

[Rustys]

If that link to the manual does not work for you try

 

Gigabyte GA-78LMT-USB3 Manuals

[mij]

Before I carry out this move one of the leads left over was the ATX lead which should have 12V on each yellow lead. But there is only four connecters on it. I have leads here which adapt 4 connecter plugs to the 8 connecter plug on the mobo. They simply take two yellow and make them four yellow which are connected to all one side of the ATX connecter. Similarly with the two black leads from the other side of the PSU plug. Two black leads into the four connecters on the motherboard. That might sound like gobbdy gook, perhaps a photo will help. Maybe I should use these as it will supply life to the whole plug.

Jim.

 

Edited September 18, 2018 by mij

[KenB]

Hi Jim,

 

Maybe I should use these as it will supply life to the whole plug.

???

They simply take two yellow and make them four yellow ....

If your PSU doesn't have an 8 pin ATX 12v connector you will need to use one of the 4 pin to 8 pin leads as you suggest.

[ unless the PSU has 2x 4 pin connectors that would do the job ? ]

Edited September 18, 2018 by KenB