PC Blowing Fuse and Circuit.

September 25, 2009 at 02:02:27
Specs: Windows XP

My brother turned on his PC and it sparked and blew the electrical ciruit that it was on. He then put the circuit back on and tried again but it did it again.

After this the PC Didnt come on at all.

I thought it must be his PSU so he brought the base unit to me and i fitted a new PSU. I then turned it on at my house and it blew the electrical circuit that it was on and it also blew the fuse in the power cable.

Were now at a loss to what could be causing this as it has blown the circuits at 2 different houses with 2 different PSU's and also caused the fuse (5 amp) in the power cable to go.

Anyone have any ideas on how to fix this.



See More: PC Blowing Fuse and Circuit.

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September 25, 2009 at 03:13:02
yes it is , Its done it in 2 different houses..

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September 25, 2009 at 04:41:15
Had your brother been inside the computer case prior to this happening?

Was the computer working OK prior to this happening?

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September 25, 2009 at 06:04:08
yes - its been working fine for years prior to this..

He's not technical so he wouldnt even attempt to do anything hardware wise.

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Related Solutions

September 25, 2009 at 12:49:43
State the make and model of your brand name system, or if it is a generic system, the make and model of the desktop mboard.
The specific brand name system model is usually on a label on the outside of the case somewhere, or it can be determined by going to the brand name's web site.
The model of the mboard in a generic system is usually printed in obvious larger characters on the surface of the mboard, often between the card slots.

Find the maker of the original PS on it's label and tell us what it is.

El-cheapo power supplies are a lot more likely to damage something else other than themselves when they fail like yours did. E.g. if the PS brand is BESTEC, the brand used in most emachines desktop computers and in some cheaper brand name system models, that's a lot more likely.

In any case, the switching power supplies used for computers have no large transformer for the AC voltage that is rectified into +12 volts DC. The controller chip on the board inside the PS rapidly switches the incoming AC power to provide the AC voltage that is rectified to become +12v, and relatively small sized transformers on the board transform that AC voltage to a lower voltage that is rectified to become +5v, and +3.3v.
If that controller chip goes wonky, or if components on the board fail, often it's one or more of the electrolytic capacitors that fail, the board can be briefly exposed to ten times the AC voltage that was supposed to be the voltage that is rectified into +12v before the PS fails completely, or something failing may have caused a short on the board, and in turn, the mboard or anything connected to it can be damaged because of that happening.

If your mboard is fried, that certainly could cause your problem if there is now a short on the mboard.
If there is a short on the mboard, your replacement PS is probably fried too from being connected to that mboard.

You could probably find a used mboard that is the same one on the web to replace it with, but in this case it's likely at least some of the components that were connected to the mboard when the original PS failed are damaged too.
SO - time for another system.

This was the original bad capacitor problem - has some example pictures.
History of why the exploding capacitors and which mboard makers were affected:

Defective electrolytic capacitors are still being made these days, and they're more likely to be used in el-cheapo power supplies.

Pictures of blown capacitors, other components - power supplies, Athlon cpu's, etc.:

We have noticed lately that people have been installing recent or fairly recent video cards that require your system has a PS with a greater capacity. Brand name builders are more likely to have a PS on a desktop system with a modest capacity that can't handle the video card's requirements.

Your power supply must have at least the minimum capacity required to support a system with the graphics card you are using installed, or the max graphics card you might install in the future.
(Onboard video - video built into the mboard - IS NOT A CARD!)
You can go to the video card maker's web site and look up the specs for the model - often under system requirements - the minimum PS wattage, and, more important, the minimum amperage the PS must supply at 12v is stated. If you don't find that, any card with the same video chipset including any letters after the model number has very similar minimum PS requirements.
Some power supplies have more than one +12v amperage rating - they have two - in that case you add the rated max amperages to determine the total +12v amperage rating.

A video card that requires more PS capacity than you system has often works for a while anyway, but the PS is overloaded 100% of the time and is eventually damaged and fails.

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September 25, 2009 at 14:18:28

Thanks for that, Great Detailed Response BTW and sounds like you have hit the nail on the head. First of all all the PC's we have are custom built and not brands.

The first PSU is a SUNTEK model AM608B1-300WS and the second PSU is a TAGAN model TG420-U01.

The Mboard is a MICROSTAR K7N2 (MS-6570).

The Grx Card is a Sapphire ATI Radeon 9600AT 128M DDR so not sure about its power requirements.

I was gonna get a new fuse for the power cable and start to do some Hardware elimination tests but i think i might just write this system off.

If you have anything else to add please do so.

Thx All,,

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September 25, 2009 at 15:51:26
You mean Radeon 9600XT? Regardless, power requirements are very low for the Radeon 9600 series of cards.

Without a doubt, you have a short to ground somewhere in that machine. At this point, I'd remove the motherboard from the case and benchtest with the bare minimums...motherboard cpu, 1 stick of memory, and video card. No drives need to be connected. Here's how...



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September 25, 2009 at 18:43:24
Did the fuse blow in the PSU? When you plugged it in at your house when did your circuit blow--when you plugged the cable in between the wall socket and the PC or when you turned the PC on? If the PSU has a 115/230 voltage switch, is it in the correct postion (don't guess)?

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September 25, 2009 at 22:19:02
Both Suntek and Tagan appear to be el-cheapo PS makers.

I can't find any new Suntek power supplies - just used ones.

There are a few Suntek (Power Win) listings.

I can't find any new Power Win power supplies other than that.

There are Tagan listings for your model - e.g.11.49 pounds =
$19.99 Canadian dollars.

"If the PSU has a 115/230 voltage switch, is it in the correct postion (don't guess)?"

Most PSs have a recessed slide switch on the back of the PS that you can see at the back of the computer case when the PSisinstalled in the case - it's usually red with white lettering - it has to be all the way to one side or the other and show the voltage your AC is where you are using the computer. It's extremely unlikely that switch is in the wrong position. It normally can't get accidently moved. It's normally only a problem when someone has moved from one country to another, the standard AC voltages are different, and they forgot to move the slide switch to the proper position.

You problem was probably caused by a defective electrolytic capicitor failng in your Suntek el-cheapo power supply.

I suspect your shorted mboard has fried the Tagan PS.

I would not connect your mboard or either PS to anything you don't want to fry.

"MICROSTAR K7N2 (MS-6570)"

There were a lot of MSI mboards of that era that were affected by the defective capacitor problem, but chances are if it had that problem it would have failed years ago, unless it's been sitting un-used a long time.

You could try the cpu, and ram, in a working mboard, and the drives on another computer, but it sounds like you have probably got catastrophic damage, and I wouldn't be surprised if most of if not all of those are damaged too, and they may harm another computer / mboard.

Don't buy an el-cheapo PS.
See response 3 in this:

You should be paying at least twice what you probably paid for that Tagan PS for a decent PS.

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