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Forum Index : Electronics : Dead PC - help please

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domwild
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Joined: 16/12/2005
Location: Australia
Posts: 873
Posted: 10:09pm 24 Jun 2012
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Hi,

Unfortunately off topic although power supplies feature prominently as switchmode "things", which can be converted to other useful power supplies.

Inherited XP (SP3) PC, second time it happened that this PC stopped as if there was a power failure but this time it did not reboot. Fans are running and there is no video signal. What made me believe it is the power supply is that there is no LED burning on the motherboard. Hitting "DEL" does not get me into the BIOS setup screen.

1. Larger rectangular ATX plug on motherboard: Pin 3 (ground) and pin 4 give me 5.1V but I do not get 12V or 3.3V anywhere.

2. Smaller square plug shows no voltage.

There may not be any voltage as there is no load, but I can claim ignorance here. Caps look OK on motherboard, although one shows a slightly raised dome on top.

Does it mean the death of my PC or is it definitely the power supply?
Thanks.






Taxation as a means of achieving prosperity is like a man standing inside a bucket trying to lift himself up.

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Warpspeed
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Joined: 09/08/2007
Location: Australia
Posts: 4406
Posted: 12:13pm 25 Jun 2012
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Difficult to say for sure, but I would try measuring the voltages at one of the rectangular plugs.

Black will be the common ground
Red should have +5v with respect to black
Yellow should have +12v with respect to black

Those are the common voltages every PC has.

But there may also be orange, +3.3v with respect to black
Blue, -12v with respect to black

If all those are present, the power supply itself is probably fine.
Cheers,  Tony.
 
Gizmo

Admin Group

Joined: 05/06/2004
Location: Australia
Posts: 5078
Posted: 12:29pm 25 Jun 2012
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Can you borrow another power supply? Some motherboards and video cards perform a voltage test on boot, and if the voltages are not right, they stop the boot sequence, and should beep to let you know there was an error.

This page has some pin outs for the power connector, to compliment Tony's post.

Glenn
The best time to plant a tree was twenty years ago, the second best time is right now.
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domwild
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Joined: 16/12/2005
Location: Australia
Posts: 873
Posted: 01:09pm 25 Jun 2012
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Thanks for help. As I pointed out but without using colours and instead using the MSI motherboard manual with its pin-outs, I get 5.1V but no voltage on any other combination, neither 3.3 nor 12V.

Well, I will have to buy a power supply as mine are non-SATA, no worries. I believe there was a faint beep.

Thanks again.
Taxation as a means of achieving prosperity is like a man standing inside a bucket trying to lift himself up.

Winston Churchill
 
Doug

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Joined: 11/05/2010
Location: New Zealand
Posts: 41
Posted: 07:44pm 25 Jun 2012
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This may sound like a stupid question but have you checked the fuse inside the power supply?
May The Power Be With You
 
isochronic
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Joined: 21/01/2012
Location: Australia
Posts: 689
Posted: 11:52pm 25 Jun 2012
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Doesn't sound good. Some time ago I had a PC that had similar symptoms
initially, some fan movement, no led, missing power levels. The fan movement
stopped after a few (well, quite a few ) more attempts at starting. The motherboard had karked it, the power supply did not start up fully pending the
OK signal back from the board.
 
domwild
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Joined: 16/12/2005
Location: Australia
Posts: 873
Posted: 03:16pm 26 Jun 2012
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Thanks for the help. Contacting this forum is great and is much better than googling "Dead PC" and getting 20 Mio. hits!

Bought a new power supply and still no luck. Disk is OK, so it looks like the motherboard has karked it. Computers are saving us time?
Taxation as a means of achieving prosperity is like a man standing inside a bucket trying to lift himself up.

Winston Churchill
 
Warpspeed
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Joined: 09/08/2007
Location: Australia
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Posted: 03:37pm 26 Jun 2012
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Time for a new motherboard.

If the hard drive is o/k, (and it probably is) then everything can be recovered by fitting that original drive as the second hard drive to your PC.
Cheers,  Tony.
 
domwild
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Posted: 12:23pm 29 Jun 2012
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Thanks. AMD cheepo mobo $65, Athlon 2 core, Win7 $99 OEM and the surprise was the memory, 4GB of DDR3 1333 for $24! So I bought two DIMM sticks and have 8GB.

Have lost track with IT developments after teaching it for 27 years and heard to my disgust that AMD is being killed by Intel. I have always disliked the Wintel monopolies and supported Linux/AMD. Is this salesman just pushing Intel for commercial reasons?

With 4GB of memory or more one has to run the 64-bit version of Win7, which means my Sony video PMB software will not work any more so I hope the Windoze video version will do the trick. There might be more surprises in store for my old XP-based software. And I can throw out my IDE-based DVD burner/CD as the mobo does not have an IDE interface and I have to get a SATA one.

After I bought a new SATA 1TB HD I asked the salesman what I had bought, if it was a SATA or SATA2 or SATA3 disk. He said there is no such thing and chucked a wobbly, incorrect. For $100 it is most likely only SATA but the ASUS mobo manual definitely talks of SATA2 HDs. For a mere $100 I was not expecting speed but it is annoying to get incorrect info from "expirts" - ex-has been, spirt-drip under pressure.

Apparently only SSDs can be driven at SATA3 speeds.
Taxation as a means of achieving prosperity is like a man standing inside a bucket trying to lift himself up.

Winston Churchill
 
domwild
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Joined: 16/12/2005
Location: Australia
Posts: 873
Posted: 04:18pm 02 Jul 2012
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I stand corrected, again! There is most likely no SATA2 HD, which can make use of the 3Gb/sec speed of the interface.
Taxation as a means of achieving prosperity is like a man standing inside a bucket trying to lift himself up.

Winston Churchill
 
phase
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Joined: 16/09/2012
Location: Australia
Posts: 7
Posted: 12:27am 02 Oct 2012
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sata 2 drv will suffice as far as it goes.. any sata2 drv will never make the full deal of it any way..what i am saying is that the mechanics of the ."hdd" "will never be fast enough to support sata 3 ...correct...domwildEdited by phase 2012-10-03
 
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