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PC wont power up after power failure

October 13, 2011 at 07:05:28
Specs: Windows XP

computer will not power up /had power fail in my home while I was online

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#1
October 13, 2011 at 08:42:22

Tell us the make and model of your brand name system, or if you have a generic desktop system, the make and model of the mboard.

The specific model of a brand name system is often shown on a label on the outside of the case somewhere, or it can often be determined by going to the brand name's web site and loading a program they have available, if Windows is still working, on the subject computer.

If it's a Dell computer...
Go here for how to find the Service tag "number":
http://support.dell.com/support/top...

Tell us what it is.

If it's a HP or Compaq computer.....
Go here:
http://partsurfer.hp.com/search.aspx
Scroll down a bit.
Look for the similar label on the outside of your computer.
Quote the specific model number - that's at the end of the first line.
Quote the Product number - that's on the third line.

The model, sometimes the make, of a mboard in a generic desktop system is usually printed on the mboard's surface in obvious larger characters, often between the slots.
..........

Is your computer a laptop or netbook, or a desktop computer ?

Power failure events often produce power spikes or surges that can damage computers or anything connected to them. If the power failure event was caused by a lightning strike, then it's even more likely your computer could have been damaged.

Anything on the computer or connected to it could have been damaged.

If this computer is a laptop or netbook, then it's likely you can't do anything about the problem - probably something must be replaced if you want to continue to use the computer Take it to a local repair place and have them analyze what's wrong and how much it would cost to fix it. .


If this computer is a desktop computer, if you are fortunate, it's frequently the situation that only the computer's power supply was damaged. If you can, remove the AC power to the case, try connecting a power supply from a working computer (from another computer you have or a friend's ) to your rmboard to see if it will then boot normally (it should have at least the same max (output) power rating on it's label as your PS) .
Sometimes a power failure event makes some connections poor Another thing you can try is to remove the AC power to the case, open up the case and unplug and them plug back in every connection and your ram any cards you have in mboard slots, then connect the AC power and try the computer.
If nothing you try gets your computer working, take it to a local repair place and have them analyze what's wrong and how much it would cost to fix it. .


If you have personal data on the hard drive you can't replace that you don't want to lose, usually the hard drive was not damaged. It can be removed and connected to another computer so that you can copy the data you want to elsewhere if you wish to do so.


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#2
October 13, 2011 at 09:11:00

I bought it from neighbor, home build computer, did not have Ethernet or hard drive it's Pentium 4 processor,4.0 gig.160 HD.Board/Intel D875PBZ has 5 fans 2 front, 1 top, 2 rear.Video,2 DVD CD, small floppy,

O.S. Windows XP
was working fine until power in my home went off while I was on Facebook in middle of a game.Power is plugged into P/Jack power protector..Monitor 17" flat screen is plugged into same it works.


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#3
October 13, 2011 at 13:18:35

"Power is plugged into P/Jack power protector..Monitor 17" flat screen is plugged into same it works."

Some protection devices have an led that indicates the protection is still working, supposedly. If yours has that, is it still lit up ? If it isn't you must replace the device - try plugging drectly into AC power.

If the power failure event was caused by a lightning strike, the effects caused by that can pass through any protective device you are using It's even possible for computers that have their AC power source switched off to be damaged, if the computer is still plugged in - very high voltage spikes can be produced that can jump the contacts of any switch that is switched off. (The protected led may be still be on, yet damage was done.)

If you DO use (a) device(s) that protect(s) your computer from damage caused by power spikes and surges
- you computer's AC power source and EVERYTHING that connects to your computer must be pluggeed into such a device, otherwise you're not really protected.- everything that connects to your computer that plugs into AC power directly or via an AC to DC adapter, AND the cable that connects you to the internet (coax cable or telephone cable) if you're connected to a modem or a router or a combo router/modem via a network cable, and the telephone cable if you're using a dial-up modem connection to your computer or to a connected multi-function device or fax machine. It's recommended that if you need to use somerthing to protect a telelphone cable connection that you use a separate protection device for that - many protection devices will dump a voltage surge or spike from an AC source through the telephone cable port otherwise.
UPS devices usually do not have enough places to plug in everything connected to the computer.

Note that in most cases, all the protection devices have to be the same brand, otherwise the warranty against damage is not valid.

Try the suggestions for desktop computers in response 1.
If you are fortunate, it may be only the PS that has been damaged, or unplugging and plugging back in stuff may work.

Damaged power supplies often partially work - leds may come on, on the computer, fans and hard drives may spin, yet the PS will not fully work and you get no video and no mboard beeps. They have an integrated chip on them that determines when it gets turened fully on and that's easily damaged. The fuse inside the power supply usually does not blow in any case.

(The following does not apply to power supplies or assembled computers or computer cases with power supplies bought in North America.)
NOTE that if you're in the UK or some other place (Europe ?) that has the requirement, the power cord to the PS may have a tiny fuse in t's plug that may have blown - check that - there's a tiny access cover in the plug in that case that you need to remove or slide so you can examine the fuse. .

There is usually an led on the surface of the mboard that lights up when the power supply has live AC power to it, whether the computer is running or not.
If that doesn't light up, either your power supply is fried (most likely) or the mboard is severely damaged

Note that certain brands of PSs are well known to be a lot more likely to damage something else when they fail.
What brand is yours ?
E.g. BESTEC power supplies are used in most emachines desktop computers and some cheaper models of other brand names, and are available for use in generic systems. They have a reputation for frying something else while failing or when they fail completely - often the mboard, sometimes other things too.

Better quality power supplies have superior features that shut off the PS automatically under several different conditions, and are more likely to do that BEFORE they have been damaged. In that case, you may need to unplug the power supply or switch off the AC power to it for at least 5 minutes, then it will reset itself and work fine again.
E.g. I've needed to do that with Enermax PSs.


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Related Solutions

#4
October 14, 2011 at 00:06:57

I'm a hvac man by trade, check voltage to machine with meter 120VDC into back nothing coming out of power supply.

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#5
October 14, 2011 at 00:07:57

Thank you for your help.

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#6
October 14, 2011 at 08:07:18

> check voltage to machine with meter 120VDC into back nothing coming out of power supply.

Ideal voltage for all computers is even when incandescent bulbs dim to 40% intensity. The meter must be used where it can report on all components of that computer's power supply 'system'.

Set the multimeter to 20 VDC. Connect its black probe to the chassis. Touch the red probe to a purple wire where the PSU connects to the motherboard. Meter should read about 5 volts. But report all three digits. Repeat same for a green and gray wire. Report numbers before and as the power button is pressed. And finally monitor any one red, orange, and yellow wire as the power switch is pressed. Note any rise and final voltage number on each.

Post those three digit numbers. Relevant components will be accused or exonerated in a next reply without speculation based on those hard numbers.


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#7
October 15, 2011 at 08:14:07

The only sure way of ruling out the power supply as the cause of your problem is to try another one.

If you can, try connecting a known good power supply that has at least the same (max output) wattage capacity as on the power supply's label.

"(The following does not apply to power supplies or assembled computers or computer cases with power supplies bought in North America.)
NOTE that if you're in the UK or some other place (Europe ?) that has the requirement, the power cord to the PS may have a tiny fuse in t's plug that may have blown - check that - there's a tiny access cover in the plug in that case that you need to remove or slide so you can examine the fuse. .

There is usually an led on the surface of the mboard that lights up when the power supply has live AC power to it, whether the computer is running or not.
If that doesn't light up, either your power supply is fried (most likely) or the mboard is severely damaged"


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#8
October 20, 2011 at 10:10:59

Removed power supply , found burn't capacitor and transistors.I will replace it when I have the money. Thanks for your help.

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#9
October 20, 2011 at 13:29:34

Okay - hopefully that all that's wrong.

You didn't tell us the make and model of your computer. Some desktop systems have el-cheapo power supplies that are well known to be a lot more likely to damage something else while failing. E.g if the power supply brand is BESTEC, it's a lot more likely it damaged the mboard.
Emachines desktop computers, and some cheaper models of other brand name computers, come with BESTEC power supplies.


You can usually replace it with any decent quality standard sized standard ATX PS with the same capacity or greater.

Standard (PS/2) power supply size - 86mm high, 150mm wide, 140mm deep, or 3 3/8" h x 5 7/8" w x 5 1/2" d , or very close to that, though the depth can be more or less for some PSs.

Don't buy an el-cheapo (in quality) PS.
See response 3 in this:
http://www.computing.net/answers/ha...

Note - I may have mentioned Coolermaster in that - I have recently found some models have only a 1 year warranty, some are known to have premature fan failures, some are known to develop failing electrolytic capacitors.
.....

If you have a video card installed in a mboard slot...

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 ! )
If that info is not in the ad for the video 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 two or more +12v ratings - in that case, add those ratings to determine the total +12v current capacity.

If you're a gamer...
In most if not all cases, the max capacity rating of the PS is an intermittent rating. It's recommended that you do not load your PS to any more that 80% of that rating if you are going to be using something that puts a constant load on it, such as playing a recent game for hours on end. In that case, you multiply the min capacity stated for the system with the particular video chipset on the card by 1.25 to find the min. capacity of the PS you should get.



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