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Desktop PC Died


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#1 lolwat

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Posted 28 November 2008 - 07:04 PM

So I have this custom built desktop PC my dad's friend built for me. Recently while I was playing a game on it (World of Warcraft) it suddenly turns off and I could smell that burnt electrical type smell. Then I waited like a little while and tried turning it on and it came on for a split second and turned off. Now it won't come on at all. It has lights on the front and side of it and what I thought was weird was just when I plug the PC cord into the back of it 3 fans come on for a split second and so do the lights but like I said it won't power up when I press the power button. When I unplug the power cord from it, the front power button blinks like 3 seconds after it's unplugged.

If you need anymore information just ask.

Any ideas or thoughts on what might be the problem and how can I check to see if it is actually the problem without having to buy a new part just to test it.

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#2 Sterling14

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Posted 28 November 2008 - 08:16 PM

Welcome to bleepingcomputer!

That burnt smell is never a good sign. I'd hate to say it, but something may have died. I'd think it's either:
1. Power supply
2. Ram
3. Motherboard

The best thing you can try is take the cmos battery out for a few minutes. Open up your computer case (unplug it first of course, and touch something metal to ground yourself from static). On the motherboard, you should see a watch battery, about the size of a quarter, somewhere on the motherboard. Take it out for a few minutes, then put it back in. Put the computer back together and see if that helped any.

Besides this, I can't really think of anything else, except swapping out parts with another system. The easiest thing to do is if you have multiple sticks of ram, try one at a time, and try each one in different slots. You can also try different sticks of ram, that you know work and are compatible with the system. From there, I would try a different power supply in your system. From there on, I don't think anything would really smoke up like that except maybe the motherboard.
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#3 dpunisher

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Posted 28 November 2008 - 08:41 PM

I go for simplicity in diagnosis......... the smell test. Sniff the back of the power supply, and you should get that refreshing "I just let the smoke out of the wires" aroma. It will be evident. Also a good idea to have a quick look around the motherboard for anything obvious like a blown capacitor or other toasty component. Do not power it up if you don't have to. You take a chance on more damage everytime the power supply cycles on. If you are lucky the power supply died and didn't kill anything else.

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#4 lolwat

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Posted 28 November 2008 - 09:11 PM

Thanks for the welcome and thanks for the replies guys. :thumbsup:

I tried removing the cmos battery for a few minutes and putting it back in and that didn't work.

I tried moving my 2 sticks of ram in different slots one at a time and still had no luck. If one of them went bad would that mean more than likely both of them messed up?

I don't believe I could get a power supply to test in it for awhile, but when I try to sniff for that burnt smell from the back of my PC where it's at I don't smell anything. If I sniff with the side cover off near it I can smell the burnt smell a tiny bit. My PC has been messed up for a little over a day now so that could play a roll in that maybe.

#5 Dennis the Menace

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Posted 29 November 2008 - 11:36 AM

lowat
Sorry to hear about your loss. I've read thru the other replies and can offer a couple more alternative tests.

First, do you have and know how to use a multimeter? If so you can check the voltages where the power supply plugs into the mother-board. If no about the multimeter then I would unplug the large white connector from the power supply to the mother-board. Then power up the system for a few seconds. If the fan starts in the power supply and as you said the smell is not prime by the power supply we can presume that the power-supply is okay.

Next, as "dpunisher" stated - the smell is the clue. Look around very closely near where each of the connectors from the power supply connect to the mother-board for an IC which looks burned. Be sure you look very closely with a flashlight even if you have good light in the room.

I don't know if you have any add-on cards (i.e. PCI for video, lan, modem etc.) but if so remove each of them and inspect them for burn marks. Also when you remove the card check the slot (usually white) for a brown burn mark.

Last check would to carefully remove the fan and or heat-sink over the CPU. Usually there are levers which move.
(you didn't say if the cpu fan worked or not) Give that part the smell test.

Next look closely at the CPU especially near the flattened corner (pin 1 location) for burn marks. Look very very closely for a possible trace mark (like a brown lightning bolt). If there is a lot of dust inside the box you should be able to see the trace in the dust.

From your initial explanation I feel that it is your mother-board which took a hit. It may have been from a voltage spike or it may have been from just a tired component.

You may also want to find the manufacturer and model of the mother-board while you have the case opened and querry around on the net on the cost of a replacement.

good luck.

#6 lolwat

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Posted 29 November 2008 - 03:17 PM

Alright, I don't have a multimeter, but when I unhooked the large white connector from my motherboard and pressed the power button on my PC the fan in the power supply didn't start up. Would that mean my power supply is out?

#7 dpunisher

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Posted 29 November 2008 - 03:56 PM

No. Your motherboard controls the on/off of the power supply. When the green wire on the connector us grounded, the power supply is switched on. It is a good idea to unplug anything hooked up to the supply when testing. No need to trash possibly good items if the power supply is faulty.

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#8 garmanma

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Posted 29 November 2008 - 05:57 PM

Caution: There are electronics inside the case that are very susceptible to electrostatic discharges. To protect your computer, touch the metal of the case to discharge yourself of any electrostatic charges your body may have stored before touching any of the components inside. As a safety precaution you should unplug the computer to avoid electrical shock.
-----------------
The purpose of this procedure is to bypass the motherboard to test the PSU.

Caution:
This procedure will involve working with live 12VDC electrical potentials which if handled improperly may lead to electrical shock. Proper precautions should also be taken to prevent electrostatic discharges (ESDs) within the case of the computer. For safety purposes please follow the instructions step by step.

First, shutdown your computer. Then unplug the power cable going into your computer.

Once you have opened the case, touch the metal of the case to discharge any static electricity.

The connector of the PSU which connects to the motherboard is readily recognizable by the number of wires in the bundle. To disconnect it you will need to press on the plastic clip to disengage it and then pull the connector up and away from the motherboard. Please take notice of the location of the locking tab and the notch on the socket of the motherboard, this will only connect one way as it is keyed. This wire bundle will have a memory of the way it has been installed and will want to bend back that direction, you may have to play around with it to find a position that the connector will stay in the same position while you run the test.

Posted Image

From the top left to right the pins are 13-24, the bottom from left to right are 1-12.


Please notice that there are PSUs with 24 pin and 20 pin connectors, the location of the green wire in the 24 pin connector is #16, and the green wire in the 20 pin connector is #14. If you look at the connector with socket side facing you and the clip on the top the number one pin will be on the bottom left corner. This makes the pin out for the 24 pin connector from left to right 13-24 on top, and 1-12 on the bottom. The pin out for the 20 pin connector from left to right is 11-20 on top , and 1-10 on the bottom. If you look at the connectors you notice that these are sockets that fit over the pins on the motherboard where the PSU cable attaches, this is where you will place the jumper. For a jumper you will need a piece of solid wire about the size of a paper clip (20-22 awg), preferably a wire with insulation. It will need to be large enough to fit firmly into the socket so that it will not need to be held in place while testing. You are at risk of electrical shock if you are holding the jumper when you power up the PSU. Insert one end of the jumper into the socket of the Green wire, and insert the other end into the socket of any Black wire.

Once the jumper is in place plug the cord back in. If the PSU is working properly the case fans, optical drives, hdds, and LEDs should power up and remain on. I would suggest that you not leave this connected any longer than is necessary for safety purposes.

To reconnect the 20/4 pin connector unplug the power cord, remove the jumper, and reconnect the connector. Take a moment at this time to make sure that nothing has been dislodged inside the case.
---------------------------
At this point you can use a DC Voltage meter to read the different rail Voltages. You will want to insert the black probe into any of the Black (-) sockets, and insert the Red (+) probe in the five different colored sockets, one at a time. Below are the five different colors and their corresponding rail Voltages. The Voltages should be within about ten percent of the given values.

Yellow +12VDC

Blue -12VDC

Red +5VDC

White -5VDC
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#9 lolwat

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Posted 02 December 2008 - 12:08 AM

Alright, thanks so far for all the help guys. Sometime in the next week or 2 I should be getting a new power supply to switch in to see if that's the problem.




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