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Total System Failure


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#1 Nickledimed

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Posted 19 July 2010 - 10:34 AM

System: AMD Athalon Opteron, 2 gig ram, 300g HDD-SATA, Win 7.
Issue: System will not power on, no fan on the power supply..NOTHING!
Story: I built a desk top for my son about 2 years ago, it has sit unused mostly, it came up fine last time I checked, it was about 3-6 months ago.
Yesterday I went to turn it on and nothing happened. Not power to the PSU fan, no respons from the system.
I checked the following:
Power outlet on wall..good
Power cable, swapped with known working one,..good
Power switch below the socket on the PSU…Set to – so this is good.
Checked all connections inside the case, all secure.
Tested…still no response.
Removed power supply from sons PC and connected it to a known working PC,.. No response.
Disconnected my sons PSU and reconnected the one on the good PC and now its doing the same thing.
Swapped the power switch cable and the reset button cable,..still nothing.

I am now at a loss, 2 systems failing.
Is there something in the motherboard that this PSU could have fried?
Any Ideas, Comments?
Thanks

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#2 MrBruce1959

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Posted 19 July 2010 - 01:39 PM

I read about your computer problem you are having above.

I am going to give you some ideas and suggestions below that may help you diagnose what the problem is.

I suggest you purchase a VOM meter for testing both AC and DC voltages, It should have the ability to test for continuity, or at least the ability to test resistance. We may be using this device later on if needed.

WARNING: THIS POST MAY CONTAIN DIRECTIONS THAT INCLUDE WORKING WITH LIVE VOLTAGES OR PARTS INSIDE A COMPUTER'S POWER SUPPLY THAT CAN CAUSE SERIOUS ELECTRICAL SHOCK OR SERIOUS BURNS, A POWER SUPPLY CONTAINS VARY LARGE ELECTROLYTIC CAPACITORS THAT ACT JUST LIKE A BATTERY OR VOLTAGE STORAGE DEVICE, THOSE AND OTHER ELECTRONICS FOUND INSIDE A POWER SUPPLY CAN STORE DANGEROUS AMOUNTS OF ELECTRICITY HOURS OR EVEN WEEKS AFTER ALL ELECTRICAL CURRENT HAS BEEN DISCONNECTED FROM THEM! PLEASE USE EXTREME CAUTION AND COMMON SENSE WHEN WORKING WITH POWER SUPPLIES OR AC VOLTAGES!

You should follow the directions below, I will post further instructions in another post that will instruct you on how to use a VOM meter found at most electronics parts stores or hardware stores.

The purpose of this procedure is to bypass the motherboard to test a ATX PSU. Some manufacturers Like Dell have used some non ATX PSUs which have a different pinout for the 20/4 pin connector, please confirm that your PSU is a ATX type before using this procedure.

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
www.playtool.com

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.


I will be waiting for your reply regarding the results of the test provided above.

I also want to provide a link to this web site, this site has useful information regarding power supplies, their connectors and the hardware found inside a computer.

Please observe the other links displayed on this page which may be helpful to you.

http://www.playtool.com/pages/psuconnectors/connectors.html

Kind regards.

Bruce.

Edited by MrBruce1959, 19 July 2010 - 01:40 PM.

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#3 Nickledimed

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Posted 19 July 2010 - 04:21 PM

Thank you for your reply.
Im using the 20 pin ATX connections.
I tried the test you described jumping between the green and a black.
Both PSU failed. no lights no fans, nothing.
Now Im wondering, if both PSU are now faulty, what could have caused them to go faulty?
My desk top worked before I connected my sons PSU to it,

Edited by Nickledimed, 19 July 2010 - 04:21 PM.


#4 MrBruce1959

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Posted 19 July 2010 - 04:43 PM

There is a possibility that a fuse blew inside both the PSU units, but if you decide to service the PSU yourself, you need to excercise the bold warning I gave you in my earlier post about lethal dangerous voltages that can be found inside a PSU, even if the power is OFF!

Bruce.

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#5 Nickledimed

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Posted 19 July 2010 - 04:48 PM

He He, Im still scratching my head.
I never hook up my desk top PSU to my sons system, I hooked his PSU up to my desk top.
So, is there something that my sons PSU could have done to both systems to cause this issue?
Is there a fuse on the motherboard that could have poped?
I know if there is I will have to figure out were it is and test it.

Edited by Nickledimed, 19 July 2010 - 04:50 PM.


#6 MrBruce1959

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Posted 19 July 2010 - 05:20 PM

It is rare to find a fuse on a motherboard.

If connecting the power supply wires to the motherboard caused a problem, there may be physical evidence of component damage.

What is confusing now, is the fact that you said that neither PSU (yours or your sons) is passing the test I provided above.

If both PSU's are now dead, or both motherboards are fried this is a rather strange occurrence.

You also have to make sure all connectors are connected correctly to the motherboard, including the power on switch on both the PSU and the computers front panel.

Make sure someone did not switch the 120/240 AC voltage switch on the PSU to the wrong setting.

Check this switch, it can be viewed from the back of the computer tower near where the power plug plugs into the tower.

Bruce.

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#7 Nickledimed

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Posted 19 July 2010 - 09:03 PM

The PSU on my system has a 115v/230v switch it is set to 115.
My sones how ever does not have this switch.
Thanks again!

Edited by Nickledimed, 19 July 2010 - 09:04 PM.


#8 MrBruce1959

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Posted 20 July 2010 - 12:22 PM

One of the ways to determine what exactly your sons PSU is doing is by going through it with the proper multimeter and test for AC on the DC output of the PSU.

You would have to really know what you are doing before you would attempt such tests on a device such as a power supply, because the voltages found inside a PSU can at the very least cause electric shock or serious burns.

The circuitry found inside a power supply, is designed to remove the AC Sine-wave, which is Alternating Current and changes it to DC which is Direct Current.
It also uses a transformer, by which the current is reduced through a network of wrapped wires around a core. The output of a transformer is a lessor sum of the original, but it still contains AC.

Note: A DIODE is a small round cylinder, it can pass current one way like a valve, but it can not pass current from its other direction, a diode is a one way valve, one way it conducts, the reverse it does not conduct. I will mention the word diode below and how the power supply uses diodes to convert AC house current 115 Volts AC to DC current that is useable for home electronics.

The reduced AC from the down-step transformer is fed into a series of diodes put together to create what is called a Bridge Rectifier, four Diodes are usually used, their polarity is ~ +~ - The two ~ symbols are the two wires coming from the transformer's output, which is still a pure AC sine-wave. The + symbol is where your DC + or Positive output is created. The - is the negative or ground output.
The + and the - go to a network of filtering, by use of very large electrolytic capacitors, these are designed to hold a charge, so that when the DC current, passes through them they keep the DC wave in a straight non alternating line, it contains no ripples like this line here -------------------------. This is an example of a pure clean DC wave, it is a straight line. Now here is an example of an unclean wave here ---v^----v^. The wave is NOT straight here. It is dirty DC current with noise in it. (Not a good example of a graph, but it gives you an idea that the line is NOT straight)

If a short circuit develops or if AC by-passes the bridge rectifier circuit, damage can result to circuits down the line that are designed for DC only.
A short circuit can be created by diodes failing and conducting in both directions, or someone has placed a coin or another small metal object into the power supply, where it creates a short, allowing dangerous AC to pass onto the main board.

Above I gave a brief easy to understand description of how a basic power supply works, I have not included the fact that one power supply can output several outputs with different voltages ratings such as +3.3 Volts, +5.0 Volts or +12.00 Volts etc.

Edited by MrBruce1959, 20 July 2010 - 12:39 PM.

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#9 abauw

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Posted 20 July 2010 - 12:59 PM

He He, Im still scratching my head.
I never hook up my desk top PSU to my sons system, I hooked his PSU up to my desk top.
So, is there something that my sons PSU could have done to both systems to cause this issue?
Is there a fuse on the motherboard that could have poped?
I know if there is I will have to figure out were it is and test it.


sometimes...defective PSU cant make lots of damage...
next time if you want to make some test...dont you ever test change it like that...but you must swap PSU from a known working PC and test it to not working PC...dont do it another way (swap PSU from not working PC to a known working pc)...
if you want test PSU working or not...you can test like bruce says...

about fuse...never find a PSU that have fuse...

check your mainboard for sign for burning components...
maybe your sons defective PSU have burn your mainboard...and your mainboard burn your PSU...or something like that...

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#10 Nickledimed

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Posted 20 July 2010 - 09:14 PM

Thanks for all that input, good info there, and good description too.
I went through both PCs, I did not smell or find anything burned.
Tomarrow I am going to totaly disassembe both PCs to get a better look at things.
Im kind of reluctant to grab anouther PSU and hook it up, because Im afraid it will do the same thing.
I guess, if I cant find anything Ill just have to purchase a new motherboard and psu and swap those parts out.
Only thing left to do now, I guess, unless someone has a better idea.




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