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two power supplies blown in six hours by the same pc

Posted on 2003-03-23
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Last Modified: 2010-05-18
System was set up four weeks ago, an asus a7n8x(not deluxe), amd xp2700, 512 mb pc3200, radeon 9700 pro. I had sound problems since the beginning, no sound output from rear line out jack, only from front earphone jack; no sound in, neither from rear line in & mic jacks, nor from front mic jack. While trying to solve this sound problem and not being able to make awdflash.exe update my bios(followed Asustek instructions strictly), I noticed that there was a bios set up error and cpu was not properly identified and running far below it's speed (at 1263 mhz). After solving the problem and making the cpu run at acceptable speed, without overclocking (2163 mhz)the system worked for about three hours and then it blacked out. Checked the voltage at PS and only the violet and green cables of P1 connector had dc output(+5.14 & +4.38). No voltage in any other connector. I supposed it was the PS, so claimed guarantee to my pc parts supplier, who changed it for a new one. This PS brand is Duro, has a 400 watts rating (at least that's what it written on the label). The guy told me (no way to verify it) they have sold more than one thousand without any problem. Right now I'm afraid of installing another PS. Although it may be a coincidence the problem started when I corrected the CPU configuration at the BIOS.
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Question by:heryroman
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14 Comments
 
LVL 10

Expert Comment

by:Snowguy
ID: 8190904
"problem started when I corrected the CPU configuration at the BIOS" This should have nothing to do with the power supply failing. I would suspect somthing shorting on the MB to the case i.e a lost screw or no insulator on a stand off that needs to be there.
I would strip the pc down to the min.(cpu ram video) to start with and then add one device at a time booting each time to check for the problem.
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Author Comment

by:heryroman
ID: 8191626
Sorry, forgot to say... I installed the second PS, and it was blown out 3 or 4 hours later.
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Author Comment

by:heryroman
ID: 8192350
I received this answer from Extreme Tech forum, wich also seems possible:
a faulty connection in the motherboard, most probably in one of the integrated ports; when it loses contact causes a voltage fluctuation that shorts the PS.
How can I verify it?
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LVL 1

Expert Comment

by:seelus
ID: 8197988
Really sorry to see that you have fried two SMPS! As it is a new machine, I assume that the PS is ATX. If I am correct, ATX should not turn on in case of any short or overload. However, apart from motherboard, the suspectable area is the graphics card. Radeon 9700 requires a 300 W SMPS. Also see what are the other devices connected in the system. But, I am unable to suggest you how to proceed. If you are keep on experimenting, it may require few more SMPS units!

Regards,

Sreejith S
seelus@yahoo.com
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LVL 2

Expert Comment

by:darkrain
ID: 8207252
I recently blew  2 motherboards and 1 power supply, with the result being that the ATX power connector from the PSU melted into the connector on the motherboard. This was caused by a faulty power regulator on the motherboard. The system would sometimes start up and othertimes would start loading windows and then reset.

I replaced the motherboard and power supply and I have had no more problems since.
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Author Comment

by:heryroman
ID: 8207732
getting more confused with each comment, checked the mobo visually for loose contacts or faulty solderings, but seems well, checked thoroughly all components connections,jumper settings,front audio and usb connectors, etc., making sure everything was set up according to Asustek mobo manual. The second PS failed exactly as the first one, fuse is all right, but no voltage output, except from violet (5) and green(3).Have not tried another PS, since solutions provided are contradictory...
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LVL 2

Expert Comment

by:darkrain
ID: 8207781
If there is no voltage from from the red wires then that is the 12 volt line. This maybe a stupid question but is the voltage setting on the back of the PSU set correctly. ie 110 / 240 v?

If there is a fault with the M/B you will not be able to see it visably. Can you try all the compnents with a different M/B?
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LVL 12

Expert Comment

by:public
ID: 8209058
how do you know the supply is blown?
>only the violet and green cables of P1 connector had dc >output(+5.14 & +4.38). No voltage in any other connector
This is perfectly normal standby mode condition. To turn the supply on, the green wire, pin 14, must be < 0.25V, eg grounded.
It seems that you are simply not turning the supply on.
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Author Comment

by:heryroman
ID: 8214464
that's the problem, those are the voltages with the power supply turned on (obn/off switch was tested for continuity. Voltage setting is correctly and also tested.
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LVL 12

Expert Comment

by:public
ID: 8216931
Then turn the supply on by grounding the green pin14 with a piece of wire.
Obviously some of the turn on parts, the pwr button, the cable, the mb latch, or the atx connector pin 14 are bad.
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Author Comment

by:heryroman
ID: 8219869
Thank you all of you guys for your indulgence and patience, my apologies for my ignorance.
To public: It seems you are right, PS probably not the problem, have to check it at another ATX mobo. I grounded pin 14 and at least the Radeon fan made an attempt to turn,but then stopped (may be the mobo protecting itself from burning out?). It seems there is something shorting in the mobo, as Snowguy suggested. Have to check the card and the modem in another mobo to make sure; right now there are no other devices connected to it.
I"ll be away from home(well earned vacations) from tomorrow to April 7 or 8, so I won't be responding to more comments till then. Again, I appreciate your help.
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Author Comment

by:heryroman
ID: 8295737
To Snowguy and public:
Pardon me for going out on vacations and letting you hanging... While reading, remember English is my second language and the reason for any errors.
It seems Snowguy had the answer since the beginning. I stripped down the system, left only the power sw cable, When I tried to start the system by pushing the front power button, the PS fan made an attempt to turn, but just that. I verified by by crossing the power pins at the MB directly, with the same results. Having no external devices attached it seems quite clear that I got a "lemon" MB with a faulty internal problem that causes the PS to short. Anyway I would appreciate to have your feedback before sending it for a warranty claim(if I'm able to break "Asustek consumer support firewalls").There must be a bench test to determine exactly where the problem is, but I don't have those resources available.

I greatly appreciate your help and the technical knowledge I have acquired through yor wise comments. Since both of you have helped in solving the problem, and being a newcomer to this forum I'm not sure how should I award my points. Any advice?
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LVL 10

Accepted Solution

by:
Snowguy earned 580 total points
ID: 8296481
I am sory to here about your lemon MB I hope you can get it replaced.

You can post a 0 point question in Community Support
and ask them to split the points.
0
 

Author Comment

by:heryroman
ID: 8317120
Didn´t know how to do it, seems fair to me to split awarded points with "public" and grant him 45 points.Thanks for both of them for their help.
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