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westoneFlag for United States of America

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Power Supply testing

Hi,
I have an IBM NetVista with a suspect Power Supply (won't POST or boot, and smells of ozone when powered on). I bought a PS tester, but it has no instructions with it. The tester will accept a 20 or 24 pin connector on one end, and 3 other types of connections on the other.

I plugged in the 20 pin connector from the PS. The tester beeped and all the LEDs except one lit up. +12v, -12v, +3.3v, PG (ground I assume), +5VSB and +5v lit green. -5v stayed dark. The PS itself lists all the voltages on its label except for the -5v. Is the tester saying the PS is good?

Thanks,
Bill
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rynox
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The tester should show lights on all connections, the lack of a -5V means that the 5V bus is likely dead, and is the root of your problem.
Most newer power supplies do not have a -5 VDC rail since that voltage is no longer used on motherboards. So absence of -5V power is normal and not a concern.

Yes, all the voltages are present that should be there.
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ASKER

That is what I was wondering, since all the other voltages were listed on the label of the PS and -5v was not. On the other hand it did smell like a bad PS. What else would smell like that? All the fans were functioning.

I am going to take it to my local IT counter this morning and have them test it. I'll let you know what they find.
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willcomp
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The PS is good. There is one capacitor in the North Bridge area that, while not burst or discolored, has a domed top. Not extremely so, but noticeable compared to the others. After unplugging everything on the MB it still won't POST. Looks like a bad MB. Thanks for the help.