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Bad Corsair CMPSU-550VX power supply?

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May 11, 2009 3:16:30 AM

Received my Corsair CMPSU-550VX Friday; waiting for MB delivery on Monday. In the meantime, I plugged in an Antec PSU tester (the older model: http://www.amazon.com/gp/product/images/B00006B6U0/ ). The Green LED on the tester comes on, but using a VMM, when I test the +5V pin on the Antec tester, it first goes to 5.1V upon power on, but in about 5 seconds, drops to 3.67 V. Is this a bad sign for my brand new Corsair PSU? Or is there some sort of incompatibility between it and the Antec tester?
a c 144 ) Power supply
May 11, 2009 1:51:24 PM

Cut and pasted from something I wrote a while back:

Try to verify (well as you can) that the PSU works. If you have a multimeter, you can do a rough checkout of a PSU using the "paper clip trick". You plug the bare PSU into the wall. Insert a paper clip into the green wire pin and one of the black wire pins beside it. That's how the case power switch works. It applies a ground to the green wire. Turn on the PSU and the fan should spin up.

If it doesn't, the PSU is dead. If you have a multimeter, you can check all the outputs. Yellow wires should be 12 volts, red 5 volts, orange 3.3 volts, blue wire -12 volts, purple wire is the 5 volt standby. The gray wire is really important. It sends a control signal called something like "PowerOK" from the PSU to the motherboard. It should go from 0 volts to about 5 volts within a half second of pressing the case power switch. If you do not have this signal, your computer will not boot. The tolerances should be +/- 5%. If not, the PSU is bad.


May 11, 2009 2:21:43 PM

Thanks jsc -- Trying the paper clip test you suggested, I tested all of those rails and they are OK, in particular the +5V, which is good news!

Out of curiousity, why would the Antec tester would give me different results, i.e. 3.65V on the +5V rail on the Corsair? If I use the tester on a different PSU (Earthwatts 380), the +5V is measured as 5V.
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May 13, 2009 3:07:06 AM

unprovoked said:
Thanks jsc -- Trying the paper clip test you suggested, I tested all of those rails and they are OK, in particular the +5V, which is good news!

Out of curiousity, why would the Antec tester would give me different results, i.e. 3.65V on the +5V rail on the Corsair? If I use the tester on a different PSU (Earthwatts 380), the +5V is measured as 5V.



Just to followup. I received the MB, and the Corsair was in fact bad. Would not boot MB for more than 1 second. Swap in of different PSU worked, so problem was isolated to new PSU.
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