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Power Supply or Mother Board?

By rcoleman ·
When I shut my computer down because I was going to be out of town for a few day everything was working fine. But, a few days later when I tried to start it back up there was nothing, no fan noise, no lights, no nothing.

QUESTION: I've tested and discovered that the Enermax power supply is putting out 5 volt on the power switch leg when I connect that lead to COM, but which two wires connect together to complete the switch leg? In other words, I'm assuming the way to test to find out if the problem is the power supply vs. the mother board is to make sure all the pins are hot when manually turned on, right?

OR, is there a better way to determine it the problem is the mother board vs. the power supply?

Thanks!

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by willcomp In reply to Power Supply or Mother Bo ...

My tried and true method is to swap power supplies.

Since I keep spares (repair shop) have never tried to test with voltmeter or power supply testers.

Dalton

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by rcoleman In reply to

Thank you for taking the time to give your opinion, and yes, if I had another power supply laying around I would certainly try this. I live in a very small town and need to special order in everything so was looking for a way to avoid the extra time and expensive of doing a lot of unnecessary experimenting.

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by sgt_shultz In reply to Power Supply or Mother Bo ...

dead box is good. think simple. iffy on/off switch? correct voltage setting on red slide switch back of power supply?. iffy power cable? reset power strip?

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by rcoleman In reply to

Thank you for taking the time to give your advice. Yes, I've tried all these options and was wanting a little more technical advice. "Thnk simple" is right on, or as I like to say, "if a bandade will do skip the major surgery."

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by TxTopgun In reply to Power Supply or Mother Bo ...

You can turn on the power suppy by shorting the green wire pin with any black wire pin. The PSU should run as long as these are shorted...release them and it should go of.

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by rcoleman In reply to

Thanks, this was exactly what I was looking for! Because answer #4 was also helpful, and because I wanted this to be worth your time, I increased the total point to 1000 so when I accept both your answers you will end up with 500 points instead of 350. I'm still sorting out the problem, but by connecting the green to the black was able to determine that the power supply is fine. Thanks again!

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by TheChas In reply to Power Supply or Mother Bo ...

The 5 volts that you measure is the 5 volt standby line.

This is normal and proper.

The ATX specification provides for 5 volts to always be present.

When you press the power button on an ATX PC, you actually signal a circuit on the motherboard to signal the power supply to startup.
If the power supply comes up correctly, another signal is sent that everything is fine, and keep the power on.

I picked up a nifty ATX power supply tester:

http://www.compgeeks.com/details.asp?invtid=ATX-PT&cat=CAS

While possible, it would be unusual for the 5 volt standby power to be okay and the power supply itself to be bad.

It could be a bad switch, power supply, motherboard, CPU, even a weak CMOS battery.

Like Dalton, I normally make an educated guess and swap parts until I find the source of the error. While not as satisfying as actually trouble-shooting the problem, it is a lot faster.

Chas

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by rcoleman In reply to

Thanks for your input! Yours and answer #3 were both very helpful, so I increased the points to 1000 so you would both end up with 500 instead of 350. I'm still sorting out the problem, but this give me a few options I hadn't considered.

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by rcoleman In reply to Power Supply or Mother Bo ...

Point value changed by question poster.

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by rcoleman In reply to Power Supply or Mother Bo ...

This question was closed by the author

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