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power supply problems?

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7 replies

by lonniec1143

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I have no power to my computer. My computer will not power up how can I check the power supply with a power meter?
Computer stoped working. Then it later started working again, and now no power at all.
Is this a power supply probem and how can I check it when it will not power up?

7 replies

by rob miners

unplug the cord from the PSU. Press a key on the keyboard for 10 seconds. Reconnect the power cord to the PSU and turn it on at the wall. If it starts up it's a faulty PSU.

If you are experiencing these problems you can test your PSU using the instructions below.

http://www.driverheaven.net/guides/testingPSU/

http://www.ochardware.com/articles/psuvolt/psuvolt.html

A quick test or use the Multimeter:

Swap the Reset connector on the Motherboard to the Power connector to rule out a faulty Power switch.

Test the Power Outlet or Power/Board by plugging in a radio or lamp.

Try another Power cord/lead if you have one.

by lonniec1143

Swap the Reset connector on the Motherboard, how is this done?
Pressing a key for 10 seconds, is this a full proof plan, how does it work?

by rob miners

or have a look at the Front Panel connectors on the Mobo for the Reset and Power connectors. They should be labled unless it is a propriatory System.

Pressing the key will dissapate the power from the capacitors on the motherboard.

by oh smeg

Look at the Flow Chart here to Fault Find

http://www.fonerbooks.com/power.htm

While it is possible to short out two pins on the ATX Connector on the PS's to check the Actual Voltages coming out of the unit unless you know what you are doing it's very difficult to actually do it safely and as we do not know which type of Power Supply that you have the directions are different.

Anyway the Voltages tell you very little under a Static Test without Load and it's very difficult to do Current Tests so that you know if the PS is actually working.

There are at least 3 Power Rails in every Power Supply with different voltages and currents 3.5, 5 and 12 V DC and all need to work to get the computer to start.

If Jacky's suggestion doesn't work you should test the system with a [b]Known Good[/b] Power Supply. But if the M'Board, HDD's or RAM/CPU has been damaged you may destroy the test PS.

Col
[i]edited[/i] for clarity I hope. ;)

by thechas

Many motherboards have an LED that lights up to show that the 5 volt standby power is present. If that LED is off, then you have a failed power supply.

If the LED is on and the computer does not power up, it could still be a bad power supply. The easy check is to swap in a different power supply with just the motherboard plugged in.

If the system still does not power up, I would suspect the motherboard.

I use this answer a lot, but I keep seeing the problem so, here goes:
Inspect the capacitors on the motherboard. (round cylinders that may be blue or tan with a silver top)If any of the caps have bulges, a raised top, or liquid leaking from them, the capacitor has failed and you need a new motherboard.

Chas

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