motherboard or power?

[brightstar]

hi,
i had a knackered power supply, but i didnt know this until i had every other piece of my pc tested inc. the motherboard, cpu and memory. so i just bought a new power supply wired it up and... nothing.

power button doesnt do anything.

how do i know if its the power switch connection on the motherboard? is there another way to turn on the motherboard? or test the power supply?

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[franklin97355]

If you short the pins on the motherboard with a metal object (ATX power supply ONLY!) it should start. There are also power supply testers you can buy to test the supply connections.

The answer is "42"

 

[BadFrog]

Most likely a bad power switch. Follow Franklin's advice about shorting the pins and it should boot right up.

"Once you can accept the universe as matter expanding into nothing that is something, wearing stripes with plaid comes easy"
Albert Einstein

 

[brightstar]

er... sounds a bit risky but what the hey! thanks i'll give it a try tonight.

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[G0AOZ]

We're talking very low voltage and minimal current here, so virtually no risk at all. This should be a momentary contact, not a permanent short.

ROGER - G0AOZ.

 

[brightstar]

nope, nothing.

any other ideas? or am i going to have to get this PSU tested as well? what are the chances of me buying two dodgy PSUs from the same place, in a row???

where would i find myself one of these testers?

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[lb63640]

Brightstar, I bought a power supply tester from TigerDirect.com for around $14, and it does the trick for me.

 

[maharlika1]

Check if your motherboard LED was on. This indicate that your ATX power supply was working and have Standby DC output for motherboard. If its LED was OFF, plug your pc w/ known good A.C.Outlet. You can test your motherboard by momentary shorting w/ screwdriver 2 pins labeled "PWR SW".

 

[edfair]

Without the standby supply working the front panel switch or screwdriver can't turn the system on.

The output of the standby power up circuit puts 0v on pin 14 (usually green wire in the ATX harness) bringing the rest of the supply up.

You may wish to verify that the Molex 20 pin block is fully seated on the M/B. They are hard to seat when new.

Ed Fair
Give the wrong symptoms, get the wrong solutions.

 

[paparazi]

It is very possible that the "bad" PSU caused a spike shorting a component to ground (typically a hard drive or CDrom drive)
Pull the molex connectors off all your roms/HDD's it might also be worth checking the smaller connector on the floppy (I've seen many a time when these have been forced on bending pins on the floppy drive)
Also disconnect all addon cards and unecessary periferals
If you get "POST" then you can then work backwards to find the offending item.
Martin


We like members to GIVE and not just TAKE.
Participate and help others.

 

[BadBigBen]

I would like to add to Paparazi's post:

I've seen PC's where the IDE cable was the culprit, so you should pull the IDE cables OFF the MoBo, not just from the DRIVES... then follow Paparazi's suggestion...

Ben

"If it works don't fix it! If it doesn't use a sledgehammer..."