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Turnining on PSU w/o plugging into mobo

B

Beeler

Junior Member
I've just done the above. It caused a blue spark and a mildly unpleasant burning smell. I wanted to know which way a fan on the bottom of the fan would blow air as my case is unusual in its design and I don't have all of the components to connect everything up before doing it.

The PSU apparently auto selects between 240 & 110 volts so this is definitely not the issue. Any thoughts on this. I'm sure people run PSUs w/o plugging into the mobo ie to power hard drives etc. Is the CPU faulty or have I screwed it up?
 
Umm. To run the psu without being connected you short the green wire with the black wire(any one IIRC). I think it's best to have at least one thing being powered by the psu when you turn it on(like a fan).
 
So do you think I have screwed it up totally or will it work if I plug into mobo/some other component which draws power? I don't really understand why not giving out any power shorts it but I'm no electrical engineer (As you can tell by my actions). Of course the PSU itself does have a fan in it which was plugged in at the time.

Obviously I don't want to end up screwing up the mobo/cpu by plugging into a fatally messed up power supply.
 
How did you turn on the PSU without a mobo? If you just used a little wire, then the spark and smell are normal. Do it properly and it should be fine.

Also, you don't need anything connected to it for it to work, it will output voltage all the same.
 
What do you mean how did I turn it on w/o mobo? Plugged in, switched on...

My current PSU doesn't create a spark and smell every time I turn it on.

Also, the fan in the PSU doesn't rotate after the spark etc. Surely it would if it was working normally?
 
A power supply should not turn on without being plugged into a mobo. You have to trick it by shorting a green and black wire on the biggest (brainfart, i forget the name) connector. I typically do it with a bent paperclip.

It is normal for a new powersupply to have an odor when it is first used. Can't say much for the spark.
 
Originally posted by: JToxic
A power supply should not turn on without being plugged into a mobo. You have to trick it by shorting a green and black wire on the biggest (brainfart, i forget the name) connector. I typically do it with a bent paperclip.

It is normal for a new powersupply to have an odor when it is first used. Can't say much for the spark.
Click to expand...

Older PSU's had switches on them which turned them on. Haven't seen them on any new ones though.

Regardless, I'd say the PSU is dead if the internal fan motor spun and now doesn't.
 
So JToxic, you're saying that I should try plugging this PSU into my mobo when all my stuff arrives and that it is likely ok?

Ducci, The fan never spun. All I got was the spark and smell.

The PSU does have its own power switch but no voltage selector as I have on my current psu now.
 
Originally posted by: Beeler
So JToxic, you're saying that I should try plugging this PSU into my mobo when all my stuff arrives and that it is likely ok?

Ducci, The fan never spun. All I got was the spark and smell.

The PSU does have its own power switch but no voltage selector as I have on my current psu now.
Click to expand...

If it never spun, then it's probably fine. Test it the way JToxic said - plug it in, touch the green and black wires with a paperclip or other wire and check to see if the fan comes on. If yes, then you're set, if no, check the switch on the back of the psu and make sure it's on. Then try again.

Another, though primative, test is to just shake the PSU a little bit. If you hear a rattling, that probably means a capacitor blew in the thing and it's dead.

Regardless, connecting it to your mobo won't hurt it, broken or not.
 
That paper clip thing sound a bit lethal with 240v mains. How do you hold the paper clip? Also, do I need to open the PSU to do this. This would void the warranty. I'm reassured you said the PSU can't damage the mobo etc so I think I'll try doing this later unless anyone thinks different?
 
It's pin 4 and 6 on the 20 pin connector.

I have a Koolance Water cooler, and before running the system, they tell you to power up the system by inserting a little wire they give you to pins 4 and 6.

If you simple plug in the power supply, and flip the switch on the back, then nothing will happen. You have to short those two pins. Check out the Koolance site, and read the manual for more info, click on the first link and read the part about testing the system by shorting the two pins.
http://www.koolance.com/support/manuals.html
 
Originally posted by: Beeler
That paper clip thing sound a bit lethal with 240v mains. How do you hold the paper clip? Also, do I need to open the PSU to do this. This would void the warranty. I'm reassured you said the PSU can't damage the mobo etc so I think I'll try doing this later unless anyone thinks different?
Click to expand...

Heh, you aren't dealing with straight AC voltage, here. The PSU steps down the voltage and converts it to DC. The black wire is 5V and the green is ground. There isn't enough voltage (or current) on the PSU cable to kill you, let alone give you a shock. The yellow one is 12V, and even that won't hurt.

We're talking about the connector wire that goes to your motherboard, by the way, no need to open the casing or anything.
 
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