How to test a PSU without components?

Dazzeerr

Dazzeerr

New Member
Is there any way to do this? I want to check it's deffinitely not faulty before selling.

Power supply is a OCZ StealthXStream 500W.
 
PohTayToez

PohTayToez

Active Member
You can power up a PSU just by using a paperclip to jump the green wire and any black wire on the 24pin connector. If it starts up and continues running, then it's probably good. Of course the only way to be sure of 100% functionality is to power up a computer with it.
 
Machin3

Machin3

New Member
Hmm, that helped me out PohTayToez because I was wondering myself how to start a PSU with components. :)
 
linkin

linkin

VIP Member
Hey guys. not to threadjack, but I tried to test my psu by jumping the green and black wires with the power plugged in. i plugged the psu into some fans in my system, switched everything on and nothing. (only used 2 molex connections, nothing else plugged in)

is it safe to assume the PSU is dead?

I've already bought a replacement. (it's in the mail :S)
 
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PohTayToez

PohTayToez

Active Member
As soon as you jump the green and black the PSU's internal fan should start spinning which indicates that it's outputting power. If that's not happening then something is definitely wrong.
 
linkin

linkin

VIP Member
PohTayToez said:
As soon as you jump the green and black the PSU's internal fan should start spinning which indicates that it's outputting power. If that's not happening then something is definitely wrong.
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okay, thats a start. although when i plug the power cable into the psu, it "buzzes" which i think means the power is arcing over to the psu, but as you said the fan isn't spinning so yeah...
 
MacBook

MacBook

banned
PohTayToez said:
I've been doing it for about seven years now and never had a problem. It's a pretty well known trick and I've never heard of anyone blowing a power supply doing it.
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For short term testing, yet. But you don't want to leave a PSU on for an extended period of time with no load.
 
PohTayToez

PohTayToez

Active Member
MacBook said:
For short term testing, yet. But you don't want to leave a PSU on for an extended period of time with no load.
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I'm sorry, but why? I don't believe that there is any evidence to suggest that running a power supply with no load it any worse for it than running it with a load.
 
T

tyttebøvs

New Member
Such switch mode power supplies cannot work properly without a load, because of their design. You might see them just shutting off right away if there is no load.
 
MacBook

MacBook

banned
PohTayToez said:
I'm sorry, but why? I don't believe that there is any evidence to suggest that running a power supply with no load it any worse for it than running it with a load.
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Switched mode power supplies have an absolute limit on their minimum current output. They are only able to output above a certain power level and cannot function below that point. In a no-load condition the frequency of the power slicing circuit increases in speed, causing the isolated transformer to act as a Tesla coil, causing damage due to the resulting very high voltage power spikes. Switched-mode supplies with protection circuits may briefly turn on but then shut down when no load has been detected. A very small low-power dummy load such as a ceramic power resistor or 10-watt light bulb can be attached to the supply to allow it to run with no primary load attached.
 
TFT

TFT

VIP Member
MacBook said:
Switched mode power supplies have an absolute limit on their minimum current output. They are only able to output above a certain power level and cannot function below that point. In a no-load condition the frequency of the power slicing circuit increases in speed, causing the isolated transformer to act as a Tesla coil, causing damage due to the resulting very high voltage power spikes. Switched-mode supplies with protection circuits may briefly turn on but then shut down when no load has been detected. A very small low-power dummy load such as a ceramic power resistor or 10-watt light bulb can be attached to the supply to allow it to run with no primary load attached.
Click to expand...

It's usual to mention if it's a copy/paste quote from somewhere like Wiki.
 
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bomberboysk

bomberboysk

Active Member
MacBook said:
Switched mode power supplies have an absolute limit on their minimum current output. They are only able to output above a certain power level and cannot function below that point. In a no-load condition the frequency of the power slicing circuit increases in speed, causing the isolated transformer to act as a Tesla coil, causing damage due to the resulting very high voltage power spikes. Switched-mode supplies with protection circuits may briefly turn on but then shut down when no load has been detected. A very small low-power dummy load such as a ceramic power resistor or 10-watt light bulb can be attached to the supply to allow it to run with no primary load attached.
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Modern power supplies do not need a true load in order to maintain a minimum output. One shining example of this is the fan integrated into the power supply, which is run off of the +12v dc output of the power supply, and that alone can be anywhere from 3-10W draw.
 
MacBook

MacBook

banned
bomberboysk said:
Modern power supplies do not need a true load in order to maintain a minimum output. One shining example of this is the fan integrated into the power supply, which is run off of the +12v dc output of the power supply, and that alone can be anywhere from 3-10W draw.
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Typically power supply fans are fairly silent and rotate at lower RPM's then your average case fan, and the one's I've found typically draw between 1-5W. Still, it's not ideal to operate them without any additional load for an extended period of time, as I explained in my previous post.
 
ganzey

ganzey

banned
MacBook said:
Typically power supply fans are fairly silent and rotate at lower RPM's then your average case fan, and the one's I've found typically draw between 1-5W. Still, it's not ideal to operate them without any additional load for an extended period of time, as I explained in my previous post.
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doesnt matter if they are silent, they still draw power. and 5w is considered a load
 
T

tyttebøvs

New Member
It all comes down to how the psu is built. They are not all the same. They have different "minimum load" requirements. Some are also built to handle "zero load". It all depends on the psu in question.
 
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