How to test power supply

  • Thread starter Thread starter tjustin
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tjustin

I found a computer case with power supply in the trash. Of course I
always grab things like that. I happen to have a noisy fan in my PS
so U was thinking of swapping them. Of course I could just swap the
fan, but the PS I found has more wattage.

Since the person that tossed that case must have some computer
knowledge, since they removed the mobo, cards and HD. I am thinking
that the PS might be bad. I am a little afraid to just plug it to my
computer and possible do damage if it's defective. How can I test
this PS?

Thanks
 
I found a computer case with power supply in the trash. Of course I
always grab things like that. I happen to have a noisy fan in my PS
so U was thinking of swapping them. Of course I could just swap the
fan, but the PS I found has more wattage.

Since the person that tossed that case must have some computer
knowledge, since they removed the mobo, cards and HD. I am thinking
that the PS might be bad. I am a little afraid to just plug it to my
computer and possible do damage if it's defective. How can I test
this PS?

Thanks
Click to expand...

Your local computer shop probably sells a PSU tester for around $20 or
less. Use it with all power leads disconnected from their components.
Good luck.
 
I found a computer case with power supply in the trash. Of course I
always grab things like that. I happen to have a noisy fan in my PS
so U was thinking of swapping them. Of course I could just swap the
fan, but the PS I found has more wattage.

Since the person that tossed that case must have some computer
knowledge, since they removed the mobo, cards and HD. I am thinking
that the PS might be bad. I am a little afraid to just plug it to my
computer and possible do damage if it's defective. How can I test
this PS?

Thanks
Click to expand...

How would you build trust in that supply ?

You could walk out of the room, come back, and find a
fried computer.

Supplies are dangerous enough, when you get them new :-)

I test mine with a load box. That is a box with resistors in it.
I built my own. It draws, like, 100W or so. I connect the PSU
to it and run it for a couple hours, before using it on a new
motherboard. The purpose of that, is to weed out supplies that
are bad out of the box. I check the voltages with a multimeter,
while the supply is connected to the load box. All voltages have
to be well within the +/-5% deviation limits.

Testing on the load box doesn't guarantee anything, as it could
catch fire at the three hour mark if it feels like it.

The supply in that discarded case, could simply be thrown out
because the owner got a bigger one. But it could also be thrown
out because it fried something.

The little power supply tester dongles you can buy, only put a
small load on one rail, like the +5V. So that isn't much of a
test. You'd need to use a multimeter to measure the voltage on
the pins, to get some idea as to whether it is safe to connect
to a computer. By the time you'd paid for all the toys needed
to do the test, you could just have bought a supply. To build
another load box, would probably cost me anywhere from $50 to
$100, depending on where I get the power resistors.

Paul
 
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