How can I test this power supply to see if it is working?

lothario · 03-26-2008, 04:46 AM

I have a power supply (with memory, NIC, keyboard and mouse) from a garage sale.
I have no spare PC to test this power supply with.

How can I test this power supply to see if it is working?
It has all the wires and molex connectors.

pixellany · 03-26-2008, 06:42 AM

Quote:

Originally Posted by lothario

How can I test this power supply to see if it is working?

With a voltmeter (aka multimeter)

You'll need to look up the interface spec. to identify the wires. Also, there is one wire which I think has to be connected to ground to turn it on. Try "pc powersupply connections" in Google.

Look thru some of the links and see if they recommend always testing with a load. Some power supplies do not like running with no load

lothario · 03-26-2008, 05:13 PM

I don't have a voltmeter.

If I connect one of the Molex connectors of this power supply
= to a spare CDROM drive
or
= to a spare hard disk

Will that power up the device?
As I remember, the Molex connectors do have ground wire.

Findus · 03-26-2008, 05:37 PM

You won't need to connect any molex connectors to power up the PSU. Simply use the paperclip trick. This will not tell you wether the PSU delivers the right voltage, but it will start the PSU and in that way give you an indication of its status.

- Findus

pixellany · 03-26-2008, 09:46 PM

Quote:

Originally Posted by lothario

I don't have a voltmeter.

If I connect one of the Molex connectors of this power supply
= to a spare CDROM drive
or
= to a spare hard disk

Will that power up the device?
As I remember, the Molex connectors do have ground wire.

The power supply has many different voltages--not all will be used by a cdrom or harddrive. To know if you have a good supply, you have to measure all the outputs.

Electro · 03-27-2008, 02:01 AM

Quote:

Originally Posted by pixellany

With a voltmeter (aka multimeter)

Some power supplies do not like running with no load

Yes that is true, but false. The power supplies that do mind no load is linear power supplies or ones with a tranformer, diodes, and voltage regulator. The power supplies of the switch-mode or switching power supplies always need a load. The minimum load depends on the power supply. About 300 to 500 milliamperes should be enough as the minimal current for most switch power supply. Computer power supplies are switch-mode.

I suggest something like Thermaltake ATX Power Supply Tester.

pixellany · 03-27-2008, 06:57 AM

<<enter quibble mode>>
I would say that the ones that need a load are those with any kind of feedback to regulate the voltage. The absence of a load can make the feedback unstable. There are both linear and switching supplies that have feedback.
<<end quibble mode>>

That tester looks like a neat thing to have---however, if I did not have a general-purpose multimeter, I would get that first.

PS: I assume the tester puts a small load on all the voltages. That IS a big convenience. I feel my "cheap filter" failing on this one....