How to test a power supply???

[advanced]

whats the easiest way using a multimeter?

 

[dma0991]

There are better ways to test a PSU like using a PSU tester. The only drawback is that it is a single purpose device unlike a multimeter but it does simplify testing the PSU. Easiest way would be to actually plug everything in and see if it works or just use the paperclip method to jumper 2 wires which would start the PSU.

http://www.newegg.com/Product/Produc...-002-_-Product

 

[Zap]

Those cheap PSU testers only test that the unit will power on, and will output roughly the right voltages while having near zero load. This won't tell you how the PSU behaves in a system. I've seen times when these "testers" passed a PSU, but the PSU was degraded enough to not be able to run an actual computer.

 

[PreferLinux]

The only way to test a PSU is to use a special device to fully load it while using an oscilloscope to measure the voltage and ripple. Otherwise, you don't find out if it is really any good.

There is a sticky about how to measure your PSU voltages if that is what you want.

 

[Minerva]

Those cheap PSU testers only test that the unit will power on, and will output roughly the right voltages while having near zero load. This won't tell you how the PSU behaves in a system. I've seen times when these "testers" passed a PSU, but the PSU was degraded enough to not be able to run an actual computer.

This. I have an old 700W Seasonic that does this. Put it in a system and the video card freaks out. BIOS reads as high as 16V for 12V and 2.4V for 3.3V! Yet jumping green to black and checking wires with a VOM shows typical voltages. This thing torched a 280GTX because of this!

 

[PreferLinux]

This. I have an old 700W Seasonic that does this. Put it in a system and the video card freaks out. BIOS reads as high as 16V for 12V and 2.4V for 3.3V! Yet jumping green to black and checking wires with a VOM shows typical voltages. This thing torched a 280GTX because of this!

But what are the load voltages with a multimeter?

 

[Minerva]

But what are the load voltages with a multimeter?

Load tests fluctuated all over the place with +12V being the worst (as high as 17V recorded!). The 24pin ATX connector was also burned as well. Fortunately the rest of the system fared OK. RIP 280GTX.

(New 580GTX humming along nicely now!)

 

[bryanl]

While the computer is running.

 

[LiuKangBakinPie]

Group all of the power cables and connectors together
recommend rerouting them and pulling them as far away from the computer case as possible. This will make it as easy as possible to test the power supply connections.
Short out pins 15 and 16 on the 24-pin motherboard power connector with a small piece of wire (green and black normally)
Plug in the psu
Set your multimeter to VDC. If the meter doesnt have a auto range set it to 10.00v
Test the mobo 24 pin connector first by connecting negative probe on the multimeter (black) to any ground wired pin and connect the positive probe (red) to the first power line you want to test.
24 pin got a +3.3 VDC, +5 VDC, -5 VDC (optional), +12 VDC, and -12 VDC lines across multiple pins. look for any voltages outside the approved tolerance
Unplug it from the wall
reconnect your internal devices remove the short plug in the 24 pin in the mobo
plug it in then test the connectors for your devices simple

Ps I do not take responsibility for any ellectrical shock nor bush fires you might start.

 

[VirtualLarry]

Short out pins 15 and 16 on the 24-pin motherboard power connector with a small piece of wire (green and black normally)

Do you do this temporarily, or do you have to hold them shorted, in order to keep the PSU running?

 

[fffblackmage]

Short out pins 15 and 16 on the 24-pin motherboard power connector with a small piece of wire (green and black normally)

Do you do this temporarily, or do you have to hold them shorted, in order to keep the PSU running?

It sounded like you keep it shorted:

...
reconnect your internal devices remove the short plug in the 24 pin in the mobo

But LiuKangBakinPie, your instructions are for testing the PSU with no load? What's the point of that?

 

[PreferLinux]

None, and it is possible to damage the PSU too.

 

[LiuKangBakinPie]

Do you do this temporarily, or do you have to hold them shorted, in order to keep the PSU running?

you have to stuck a pin in there then put tape over it so it wont fall out to get the psu started.

 

[LiuKangBakinPie]

It sounded like you keep it shorted:


But LiuKangBakinPie, your instructions are for testing the PSU with no load? What's the point of that?

read both parts. first the psu. then you connect the devices.

 

[LiuKangBakinPie]

None, and it is possible to damage the PSU too.

with a multimeter?

 

[VirtualLarry]

read both parts. first the psu. then you connect the devices.

No, for most PSUs, there MUST be a load on the +12V line, otherwise it may fly out of regulation. Connect a fan or two, BEFORE you jumper the green pin with a black pin.

 

[Meghan54]

No, for most PSUs, there MUST be a load on the +12V line, otherwise it may fly out of regulation. Connect a fan or two, BEFORE you jumper the green pin with a black pin.

You really can't make that blanket statement any longer. Almost all DC-to-DC conversion ps's require no load being placed on any rail to turn on safely.

But, you're right, the older the ps you look at, the more minimum load is required.....some older ones even need loads on all three rails, not just the +12V.

You have to look at each ps's label to determine if a load is required or not.