How to test a PSU

August 18, 2017 at 12:12:02
Specs: Windows 7

Just wondering if anyone knows how to test a proprietary HP ATX psu?
See link below for exact model.

As you can see, it only has the following connectors: 1x 4pin, 1x 6pin pci express
and 1x 6pin aux

Normally when testing a psu, I simply bridge the green and black wires on the 20 pin connector and then use a multimeter but I'm not too familiar with this psu.
Any advice much appreciated.

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August 18, 2017 at 14:47:05
Here are the 3 plugs - P1, P2, P3:

P1 - the 6-pin plug that looks like a PCIe connector is actually the main power.
P2 - the "6-pin aux" is called PS STAT but I have no idea what it is.
P3 - the 4-pin is the CPU power.

See the following:

EDIT: I did additional searching & it appears the P2 plug is the key. The following articles lists the P2 wires as:

"Black = GND
Green = PowerON (ATX standard color - when did we start doing that?)
Grey = PowerGood (again, standard color)
White = something labeled TAC - which I assume is tachometer and goes straight into the fan.
White&Red = FANCMD - yip yip yip."

message edited by riider

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August 20, 2017 at 06:43:52
Thanks for the info.

So I've tested the psu and these are the values I received.
Everything seems ok but I'm not sure about the readings for the p2 connector.
Also, during testing the psu fan is spinning full blast, is this normal?

P1 connector
blue -12v
purple 11.32v
yellow 12.17v
yellow 12.17v

P2 connector
Grey 3.31v
white 0v
white/red sripe 0v
green 0v

P3 connector
brown 12.17v
brown 12.17v

The reason I'm testing this PSU is because the pc it belongs to won't boot.
When I switch the pc on, the psu fan spins normally, hdd appears to be getting power and the mobo LEDs light up but there is no display on the monitor.
The pc then restarts and the psu fan spins full blast but nothing else happens.
I've stripped it down to the bare minimal components and tried cleaning the boards/fans, resetting the bios, replacing the memory and installing a GPU but all to no avail.

At this stage, it can only be one of the motherboard (integrated gpu), CPU or the PSU.
As I haven't got another pc or spare components to swap around I can't be sure which one it is.
If I can rule out the PSU, I'll chance my arm and get a new mobo as they're usually more likely to die than a cpu.

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August 20, 2017 at 15:28:51
Being that it's a SFF/proprietary setup, I would salvage what I could & then scrap the rest. Use the parts to build a standard size system that is upgradeable with standard off-the-shelf parts.

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