HP power supply: getting it working

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OwenWatson

93 posts

Master Geek

#265332 16-Jan-2020 19:09

I've been given a HP 12v DC power supply (PS-4241-1HB) from a PC and I'm wondering how to wire it so it gives me 12V: I've put a meter between various leads and can't see 12v anywhere, so I assume that two of the 14 leads coming off the PSU have to be shorted before it generates 12v. I've looked at various sources on the net and they do say that HP PSUs vary by model in terms of what comes out of the various wires. Can anyone help?

SomeoneSomewhere

1802 posts

Uber Geek

Lifetime subscriber

#2400230 16-Jan-2020 19:47

Pictures, pictures, and more pictures.

Generally you should short ground (black) to PS_ON (green).

OwenWatson

93 posts

Master Geek

#2400245 16-Jan-2020 20:29

Hope image uploads OK?

No green and black on one plug. The thinnest wires (which I assume are the signal wires) are on P2: white-white-green-grey.

[img]https://cdn.geekzone.co.nz/imagessubs/db08d7f51478ce73cdf57d3be1432300.jpg

sparkz25

750 posts

Ultimate Geek
Inactive user

#2400272 16-Jan-2020 21:36

From memory Plug 2 the green wire needs to be tied to ground to turn on the PSU.

floydbloke

3522 posts

Uber Geek

ID Verified

#2400316 17-Jan-2020 07:10

OwenWatson:

Hope image uploads OK?

No green and black on one plug. The thinnest wires (which I assume are the signal wires) are on P2: white-white-green-grey.

Fixed. (The picture that is, not the OPs question 😄)

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OwenWatson

93 posts

Master Geek

#2401568 19-Jan-2020 11:14

It works! Many thanks.

For future reference, P1: black 0v; yellow, purple 12v; blue -12v

P3: black 0v, brown 12v

My guess is that the wire width is proportional to the max load

Are the blacks true grounds or just 0v in regard to the 12v?

Sorry, my electricity theory was 50 years ago . . .

sparkz25

750 posts

Ultimate Geek
Inactive user

#2401571 19-Jan-2020 11:16

I would say so, I can have a look and tear a spare HP Psu down later on if you want some more pics?

OwenWatson

93 posts

Master Geek

#2401575 19-Jan-2020 11:25

No need, the main thing was to get it working, the why was just a bonus.

Thanks!

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sparkz25

750 posts

Ultimate Geek
Inactive user

#2401576 19-Jan-2020 11:30

OwenWatson:

No need, the main thing was to get it working, the why was just a bonus.

Thanks!

Install a small switch on the back of the PSU where the cables come out and then chop the plugs off and you have a grunty bench supply, that's what I have done with the one I have and it comes in handy!

OwenWatson

93 posts

Master Geek

#2401577 19-Jan-2020 11:34

Bit more limited in my horizons: making a sourdough proofing box using a Peltier junction.

SomeoneSomewhere

1802 posts

Uber Geek

Lifetime subscriber

#2401642 19-Jan-2020 13:23

The blacks are almost certainly connected to the building ground. You can check with an ohmmeter between the metal chassis or the plug earth pin, and the black wires.

1101

3122 posts

Uber Geek

#2402930 21-Jan-2020 12:42

Some PSU's require a load on either the 5v or the 12v(could be either one) in order to have a stable output.
Use a dummy load resistor for that (or dont)

Ive never bother with the dummy load resistor , wasnt an issue for the PSU's I converted to 12v power supply
Also , the -12v output is usually quite low amp rated , so its of no real use .