Power Supply Help - Anyone used/seen this before?

[Thazul]

I got this power supply - http://cgi.ebay.com/COMPAQ-LUCENT-U2...QQcmdZViewItem

Compaq / Lucent U24597-001 Power Supply
It says it has 56.25VDC & 15VDC Outputs

I think it's like a Computer ATX PSU, It needs a voltage looped back to stay on.
When I power it on, it powers up, fan goes strong, & I get the full 56.25VDC on my multimeter, then it powers down. I believe 2 sets of the small pins are putting out 15VDC while it is powered off.

I have searched high and low on the internet for any kind of data sheet.. All I can find are companies selling refurbs. I believe the manufacturer is Artesyn.
there is a sticker that says "Artesyn NSF1200-9630PE"
And the Compaq/Lucent Sticker saying Catalog Part Number "U24597-001 B2 L"
If anyone has any info on this thing that would be great.
Also if anyone knows where I can get a power cord for it, that would be very helpful as well

Here are some pics.

http://members.cox.net/thazul/56VDC_PSU.jpg
http://members.cox.net/thazul/56VDC_PSU2.jpg
http://members.cox.net/thazul/56VDC_PSU3.jpg


Thanks in advance,

Drew

[daedalus]

not sure what power cord that is, but looks like you could just swap the socket for a standard iec one. Have you tried powering up the psu with a suitable load attached to 56v bus? how long does it take to power down?

[Thazul]

I bought two of these, I was able to change the plug in one of the units. but the second one is all rivetted together, so I can't get inside.

I haven't tried powering it with a load yet, I'll try that.

Thanks,

Drew

[paulC]

A lot of switched mode power supplies will appear to shutdown if there is no load. It may not necessarily be the 56V supply that needs the load it could be the 15V.
Paul

[Thazul]

Well I tested load on the 56vdc output, this didn't keep it on unfortunately.
I went ahead and marked down which pins were what.
I am unsure what little pins I should try with load, have a look at my drawing.
Maybe someone out there has an idea.

This is what I found with my multimeter using the common wire grounded.

All the small pins are the lower voltage, assuming 15vdc, because that's all it says that it outputs 56.25vdc and 15vdc.

Red = Positive Voltage, Black = Negative Voltage.

http://members.cox.net/thazul/56VDC_PSU4.jpg

[posix]

don't do this before someone with the correct value comes forward.

ok so you want to connect a big chunky 1ohm 10w resistor (would someone care to suggest a better resistor to use?) from your +15vdc and connect to one of -15vdc which will place a load across the 15v circuit. this will then make the PSU stay switched on. once you got this you will be able to make use of your 56v.

[NC Cams]

Another case where Ohm's law (E=I*R) applies:

1 ohm across the 30 volts (total voltage spread across +15 and -15) will result in a 30 amps current flow if the p/s can supply that much.

Since Power = I*I*R, you'll be pulling 900 watts across a 10 watt resistor. Anyone care to roast hot dogs???

If you're going to wing it, try 100 ohms or better yet, 1K instead.

It never hurts to learn a bit of math/simple physics, especially with respect to a hobby that is SO dependant upon same....

[posix]

I couldn't be bothered to do the calculations myself and as I said: "don't do this before someone with the correct value comes forward."

NC cams I believe the 15v actually comes from +7.5 and -7.5v rather than +/-15v (as is shown in the picture above with regards to 46v being from +23 and -23) but then again I could be wrong. So it'll be 7.5amps (if connected to gnd rather than -7.5v, I DID make a typing mistake in my earlier post even though I was thinking GND) and that would be 56.25 watts so much better than the 900. not enough for hot dogs but probably enough for fried eggs a la autralian-outback-style "eggs on the rocks"

so 1K is safe then?

[James Marshall]

You all might be interested in this web site if you hane not seen it before. It showes how to convert a ATX power supply to a lab power supply. Would come in handy for 12 volt system, or could parralel or seires to make more voltage or current.

http://wiki.ehow.com/Convert-a-Compu...b-Power-Supply

[NC Cams]

IF everyone took your "...I couldn't be bothered to do the calculations myself..." attitude, you'd NEVER get the answer from ANYBODY. To even make the statement shows a clear lack of respect to those who can and more importantly WILL do the math....

Anyway, every time I put a volt meter across the +15 and -15 terminals of a p/s, I come up with a 30 volt differential. My math stands re; the power dissipation with 30 volts put across a 1 ohm resistor, Since you "...couldn't be bothered to do the calculations myself.." you are in an indefensible position to contest otherwise.

BTW: Even at +/-7.5 you're talking 450 watts which is still a LOT dissipate across a 1 ohm 10 watt resistor. it won't char broil but it will cook stuff.

I'll gladly help people who can't do the math due to lack of education - however, since the necessay formaulae were provided in a prior post, those who are interested in figuring out the answer now have the means (ergo education) to figure out the proper if not at least a reasonable alternative to my suggestion(s)...

[posix]

yes sir! thankyou sir! shall I go sit in a corner now?

[James Marshall]

NC, hi! Are you are wondering why you get 30 volts between a +15 and -15 volt supply? You would think that you get zero huh? The most likely reason is that the transformers "common" for the +/-15 volts is center taped. Going between the +/- terminals adds up the potential differences and makes the "common" unused. Note that the common is not going to be a ground. Its like putting two car batteries together in series, you get 24vdc on the outer posts, but can get 12vdc as well. Did you check out the link in post #9?