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Author Topic: trying to power a reprap  (Read 1504 times)

thatonekid

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trying to power a reprap
« on: July 23, 2012, 12:03:56 PM »
Hello all ye hackers

I was rummaging around the lab a couple nights ago looking for a power supply that could provide 48v dc output, perfect for driving a bunch of 12v steppers, and, lo and behold, i happened to find one. It is a power supply made by Unipower for a rack-mounted server. It is rated for 48v dc output at near 13 amperes. And unlike an atx power supply, no one knows how to get it to activate. It is model ETMN7000-274 not too sure about the hyphenated part.

Anywho, if you have used one of these before, or have any knowledge to give please let me know.

Also, there are two odd pins in the multi-pin connector, one is longer and one shorter than the rest.

Thanks,
Ryan Sharp
"Who needs coffee? My megalomania keeps me going just fine!"

ThantiK

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Re: trying to power a reprap
« Reply #1 on: July 23, 2012, 07:49:45 PM »
What exactly are you going to use to drive 48 volts though?  In order to get microstepping, you need a stepper motor controller, and the pololus will only do 30v.


If you can't do microstepping, then 12v is sufficient for full-stepping using a unipolar drive circuit.  You'll have resolution issues though.
« Last Edit: July 23, 2012, 07:51:20 PM by ThantiK »

f00bard

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Re: trying to power a reprap
« Reply #2 on: July 23, 2012, 08:19:25 PM »
Those power supplies came out of an old server.  Unfortunately, that server is long gone.  Going to take some gentle probing to determine how to get it to turn on, unless those connectors are some sort of standard.

thatonekid

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Re: trying to power a reprap
« Reply #3 on: July 23, 2012, 10:08:59 PM »
In response to thantik, i hadnt thought past powering it (hmmmm). However there may be lower voltage outputs on the supply.
i really just want to get the supply to power up, figuring that out would be cool.

And i am probing it gently as we speak. I have dissassembled part of tge dc side and reverse engineered it. I now have a schematic of a part of it, where i think the activation circuit is. Unfortunately it means little to me, so more probing...
"Who needs coffee? My megalomania keeps me going just fine!"

ThantiK

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Re: trying to power a reprap
« Reply #4 on: July 24, 2012, 11:39:21 AM »
Here are some hard truths when it comes to reprap building that I've learned over my short stint with it:


Don't skimp on:
Belts and Pulleys.
Stepper Motors.


You can skimp on a heated bed (though, from me...not recommended).  You can skimp on threaded rod.  You can even get away with a less-than-perfect hot end.  You can skimp a _little bit_ on linear motion by using 3D printed LM8UUs/PLA bushings and rods scrapped from scanners (but only if you get those scanners absolutely for free and your time is worthless, and you can actually find rods long enough)


http://store.kysanelectronics.com/servlet/-strse-68835/42BYGH4803/Detail are the perfect stepper motors to get.  Maybe just get 1 at a time.  X and Y first, so you got something moving around :)