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  1. #1
    Super Moderator old man emu's Avatar
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    Oct 2013
    Narellan, New South Wales, Australia

    Computer ATX Power Supply adaption

    If you are building your own printer, you will need to get a power supply. I have been sourcing mine from junked computers which contain ATX type power supplies. Here is a link to the instructions that I have used successfully. Only use the black wires and yellow wires for your power output.

    Be selective about the PSUs you collect. Your printer will pull a lot of current, so always check the specs to make sure that the PSU can output more than 16 AMPS at 12 volts. If you find a PSU that puts out less than 16A, don't throw it away. Look for another PSU and connect the two in parallel as shown in the attached diagram. By connecting the PSUs in parallel, you will still get 12V, but the current (amps) will be the sum of the individual amperage outputs.

    Finally, if you salvage enough PSUs, follow the instructions in the link to turn one into a very handy workshop power supply.

    Old Man Emu
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    Last edited by old man emu; 02-15-2014 at 01:45 AM.
    You may go past me,
    But you won't outlast me!

  2. #2
    Super Moderator
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    Sep 2013
    Saskatchewan, Canada
    Might want to note that anything more recent doesn't come with the -5V rail. Manufacturers stopped including it after it was removed from the ATX spec back in 2002.

  3. #3
    Super Moderator RobH2's Avatar
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    Nov 2013
    Baltimore, MD
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    Fascinating OME. Makes total sense but never thought about parallel ATX supplies. Thanks for posting that. You could take it a step further and use them as the base for a bridge rectifier power supply for electroplating. You'd just need a circuit to attenuate the amps or volts as needed.
    Prusa i3/ Makerfarm (8" rod version) / Dual Hexagon Extruders with Itty Bitty Double Extruder, Simplify 3D Slicer.

  4. #4
    Join Date
    Dec 2016
    Sunny Florida
    ~SAFETY WARNING~ note from an Electronics Tech / Computer Tech.

    This whole "Just connect two power supplies together" REALLY not a great idea for several reasons, and SHOULD NOT BE DONE!
    No, I really don't want to get into a long discussion of it ... :-) Just wanted people to be aware of the hazards.

    In a nutshell, unless they are identical units, same model, same manufacturer they will have different power output curves. Even perfectly adjusted they will shift as the load varies. This can, and WILL cause one power supply to push current INTO the output of the other. At the least, this will eventually cause the second to fail, perhaps even taking out the second AND the printer as it dies. At the MOST it could cause one to fail catastrophically, bursting into flames.

    Since you can get one of these boxes with PLENTY of current capacity for around $25 - $30 USD you have to ask yourself if the risk is worth it to you.

    And for those who (inevitably} who will weigh in with "Well I'm doing it and it works fine!" I'll say because you CAN do something doesn't mean you SHOULD do something. You want to put your house and family at risk to avoid spending $30, fine, go for it. What do I know anyways? I'm only a factory trained power supply repair tech and Electronics Tech for 48 years, why I'm just spouting nonsense.


    Seriously people, this is NOT a solution, and if you're doing it PLEASE STOP! Besides, who's going to answer MY stupid 3D questions if you're gone? LOL!

    Peace Out and Happy New Years to all!

  5. #5
    Super Moderator curious aardvark's Avatar
    Join Date
    Jul 2014
    well old man emu did suddenLy drop of the forum.

    Plus if you buy led lighting psus, they're cheaper than atx psu's and exactly the same as 3d printer psus, just much cheaper :-)

  6. #6
    Engineer-in-Training Roberts_Clif's Avatar
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    Jun 2017
    Washington State, USA
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    If you have a bunch of ATX Power supply's and just want to use them up, you can connect your 3D Printer up like this.

    Connect the ground together on lets say 2 ATX Powers supply's. You would then use the 1st power supply to control the Controller Card and Hot-end using the smaller Supply any ATX supply should work for the amount of current you will need.

    Then you would connect the Largest Supply 20 Amp or better to the Hot Bed through an SSR-40 to control the Bed Temperature.

    Using the controller drive the input of the SSR-40 and switch the 2nd power supply to the bed using the SSR-40 Outputs.
    Now that it is figured out. You will take up more space and save about $10.00, but is can be done. Worth it maybe, maybe not.

    But actually you do not even need to connect a ground between the two supplies.
    I thought about doing this to remove the Bed and Hot-end PWM Spikes from the controller side of the power supply. Moving both Hot-end and Bed to an external supply.
    Last edited by Roberts_Clif; 01-03-2018 at 04:20 PM.

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