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Power Supply Died

Discussion in 'Troubleshooting and Repair' started by Wayne Webb, Aug 15, 2016.

  1. Wayne Webb

    Wayne Webb

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    1
    Aug 15, 2016
    Hello all,
    I build CNC equipment but know very little about troubleshooting electronics. Sure could use some help.
    I have a Dual Channel 0-30V 5A Triple Output Power Supply I bought off Ebay last year, and was using it to power the nichrome cutting wire of a CNC hotwire foamcutter. It was cutting along like a dream and suddenly died, lights out, nothing. I pulled out the fuse in the back, checked it on a meter and it's good. I was running it in dual-channel mode, series, at about 52V and 4.6A. Did it short circuit just powering a nichrome resistance wire? Sorry, I don't know beans about what to do. Thanks!
     
  2. Heliman

    Heliman

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    Feb 4, 2016
    The first thing to do would be to open it up and look for any obvious signs of damage. Burnt parts, leaking capacitors etc.
     
  3. Wayne Webb

    Wayne Webb

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    1
    Aug 15, 2016
    Thanks
    Ok, on about the third inspection I do see one of the larger capacitors which has a couple of small dark-grey crusty spots on the rim on it's terminal end. I don't see any other leakage; all the other caps and components seem to be in new condition. Could that have killed the whole thing? If so, I'll pull it out and install a new one.
     
  4. 73's de Edd

    73's de Edd

    2,744
    1,131
    Aug 21, 2015
    And you KNOW, that you should have given us the brand and model number of that power supply .



    73's de Edd
     
  5. Wayne Webb

    Wayne Webb

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    Aug 15, 2016
    Arksen 305-2D
     
  6. Heliman

    Heliman

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    Feb 4, 2016
    You can pull it out and test for short or open with a ohm meter but to test for its value youd need a device that checks capacitors. Or just replace it
     
    Wayne Webb likes this.
  7. Wayne Webb

    Wayne Webb

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    Aug 15, 2016
    I have a tester for capacitance. Can it be tested while connected? The wires are soldered on.
     
    Last edited: Aug 15, 2016
  8. Heliman

    Heliman

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    Feb 4, 2016
    It will need to removed
     
    Wayne Webb likes this.
  9. Heliman

    Heliman

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    Feb 4, 2016
    If its a large filter cap be sure to discharge it
     
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  10. Wayne Webb

    Wayne Webb

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    Aug 15, 2016
    It's 50v 4700microfarad
     
  11. Heliman

    Heliman

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    Feb 4, 2016
    Filter caps are fairly large in physical size
     
    Wayne Webb likes this.
  12. Heliman

    Heliman

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    Feb 4, 2016
    Having wires connected to it, its probably a filter cap.
     
    Wayne Webb likes this.
  13. Wayne Webb

    Wayne Webb

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    Aug 15, 2016
    So that type capacitor, going bad, can kill the whole unit?
     
  14. Wayne Webb

    Wayne Webb

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    Aug 15, 2016
    This one is about .75" x 1.375''
     
  15. Heliman

    Heliman

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    13
    Feb 4, 2016
    Yes it can. It depends on the circuitry of that power supply. If its bad replace it. If the unit still doesn't work and theres no other signs of damage to components, the next step would be to obtain a schematic and start trouble shooting circuits.
     
    Wayne Webb likes this.
  16. Sunnysky

    Sunnysky

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    Jul 15, 2016
    I would suggest the supply is loaded too much for long term reliability

    Nichrome cold resistance is probably a lot less than 11.3A which means the surge current on startup depends how it is done but will exceed the power ratings and stress all the high current parts until the nichrome heats up and it's resistance increases..
     
    Wayne Webb likes this.
  17. Wayne Webb

    Wayne Webb

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    1
    Aug 15, 2016
    Someone told me to use a 120v 20A Variac. Is that safe with a bare nichrome wire?
     
  18. Wayne Webb

    Wayne Webb

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    1
    Aug 15, 2016
    My meter is reading 00.90 microfarads on the capacitor and if I hold it for a little while it reads OL (overload)
     
  19. davenn

    davenn Moderator

    13,348
    1,774
    Sep 5, 2009
    NO !
     
    Wayne Webb likes this.
  20. davenn

    davenn Moderator

    13,348
    1,774
    Sep 5, 2009
    you need to use a proper capacitance meter
     
    Wayne Webb likes this.
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