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PC Supply to Bench Supply

Discussion in 'General Electronics Discussion' started by schemer, Aug 11, 2012.

  1. schemer

    schemer

    27
    0
    Aug 10, 2012
    I am going to try and use an older 20 pin ATX PC power supply for a bench supply. I followed some instructions here: http://www.electronics-tutorials.ws/blog/convert-atx-psu-to-bench-supply.html and have a question. When I connect a .47ohm 5 watt power resistor it stays running but with a 1 ohm 10 watt power resistor it does not. Also the .47 ohm heats up quick and gets very hot. I only have the resistor between pins 3 and 4 and pins 14 and 15 jumped. Do I need to cut and bundle the other plugs wires (unclear if it is a must) or just get a different load resistor?
    Thanks,
    schemer
     
  2. Electrobrains

    Electrobrains

    259
    5
    Jan 2, 2012
    Hi Schemer

    I think you should bundle all cables with the same color!

    Do you have a 20 or 24 pin connector?

    What is very important is if you have a sense input (a brown cable). That cable must be connected to the orange ones!

    As is written on the linked page:
    If you have only two orange wires, you may have a brown wire instead which must be connected with the orange’s, the +3.3V for the unit to be able to power up. If you only have three red wires, another wire (sometimes pink) must be connected to them. But check this first.
     
  3. schemer

    schemer

    27
    0
    Aug 10, 2012
    Hi Electrobrains,
    I will look a little further into the project as I was just doing a quick test. It is a 20 pin ATX PS but I also have others. I just picked this one as it is more useless than the others. I wasn't sure if it was a must to cut any wires if I wanted to just use the 20 pin connector but in the end I may as well do a neat job and put some female banana plugs connections. I will report back...
    Thanks,
    schemer
     
  4. schemer

    schemer

    27
    0
    Aug 10, 2012
    Just a followup...It was a bad power supply. I grabbed another one out of my junk pile and did the same quick test with the Green and Black shorted, and the load resistor across 14 and 15 on a 20 pin plug and it works fine. Now I will replace the bulging cap and add the posts etc...
    schemer
     
  5. schemer

    schemer

    27
    0
    Aug 10, 2012
    Well now that I have connected the banana jacks etc the stupid thing goes into protection mode if I try to test a 12 volt auto flasher and 1 bulb. It works fine with just the bulb but as soon as I try to flash the bulb, the power supply protection circuit kicks in. It's always something....
    schemer

    p.s. I just bought a real power supply so I can move on...
     
    Last edited: Aug 16, 2012
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