Question about Switch-Mode PSU Conversion to Bench Supply

Discussion in 'Power Electronics' started by willgtl, Aug 2, 2015.

  1. willgtl

    Thread Starter New Member

    Sep 20, 2011
    7
    0
    A while ago I fashioned a lazy-man's bench power supply out of an old computer power supply. I simply lopped off the ATX main and grounded PS_ON with one of the 7 grounds (I don't remember why I just didn't take a couple of male pins and fashion a pluggable wire).

    Over time, I'd make a mistake and short it out and to get it to power on again I would have to ground PS_ON to a different ground. I don't know a ton about the internal workings on a switch-mode PSU but my thinking is that each ground has a thermal fuse, so when it goes the ground is no longer connected. Is my thinking correct or wrong? Thanks!
     
  2. ISB123

    Well-Known Member

    May 21, 2014
    1,240
    536
    PSU has a Fuse,PTC Thermistor and a Resistor for protection.The only reason GND isn't working anymore is if you burned the trace/wire.
     
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  3. willgtl

    Thread Starter New Member

    Sep 20, 2011
    7
    0
    Ah, thank you!
     
  4. ISB123

    Well-Known Member

    May 21, 2014
    1,240
    536
    Take a multimeter if you have and do a continuity test.
     
  5. Rahulk70

    Member

    Dec 16, 2016
    187
    3
    Hi.

    I know its a pretty old thread but I'll share similar experience I came across. I has this same issue yesterday on my Dell PSU (April 2004 mfg), accidentally shorted out my +12V and GND and the PSU shutdown immediately. Tried disconnecting from mains and reconnecting but it didn't work. So, tried disconnecting the PWR_ON(green ) and gnd and reconnected it and the PSU turned back ON. I actually just twisted the two wires since I was testing how the supply was handling different loads.
     
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