Discharging PSU so it won't kill you?

Discussion in 'General Electronics Chat' started by gloves10101, Sep 29, 2013.

  1. gloves10101

    Thread Starter New Member

    Aug 18, 2013

    I just saw a news report from 2012 saying that a boy was killed after he got electrocuted from a computer PSU he was disassembling, and the computer was unplugged. It was said that the capacitors were still charged so they killed the boy.

    Is it a true story? Does a computer PSU really have the power to kill you even when it's unplugged? If so, what do I need to do to avoid it?

  2. #12


    Nov 30, 2010
    Use 2 alligator clips to attach a resistor across each large capacitor. 27K, 2 watt and a discharge time of most of a minute.
  3. MaxHeadRoom


    Jul 18, 2013
    Personally I find that hard to believe, No.1 on the high voltage, AC input side, there is no large caps, and all the P.C. supplies I have serviced most of the caps of any significance is on the low voltage side.
    Besides, a P.C. supply is a switching supply and a largely operates with low impedance circuitry.
    Was it really unplugged?:rolleyes:
  4. studiot

    AAC Fanatic!

    Nov 9, 2007
    Refrain from poking into things without expert supervision, including electronics, if you don't understand what you are doing.
    #12 likes this.
  5. paulktreg

    Distinguished Member

    Jun 2, 2008

    Most PC power supplies have an electrolytic capacitor of about 330/470uF with 300VDC + across them on the primary side. I count this as a significant maybe others don't?
  6. THE_RB

    AAC Fanatic!

    Feb 11, 2008
    Nah, I side with Max on this one. There is a good chunk of energy in that cap, but it's unlikely to cause death from a single event 160v or 320v DC cap discharge.

    It's more likely in my opinion the boy was killed from a live PSU from a sustained exposure to AC mains voltage, which causes heart failure.

    I would fully expect someone finding the situation to have unplugged the live device and then maybe try to state it was not massive negligence on behalf of the boy (touching a live supply) but instead was "a lethal shock from the caps, even though my son was not at fault" etc.
    debe and shortbus like this.