Dangerous to rip parts from old PSU's?

Discussion in 'General Electronics Chat' started by Jacob J, Dec 30, 2010.

  1. Jacob J

    Thread Starter Active Member

    Jun 18, 2009
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    Hello

    Is it dangerous to rip an old power unit from a computer? I mean, is there any electricity left in the unit, like charged capasitors or something like that? The PSU's have been without any power for 6 month now.

    /Jacob
     
  2. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
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    After a few weeks, only if it is still plugged in. John
     
  3. Jacob J

    Thread Starter Active Member

    Jun 18, 2009
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    Okay, so I shoud be safe. What components to look out for if I want to be extra carefull?
     
  4. #12

    Expert

    Nov 30, 2010
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    Capacitors. They are the only thing in there that can store electricity.
     
  5. Jacob J

    Thread Starter Active Member

    Jun 18, 2009
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    Okay, but a few weeks should be enough for them to have drained off their power?
     
  6. #12

    Expert

    Nov 30, 2010
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    see post #2
     
  7. marshallf3

    Well-Known Member

    Jul 26, 2010
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    If in doubt take a clip lead and short the capacitors out. Put a 470 ohm resistor on one clip end if you don't like loud noises in case they happen to be holding a decent charge.

    In all actuality, due to the cheap caps they use in them and by design they'll all discharge in a few days max.
     
  8. TheLaw

    Member

    Sep 2, 2010
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    An old trick I learned was to unplug the computer. Then push the power button while it is unplugged. An LED may (or may not) flash on and then off quickly. This should drain the big primary cap. Some of the el cheapo caps in regular OEM power supplies have barely any capacitance at all. I've seen a 450W Acer power supply with an 168uF capacitor on the primary side. Frightening.

    That's the less technical way..There are of course more effective ways as noted above.
     
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