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Discharge Caps in Monitors

  1. Feb 13, 2007 #1
    My buddy works at an extremely small (4 guys and a room) computer parts recycling and disposal place. They want to be able to take apart old monitors but are afraid of the potential shock from the main caps. I am told that the voltage can get up to 25,000 volts (I'm not sure of this value) and the capacitance is between .005uF and .01uF. They just use a screwdriver to discharge the voltage, which sounds not too smart.

    Does anyone know a good resistor (power / ohm value) to use for something like this. Does anyone have any other good ideas?


  2. jcsd
  3. Feb 13, 2007 #2


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    Staff: Mentor

    The 25kV is left on the tube itself, not on external caps. The external caps might have a few 100V on them, though, so they are still dangerous. I'd think that using a 1kOhm power resistor would limit the current and give reasonable discharge times. I'd check those capacitance values that you list -- the larger electrolytic caps will be many uF, often several 100uF.

    If the caps really are just 0.01uF max, you could probably just use black ESD foam to discharge them. ESD foam is several 100kOhms per square, so you can calculate whether the discharge time constant would be practical for them.
  4. Feb 13, 2007 #3

    I'll check it out and get back to you if I have any more problems or questions.

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