Capacitors on plug?

Discussion in 'General Electronics Chat' started by bidwin, Nov 14, 2015.

  1. bidwin

    Thread Starter New Member

    Jan 22, 2015
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    Mr. Know-nothing here again. Long time no post. I removed an IEC socket from an old computer and plan to put it in a case that will hold my power supply, chargers, and batteries used with my radio control planes. The socket has a metal bracket bracket that's connected to the ground lug, and it has what appears to be CS221K capacitors between ground and the hot and neutral lugs. See picture. Why are the capacitors there? Seems like they'd short the plug. Are the capacitors directional? Would it hurt to leave them when I put the socket in my charger case?
    Thanks,
    Charlie

    Plug.jpg
     
  2. Jony130

    AAC Fanatic!

    Feb 17, 2009
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    Last edited: Nov 14, 2015
  3. bidwin

    Thread Starter New Member

    Jan 22, 2015
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    Thanks for the response, Jony. The links were very helpful, especially the second one. I don't think I need EMI filtering for my needs. I don't see any with my power supply now, unless it's internal, and I don't want to mess with a potentially live element on my case should a capacitor short.
    Regards,
    Charlie
     
  4. KeepItSimpleStupid

    Well-Known Member

    Mar 4, 2014
    1,149
    205
    I'd leave them in. They are special capacitors known as X or Y capacitors. They are specifically designed to go across the AC line and fail in a good way.

    Here's http://www.justradios.com/safetytips.html an easy to understand blurb, I think.
     
  5. bidwin

    Thread Starter New Member

    Jan 22, 2015
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    KISS,
    Your link is the same one Jony130 sent me. If I recall correctly that link stated the caps were type Y, and if a short were to occur that could create a potentially dangerous shock condition. The link implied the risk was small but didn't say it couldn't occur.
     
  6. KeepItSimpleStupid

    Well-Known Member

    Mar 4, 2014
    1,149
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    OK. The caps do two things:
    They prevent RFI from getting in and prevent RFI from getting out. They also reduce spikes that can damage the equipment.
    I, personally have never seen one fail.

    If you use a plastic case, your totally good. Double insulated as they say.

    I'd really would leave them in.

    To give you a better idea what a "real filter is", see http://www.te.com/usa-en/product-6609060-6.html

    Some surge suppressor power strips contain comprehensive filters. e.g. Isobar. One of my favorites.
     
  7. #12

    Expert

    Nov 30, 2010
    16,346
    6,831
    The risk of those caps failing isn't even worth the effort to unsolder them. Save yourself three minutes and keep the socket looking nice and neat.:cool:
     
    KeepItSimpleStupid likes this.
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