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need to identify this capacitor

Discussion in 'General Electronics Discussion' started by paul m, Jun 9, 2014.

  1. paul m

    paul m

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    Jun 9, 2014
    Hi, first post here, can anyone help me with identifying this capacitor? picture attached, many thanks for any help
     

    Attached Files:

  2. davenn

    davenn Moderator

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    Sep 5, 2009
    hi Paul
    welcome to the forums

    cannot quite make out what's written on it
    please type in exactly what is on the 2 lines of text
     
  3. OLIVE2222

    OLIVE2222

    690
    25
    Oct 2, 2011
    @Dave
    looks to be 14C621 on the first line
    and 52A on the second + a circled SA sign
    under there is a logo (unknown to me) with a E and a C stacked.
    @Paul
    Not sure if it's a capacitor or not, can you picture the board where it's coming from?
     
  4. davenn

    davenn Moderator

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    Sep 5, 2009

    which is exactly why I asked for a text clarification :)

    Dave
     
  5. paul m

    paul m

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    Jun 9, 2014
    hi I have added a better photo, I hope this helps
     

    Attached Files:

  6. Arouse1973

    Arouse1973 Adam

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    Dec 18, 2013
    That's a surge suppressor (MOV) and not a capacitor.
    Thanks
    Adam
     
  7. paul m

    paul m

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    Jun 9, 2014
    brilliant thank you for that, it is from a plasma power board, do you know of a way to find out its values to get a replacement?
     
  8. HellasTechn

    HellasTechn

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    Apr 14, 2013
    Exactly. Theese are called Varistors right ?
     
  9. HellasTechn

    HellasTechn

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    Apr 14, 2013

    Are you sure this is damaged ? Theese rarely go bad. You can measure its resistans with a multimeter. it should indicate "infinite" if you read low resistance then you know it is bad but in case it really is done then most probably it is note the only component on the board that is done.
     
  10. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

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    Nov 28, 2011
    MOV = metal oxide varistor. They do fail if there's a power surge (e.g. a lightning strike nearby) but when they fail, it's usually pretty obvious - chunks missing, scorch marks, etc. That one in the photo looks like it has led an uneventful life so far.

    I don't think a multimeter test would be conclusive but it's worth a try. If it reads short, it's stuffed, otherwise it's probably OK. Why do you think it's faulty Paul?
     
  11. paul m

    paul m

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    Jun 9, 2014
    it did have a black mark on the top and it looks like the black had come out from inside, nothing else looks damaged on the board.
     
  12. Arouse1973

    Arouse1973 Adam

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    Dec 18, 2013
    Kris is right. If they are designed in correctly then they should last for a long time. The mistake many people make is they think a lower rating is better. It's the opposite actually, they have a limited number full clamping cycles and the normal spikes on the mains can cause them to trigger if too low a value is chosen. This will limit their life as they became leaky and heat up and then thermal runaway takes over and bang. They should be protected by a fuse or a GDT in series. The GDT prevents the leakage current from causing any heating effects.
    Adam
     
  13. Arouse1973

    Arouse1973 Adam

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    Dec 18, 2013
    It might be damaged then. The black mark may have been caused by local heating from within the device creating a hot spot. This is how they can fail. But they can also explode, but they shouldn't catch fire because a few years ago they had to change the material the coating was made of to a self extinguishing material.
     
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