Help Identify this Component

Discussion in 'General Electronics Chat' started by shawn8121, Feb 27, 2014.

  1. shawn8121

    Thread Starter New Member

    Feb 27, 2014
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    I need help Identifing this cap, so I can narrow down a test and or replacement.

    it appears to be a ceramic Capacitor with several marking. 404Q -135 and a letter D.
     
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  2. MrChips

    Moderator

    Oct 2, 2009
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    That is a MOV, metal oxide varistor, with a clamping voltage of 135V.
    It is used in circuit protection to limit over-voltage to 135V.
     
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  3. shawn8121

    Thread Starter New Member

    Feb 27, 2014
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    thank you so much.

    How can I test this component?
     
  4. MaxHeadRoom

    Expert

    Jul 18, 2013
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    In my experience when a MOV fails it is usually visible, IOW partially or totally destroyed, this is mostly due to it dissipating energy that exceeds its energy rating (Joules or watt-secs).
    In anything lower than the rated voltage, it will appear as a high resistance on a meter.
    Max.
     
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  5. Wendy

    Moderator

    Mar 24, 2008
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    The Completed Projects Forum is for Completed Projects only. It is meant to allow members to show plans for projects they built so other members can duplicate them if desired. New threads are also automatically moderated per Moderator review for this reason. Your thread does not belong in this forum, and was moved here.
     
  6. shawn8121

    Thread Starter New Member

    Feb 27, 2014
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    Thanks,

    Visibly it is intact, and the resistance measures out at 0.0 ohms.
     
  7. Wendy

    Moderator

    Mar 24, 2008
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    Interesting, you reported a moderator for my post. If I don't explain your mistakes how will you learn?
     
  8. R!f@@

    AAC Fanatic!

    Apr 2, 2009
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    A moderator was reported to a moderator. So who's the Senior ?

    @ OP,
    A resistance of 0 ohm is an indication of a dead MOV.
    Highly unlikely that a MOV goes short and does not rupture.
     
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  9. MaxHeadRoom

    Expert

    Jul 18, 2013
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    ??? Should read very high if a MOV.
    Max.
     
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  10. shawn8121

    Thread Starter New Member

    Feb 27, 2014
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    ok, thanks Max.


    Going to replace that component.
     
  11. ian field

    Distinguished Member

    Oct 27, 2012
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    Disc ceramic capacitors that look like that, generally have various standards symbols marked on them as they're typically used as mains input filters, and sometimes straight across the mains before the switch.

    More often than not they show visible signs of failure, similar types of resin dipped ceramic discs sometimes turn up in TV horizontal sweep tuning - I've seen a few with a small crack fringed by burn mark where they've been arcing.

    As someone else suggested it could be a MOV, but they usually shatter or crumble when they fail.

    In CRT CTVs there was usually a degauss posistor (PTC thermistor) they have a low resistance at room temperature and the resistance rises as they heat up with current flowing - some posistors were vaguely similar in appearance to the picture, but these days you'd be more likely to find a poly-fuse in that case style, simply a self resetting fuse.

    To narrow it down for sure, a bit of detective work is in order, develop a context for that part.
     
  12. MaxHeadRoom

    Expert

    Jul 18, 2013
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    Yes.. a little 'Reverse Engineering' of the associated components or immediate circuit maybe?
    Max.
     
  13. t06afre

    AAC Fanatic!

    May 11, 2009
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    Quis custodiet ipsos custodes?
    But to the OP. Can you tell more about what kind of circit this component came from
     
    Last edited: Feb 27, 2014
  14. spinnaker

    AAC Fanatic!

    Oct 29, 2009
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    That could have caused a infinite loop and brought the forum to it's knees! :eek:
     
  15. THE_RB

    AAC Fanatic!

    Feb 11, 2008
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    A forum Ouroboros? :eek:

    [​IMG] [​IMG]
     
  16. R!f@@

    AAC Fanatic!

    Apr 2, 2009
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    Custodiet ipsos Custodes sample survey.
    I got translated. Still what the heck ?

    All I can make is

    Cus to diet ip SOS custard sample survey. :confused:
     
  17. THE_RB

    AAC Fanatic!

    Feb 11, 2008
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    You need a better translator... ;)
     
  18. t06afre

    AAC Fanatic!

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    I think he used the Loosewire version:p
     
  19. R!f@@

    AAC Fanatic!

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    Care to tell me without bringing loosewire into this.

    I think he can translate better.
     
  20. t06afre

    AAC Fanatic!

    May 11, 2009
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    Veritas odium parit:cool:
     
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