Blooming Cap.

Discussion in 'General Electronics Chat' started by R!f@@, Jul 2, 2015.

  1. R!f@@

    Thread Starter AAC Fanatic!

    Apr 2, 2009
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    And I meant literally. (About the bloomin' cap):D

    See what I mean.

    Blooming Cap.jpg

    I have never seen a capacitor open up like a flower before. o_O Have you ?
     
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  2. Randy 7140

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    Jun 17, 2015
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    Never saw one that bad, but it makes you think that the crosshair lines on the top were designed to open up like that to prevent the cap from exploding! I bet it smells too!
     
  3. cmartinez

    AAC Fanatic!

    Jan 17, 2007
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    That's a tell-tale sign that the cap is ripe and ready for harvesting ;)
     
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  4. nsaspook

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    Aug 27, 2009
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    It looks like the little alien face-hugger is about to escape from the other one too. How old is this board? Nichicon and others had a huge batch of bad caps about 10 years ago but most of the problems I see like this are heat related now.
     
  5. R!f@@

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    If I haven't seen it I believe it will result in this

    These things are like more than 5 years.
     
  6. PackratKing

    Well-Known Member

    Jul 13, 2008
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    I have mistakenly placed caps in RD circuits... RD meaning breadboarding a circuit under construction, over their rated voltage...
    This usually only boils the electrolyte, and blows the cork out of the bottom, while the plates, paper and can slam off with an ungodly vengeance in whatever directon they choose... which is why we wear face-shields... or should
     
  7. R!f@@

    Thread Starter AAC Fanatic!

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    Been there, Done that. No shield though. Bloody thing blew in my face.
    FYI, It was installed reverse.
     
    Last edited: Jul 3, 2015
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  8. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
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    The 3 others are bad too.. Just haven't ruptured yet..

    And to Randy.. Thats EXACTLY what those "crosshair" lines are for.. "Controlled rupture"
     
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  9. Randy 7140

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    Jun 17, 2015
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    I'm realizing that now that I saw that picture. I've only seen them swell in the past.....But great design for safety!!
     
  10. ian field

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    Oct 27, 2012
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    That isn't supposed to happen anymore - that's why they crease the top of the can to deliberately weaken it, so it could vent safely before it built up a head of steam.

    It was probably about the end of WW2 that wound foil electrolytics started making an impact - literally! The Reports of technicians being blinded by exploding electro's were frighteningly frequent.

    It took a few decades for them to get their act together, but all that was supposed to be behind us.
     
  11. R!f@@

    Thread Starter AAC Fanatic!

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    So why did the first caught fire.
    The venting alone did not help prevent fire.
    I was attending two more unite on the same roof and I needed to see the connection details so took the cover out of this one to find the flower.
     
  12. ian field

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    Oct 27, 2012
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    The modification to the aluminium can addressed the issue of capacitors building up pressure and exploding - I don't think fire played any part in that consideration. The only significant flammable part of an electro' is the paper separator - and that's soggy with caustic electrolyte. It would have to be arcing for a while to dry that out so it can catch fire.

    Tantalum bead capacitors OTOH: can go off like igniting match heads.
     
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