1. In celebration of the launch of the new redesigned site, we just gave away a FREE antenna! Click Here to See Who Won!

when a capacitor becomes a cannon

Discussion in 'General CB Services Discussion' started by towerdog, Feb 27, 2012.

  1. towerdog one-niner-seven

    Joined:
    Nov 18, 2009
    Messages:
    599
    Likes Received:
    51
    [​IMG]

    [​IMG]


    [​IMG]



    A 600v cap in an old Teaberry boat anchor. Was working fine I was listening to some locals on 11 while wiring up a mic for it to test TX and all the sudden BOOM! What could cause this, it had only been 8 years since the radio had last been regularly used? Fortunately I grabbed the plug within seconds after and it kept receiving the entire time.
    The foil that shot out across the board was about a foot long.
     
    #1
  2. mr_fx Well-Known Member

    Joined:
    Oct 8, 2011
    Messages:
    1,474
    Likes Received:
    160
    somethings I shoot stuff across the room out of my foot long... :LOL:

    but for real that is wild.
     
    #2
  3. Beetle Well-Known Member

    Joined:
    Dec 7, 2005
    Messages:
    2,494
    Likes Received:
    358
    It's called "Rapid Energetic Disassembly". It often occurs in high-voltage capacitors such as this - ones that have seen more than a few years of service.

    Doesn't have to be an electrolytic capacitor, as this shows. It's often a good move to replace ALL capacitors except maybe the disc ceramics after 20+ years. They won't all go bad, but yours is the exception that proves the rule.
     
    #3
    1 person likes this.
  4. N8YX Active Member

    Joined:
    Mar 7, 2006
    Messages:
    241
    Likes Received:
    23
    IIRc, the old Sprague "Orange drops" were also failure-prone after a lengthy period of inactivity.
     
    #4
  5. Captain Kilowatt Professional Amateur Staff Member

    Joined:
    Apr 6, 2005
    Messages:
    11,200
    Likes Received:
    2,756
    Sometimes a capacitor's life is short for no apparent reason. Other times something else fails and draws too much current through the capacitor and it blows. Surprises the hell out of you doesn't it? :eek: Just be glad it wasn't one of these beasts. They are about three inches in diameter,aluminum end plates, ceramic case and loaded with a sticky tar like substance. When they go bang they really go BANG!!. BTW I never did get all the tar cleaned out of the transmitter that it exploded inside of. :cry:
     
    #5
  6. psycho Supporting Member

    Joined:
    Aug 25, 2006
    Messages:
    2,688
    Likes Received:
    578

    Just think about the Rapid Energetic Disassembly of a 5 farad cap in the back seat area of a Honda Civic.
     
    #6
  7. joejoenikk Member

    Joined:
    Apr 25, 2011
    Messages:
    10
    Likes Received:
    0
    !!!!!!!!CAUTION!!!!!!LETHAL!!!!!
    THAT OIL BLEW OFF IN A REAL FINE MIST!!! IT IS VERY VERY CONDUCTIVE!! And Make sure you wash it off of YOUR MULTIMETER!!
     
    #7
  8. towerdog one-niner-seven

    Joined:
    Nov 18, 2009
    Messages:
    599
    Likes Received:
    51
    yeah how come this kinda shit happens to me instead of someone who deserves it.
     
    #8
  9. psycho Supporting Member

    Joined:
    Aug 25, 2006
    Messages:
    2,688
    Likes Received:
    578

    It could have been worse, you could have been looking at it when it popped! I remember a couple of summers ago, I was washing my truck and heard a huge boom around the side of the house. First thing I thought of was that the A/C compressor had dead shorted, but it was a 55 microfarad compressor run capacitor that had exploded and the cap threw dialectric jelly and pieces everywhere plus bowed out the service panel. Took me 1 hour to clean all the shit out and replace the capacitor. $22 for a new cap and she' was up and running.
    Dangerous stuff.
     
    #9
  10. Captain Kilowatt Professional Amateur Staff Member

    Joined:
    Apr 6, 2005
    Messages:
    11,200
    Likes Received:
    2,756
    How do we know you didn't deserve it? ;)
     
    #10
  11. psycho Supporting Member

    Joined:
    Aug 25, 2006
    Messages:
    2,688
    Likes Received:
    578

    We all deserve it, must have been his turn. :laugh:
     
    #11
  12. Se7en Well-Known Member

    Joined:
    Jun 27, 2010
    Messages:
    4,600
    Likes Received:
    199
    Send some of that black magic voodoo cap bursting this way ! I deserve it !
     
    #12

Share This Page