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An odd capacitor...

Discussion in 'Hobby Electronics' started by GB, Dec 28, 2005.

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  1. GB

    GB Guest

    It was pretty easy to identify what it was that went bang,
    smelled funny, blew the power fuse for half the house and
    made the sewing machine stop working. I cracked the sewing
    maching open and found it full of electrolytic capacitor
    guts!

    What's a little more difficult is identifying what it
    is, and what to replace it with...

    Three electrolytic capacitors inside one can. Four poles
    on the capacitor - two at each end (actually only two
    connections. Physically, the can is a bit over an inch long,
    and about 3/4 inch in diameter.

    Circuit looks like this: (fixed space font, Courier New or simlar)


    O----------------------------O
    |
    ---------|
    | |
    0.2u === |
    GND-------| === 0.1u
    0.2u === |
    | |
    ---------|
    |
    O----------------------------O

    Rating is 250VAC/350VDC. No apparent polarity.

    Brand is 'Jensen Capacitors'. They're a specialst mob that make
    power caps for industrial and mains applications. Part number
    *might* be something like 'J54U' or 'E-LUX 212407'.


    Does anyone know what this is called, or where I might get one
    or something like it? It seems to be directly related to the
    electric motor / starting type thing. Died of old age methinks.

    Thanks in advance,

    GB
     
  2. Phil Allison

    Phil Allison Guest

    "GB"
    ** But it aint an electro.



    ** Likely paper/ film/ foil types .

    ( Bet the 0.2 is really 0.02 uF. )


    Just go to DSE and buy one 0.1 uF class "X2" caps and two 0.0047uF class
    "Y" caps.

    Those caps suppress RF noise interference from the brushes arcing .




    .......... Phil
     
  3. Ed -

    Ed - Guest

    remove the blown bits and plug it in

    do you really need the cap(s)?


    : It was pretty easy to identify what it was that went bang,
    : smelled funny, blew the power fuse for half the house and
    : made the sewing machine stop working. I cracked the sewing
    : maching open and found it full of electrolytic capacitor
    : guts!
    :
    : What's a little more difficult is identifying what it
    : is, and what to replace it with...
    :
    : Three electrolytic capacitors inside one can. Four poles
    : on the capacitor - two at each end (actually only two
    : connections. Physically, the can is a bit over an inch long,
    : and about 3/4 inch in diameter.
    :
    : Circuit looks like this: (fixed space font, Courier New or simlar)
    :
    :
    : O----------------------------O
    : |
    : ---------|
    : | |
    : 0.2u === |
    : GND-------| === 0.1u
    : 0.2u === |
    : | |
    : ---------|
    : |
    : O----------------------------O
    :
    : Rating is 250VAC/350VDC. No apparent polarity.
    :
    : Brand is 'Jensen Capacitors'. They're a specialst mob that make
    : power caps for industrial and mains applications. Part number
    : *might* be something like 'J54U' or 'E-LUX 212407'.
    :
    :
    : Does anyone know what this is called, or where I might get one
    : or something like it? It seems to be directly related to the
    : electric motor / starting type thing. Died of old age methinks.
    :
    : Thanks in advance,
    :
    : GB
    : --
    : "When all you have is a flamethrower, everything looks like a
    : speed camera." (Peter)
     
  4. Phil Allison

    Phil Allison Guest

    "Jasen Betts"
    Phil Allison

    ** Yes - there is a maximum value of suppression cap allowed to be
    connected from A or N to earth inside appliances.


    ** Er - no.

    It is because of ELECTROCUTION risk if a larger value is used.

    If the earth pin is not connected at the AC outlet, then the frame of the
    sewing machine becomes live because of the suppression caps. The worst case
    situation ( ie both line to ground filter caps fed from 240 AC to frame )
    must not result in more than 1mA of AC current flow.

    A pair of 0.0047uF caps meets that criterion PLUS the additional requirement
    that they be class "Y" approved types and hence have virtually ZERO chance
    of failing to a short in mains to ground service.

    Class "X" caps do not have to meed such a stringent approval and may fail
    short after a long period of use or severe spike voltage conditions.


    BTW

    I hope you are learning not to post dangerous guesses.



    ......... Phil
     
  5. Ken Taylor

    Ken Taylor Guest

    Jensen still exist:
    http://www.jensencapacitors.com/

    You could ask or try as per Phil's suggestion.

    Ken
     
  6. GB

    GB Guest

    Thanks for the advice. I visited DSE today and purchased an 0.1uF
    cap part no R2626, and a pair of 0.047uF X2 caps pn R2628 (and a bunch
    of cheap Christmas lights that I Don't Really Need(tm)!).

    Having now *properly* read your advice, I shall go back there
    tomorrow and buy the R2640 0.0047uF class Y capacitors!

    Thanks again,

    G
     
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