Odd Film Capacitor Value?

Discussion in 'The Projects Forum' started by Videodrome, Dec 5, 2009.

  1. Videodrome

    Thread Starter Member

    Nov 12, 2009
    63
    0
    Hello. I need to replace a film capacitor or what i think is a film capacitor in a circuit and im having trouble with the printed value upon the part itself and finding a replacement. First off, it looks alot like a box film capacitor and is green, i dont have a photo but it looks very much like the part below. now on one side of the cap is the printing ' 1R9 ' which ive been told could mean 1.9 nf's but i can't find a place that sells them in that value. On the other side is the printing 'M1J63' but im not sure if that can tell me anything or is nothing but a factory sn or something of the ilk, then again i don't know much about this kind of thing so maybe im just not looking in the correct place.



    [​IMG]
     
  2. bertus

    Administrator

    Apr 5, 2008
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  3. tkng211

    Well-Known Member

    Jan 4, 2008
    65
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    The marking' M1J63 ' shows the rating of the film cap. The first letter M means Mega or 10 to the power 6, M1 means 1x1000000pF= 1uF. The letter'J' indicates the capacitance tolerance of +/- 5%. The last figure'63' shows the max. rated voltage of 63V. It's just a guess by the common way in marking, you need to judge or estimate the capacitor rating from the circuit (especially the rated voltage). If the capacitor is used in some RF circuit, the capacitance could be 1R9 (1.9pF). If the capacitor is used for decoupling (sometimes connected across V+ and the ground in the circuit), it could be a 1uF metallized polyester cap.
     
  4. Videodrome

    Thread Starter Member

    Nov 12, 2009
    63
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    thanks alot! will be reading for sure

    thanks alot! this really helps me out. i am now a bit more confused after getting a photo from a friend who has the same circuit that i am trying to replicate as i, but instead of the blue film cap looking circuit on mine, his looks like its been replaced with a red guy with a softer rounder shape. do film caps look like this?


    my circuit(component in question pointed at by screwdriver):
    [​IMG]
    his circuit(the red guy next to the ceramic cap)
    [​IMG]
     
  5. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    His could be a metalized poly or ceramic, or even another type. As long as it's 1uF and rated for a voltage higher than it'll be subjected to, it'll probably be OK.

    Note that if the polarity across the cap will change, the cap must be a non-polarized type; most are except for some tantalum and aluminum electrolytics.
     
  6. Audioguru

    New Member

    Dec 20, 2007
    9,411
    896
    The symbol on the metalized film capacitor looks like Epcos brand that used to be Philips and Siemens (I think). Part number B32529C0105 1uF/5%/63V. Newark or Digikey might still have them.
     
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