Need Help with Metal Film Capacitor

Discussion in 'General Electronics Chat' started by electronewb, Feb 6, 2014.

  1. electronewb

    Thread Starter Member

    Apr 24, 2012
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    I'm trying to get this right.

    I assume it's 400V? Does the dot below 400 mean anything? What's the FI stands for? And where is the capacitance value?

    And finally would those be the exact same thing as the one I have?
     
    Last edited: Feb 14, 2014
  2. crutschow

    Expert

    Mar 14, 2008
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    The 400 likely is the voltage rating.
    The capacitance is 10,000pF or 10nF or 0.01μF.
    The K likely means 10% tolerance on the capacitance value.
    The other characters may be just manufacturer's markings.
    That ebay cap looks sufficiently similar to the one you show to be a replacement.
     
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  3. electronewb

    Thread Starter Member

    Apr 24, 2012
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    Ok great thanks!! I guess I'll order 40 or 60 that's dirt cheap!! Those are part of a remote control What is the purpose of that cap on a microswitch?
     
  4. R!f@@

    AAC Fanatic!

    Apr 2, 2009
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    Suppress switching arcing, if it is used in AC mains
     
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  5. electronewb

    Thread Starter Member

    Apr 24, 2012
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    Yep it's used with 90VAC. Now what would be the reason why they don't make contact anymore? But soon as I apply heat like when I unsolder the switch and the cap the microswitch comes back to life?
     
  6. R!f@@

    AAC Fanatic!

    Apr 2, 2009
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    Could be oxidation on the contacts.
     
  7. ian field

    Distinguished Member

    Oct 27, 2012
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    When you put a capacitor across a switch that handles AC, every so often the switch closes at the voltage crest (maximum charge on the cap) - little by little this sputters the contact surfaces away.

    Generally best to put at least some resistance in series with the cap so it doesn't play spot-welder with the switch contacts.
     
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  8. electronewb

    Thread Starter Member

    Apr 24, 2012
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    OK that makes sense now I'm just wondering why heat helps cleaning the contact surfaces
     
  9. Papabravo

    Expert

    Feb 24, 2006
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    I wouldn't make book on that without testing the proposition, especially if you're going to be anywhere near the limit.
     
  10. ian field

    Distinguished Member

    Oct 27, 2012
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    Never heard of heat used to clean switch contacts - enough heat can oxidise them and form an insulating layer!
     
  11. GopherT

    AAC Fanatic!

    Nov 23, 2012
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    Copper can be cleaned using thermal shock. It is possible that very smooth surfaces will come clean with rapid heating.
     
  12. electronewb

    Thread Starter Member

    Apr 24, 2012
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    OK so I went to an electronic store they have lots of parts there and I couldn't find a 0.01uF at 400V not of that size anyways. I found a 100V that's just a bit bigger and a 600V that's almost twice the size. Even the sales guy was surprised to see that little cap to be rated for 400V. Can i use different types of caps for that applications?
     
  13. electronewb

    Thread Starter Member

    Apr 24, 2012
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    I've "cleaned" 4 so far. As soon as I try to desolder the leads and the cap it starts clicking again.
     
  14. R!f@@

    AAC Fanatic!

    Apr 2, 2009
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    Those are the types mainly used for. If you are sure it is switching 90VAC, you can suffice with 275VAC ones as they are available.

    Another type suitable is MKT box capacitors
     
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  15. electronewb

    Thread Starter Member

    Apr 24, 2012
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    Could I replace those flimsy microswitches with a solid ON OFF ON momentary toggle switch? It's for a pan & tilt controller that moves a security type camera. Right now I have a joystick ( http://www.directindustry.com/prod/apem/micro-switch-joysticks-7593-520272.html) pan left and right and tilt up and down. I think it would be more reliable to have toggle switches instead one toggle switch for the pan L & R and another toggle switch for the tilt UP & DOWN would there be an issue with the controller?
     
  16. R!f@@

    AAC Fanatic!

    Apr 2, 2009
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    Isn't tht a limit switch you showed ?

    Can you shows exactly where the switch is used
     
  17. electronewb

    Thread Starter Member

    Apr 24, 2012
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