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How can I test non-polarized capacitor?

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    How can I test non-polarized capacitor?

    I desoldered samwha NF capacitor(50v 5.6uf) from PCB circuit of 29inch CRT TV which have symptoms of no display after I heard sound of inrush of current to TV whenever I switch on this television.
    I measured ESR value of this non-polarized capacitor(samwha NF capacitor 50v 5.6uf) by means of MESR-100 ESR meter and It displayed 0.3 ohm

    And When I measured its capacitance with digital multimeter and LCR-T4 Mega328 meter, It displayed 10uf from DMM and 8uf from LCR-T4 meter.
    I found catalogue of samwha capacitor(samwha-catalogue_3.pdf file), which is attached to this thread, but there is no Tan(δ) in the characteristic entry(page 135) which is essential for ESR calculation.
    Is this non-polarized capacitor(samwha NF capacitor 50v 5.6uf) defective?
    Attached Files

    #2
    Usually, a cap with that rating in a crt tv is in the horz. yoke return path, if it was bad, you would likely have a narrow picture.

    Comment


      #3
      Originally posted by R_J View Post
      Usually, a cap with that rating in a crt tv is in the horz. yoke return path, if it was bad, you would likely have a narrow picture.
      Is it means that this non-polarized capacitor(samwha NF capacitor 50v 5.6uf) has nothing to do with symptoms of no display after I heard sound of inrush of current to TV?

      Comment


        #4
        Originally posted by chth96 View Post

        Is it means that this non-polarized capacitor(samwha NF capacitor 50v 5.6uf) has nothing to do with symptoms of no display after I heard sound of inrush of current to TV?
        Thats what I suspect, can you post the make and model or service manual? or maybe post some pictures of the board.

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          #5
          Originally posted by R_J View Post

          Thats what I suspect, can you post the make and model or service manual? or maybe post some pictures of the board.
          partnumber on the surface of main PCB and small PCB is

          MC-7CA(MAIN) 6870VM0056C(6) 980424 L.W.G(0)

          MC-7CA(CPT) 6870VS0167A(1) 971014 K.J.B(0)

          and model number of This LG CRT TV is CN-29H3

          Frankly speaking,I posted a thread about this CRT TV in the reddit forum.But It seems that there is no way to find the culprit of no display symptoms.
          https://www.reddit.com/r/Electronics...6707_regulator
          Attached Files

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            #6
            does the iinside of the tube neck glow?

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              #7
              Originally posted by stj View Post
              does the iinside of the tube neck glow?
              I have desoldered PC817 Optocoupler from PCB of this CRT TV and tested it by following below youtube tutorial.
              https://www.youtube.com/watch?v=SPSwvVpMrvc
              I confirmed that a led light turned on, But unfortunately, When I measure its resistance of pin 3 and pin 4 with10k ohm range of analogue meter, I saw that It display two reading of low resistance when checking both way.
              I think that following youtube tutorial spoiled PC817 Optocoupler, So I need to find any local store where sells it.

              Comment


                #8
                you can find optocouplers inside almost every switching psu including ones in lcd monitors

                Comment


                  #9
                  Originally posted by stj View Post
                  you can find optocouplers inside almost every switching psu including ones in lcd monitors
                  I purchased LITEON LTV817 D grade. But PC817 Optocoupler, which was defective, was C grade and made in Sharp corperation.
                  Is it Okay to replace C grade PC817 from Sharp corperation with D grade LITEON LTV817?

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                    #10
                    maybe - try it

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