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Cap Testing With Insufficient Tester

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    Cap Testing With Insufficient Tester

    hi

    im needing to test a 4700uf capacitor and my tester only goes up 20mf. is there a way to test it with this meter.

    thanx
    fat

    #2
    Re: Cap Testing With Insufficient Tester

    hahaha. oops. i meant 47000... but i opened the amp again and the cap is 4700uf. so now i mean delete post
    Last edited by FAT; 05-26-2017, 10:42 PM.

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      #3
      Re: Cap Testing With Insufficient Tester

      The capacitance doesn't tell you anything about how good a capacitor is. In some cases, failing capacitors can even have higher capacitance when measured while in reality.

      You can measure big capacitances using a simple resistor and a multimeter and a timer.

      See http://www.pcbheaven.com/opendir/ind...1560rud8c5dab3

      Get a power supply that has a reasonably stable voltage which is lower than the capacitor's maximum rating. Use a resistor to limit the charge rate of the capacitor .. use maybe 100 kohm or even higher.

      Put the multimeter across the capacitor and start the timer as soon as you turn on the power supply, and stop the timer when the voltage on capacitor reaches 63.2% of the power supply's voltage.

      That time in seconds is equal to R x C so your C would be t/R (Farads)


      If the capacitor charges too fast, increase the resistor value to slow the charge.

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