How to test a capacitor.

This article shows you how to test a capacitor using analogue multimeter. Firstly short the capacitor leads for discharging it completely. Set the multimeter to high resistance mode. Connect the multimeter terminals to the capacitor leads. For electrolytic capacitors the positive terminal of multimeter must be connected to the positive lead of the capacitor and negative terminal of multimeter to the negative lead of capacitor. For other capacitor types, polarity is not an issue.

At the moment you connect the multimeter terminals to the capacitor leads, the multimeter needle will move to zero and then slowly move towards infinity and settle there. This will happen only if the capacitor under test is healthy.

  • If the capacitor under test is short, the multimeter needle will go to zero and remain there.
  • If the capacitor under test is open, the multimeter needle will not move (will remain at the infinity position which is the initial position for analogue multi meters).
  • If the capacitor under test has leakage then the needle will first deflect to zero, and then slowly move towards infinity and will settle at a point before infinity.

This is only a rough test and for complete check up you need to varify the capacitor value using a capacitance meter.

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18 thoughts on “How to test a capacitor.

  1. Bad Ass Randy

    Very cool! Every multimeters cap tester I’ve ever had has been worthless except at very low uf and even then they suck. Yea an E.S.R. Meter would be nice but they are expensive. This is all I really need most of the time is to be able to tell if the damn cap is good or bad so thanks for the great info it is much appreciated!

    Reply
  2. seetharaman

    Hi Khanseen use 200K continuity range. one continuity direction it will quickly show low resistance and gradually increase to over range. reversing the probe it will initially show negative resistance indication reducing to minimum value and raise in positive direction to over range. if so capacitor is ok. if it is always showing some value it is defective. If the indication is always over range the capacitor is open or of very low value.

    Reply
  3. heru

    articel yang bagus tapi sebaiknya hati-hati jika kita mengukur capasitor resonan transiator horisontal karena jika kita tidak teliti mka akan selalu mmebuat trnsistor horisoantal rusak

    Reply
  4. twits4twats

    Keep up these excellent liitle tutorials John.
    For budding electronic enthusiasts this is undeniably an excellent source.

    Reply

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