Home >> Hobbies >> Other Hobbies

How to Test a Capacitor With a DMM

Capacitors are electronic component that store electric charge. They come in a wide range of capacitance values and, like any electronic part, they can fail. In addition to more traditional measurements such as resistance, voltage and current, a digital multimeter, or DMM, also tests capacitance. The meter's circuitry detects the capacitor when you touch its leads with the meter probe tips. If the capacitor is good, the meter displays the capacitance value in nanofarad or microfarad units.

Things You'll Need

Screwdriver with insulated handle
Digital multimeter

Instructions

- 1
  Discharge the capacitor by grasping a screwdriver by its insulated handle and touching both of the capacitor's leads to the screwdriver's metal shaft.
- 2
  Examine the capacitor. If it has a stripe on one side and a polarity sign, such as positive (+) or negative (-), it matters how you connect the multimeter leads. Otherwise, you can connect the multimeter leads either way and obtain the same results.
- 3
  Turn the multimeter on and rotate its selector switch so it points to the capacitor measurement function.
- 4
  Touch the meter's probe tips to the capacitor leads, one probe to one lead. If the capacitor has polarity markings, touch the red probe to the positive lead and the black probe to the negative lead. It will not harm anything if you connect it in reverse, but the meter will give an incorrect reading.
- 5
  Read the multimeter's display. It may take a few seconds for the meter to measure the capacitor and settle on a steady number.

Other Hobbies