Continuity Testing by Digital Multimeter (DMM)


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Continuity Testing is a test you can do to verify whether your circuit connections are open or closed. A Digital Multimeter (DMM) is a common tool for continuity testing.
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Most DMMs have Continuity Test Mode for testing switches, fuses, electrical connections, conductors and other components. For examples,

  • Determine whether a solder joint is good. If the solder joint is a cold solder connection, it looks like a connection but in actually it is not.
  • Determine whether a wire is broken somewhere between terminations.
  • Make sure traces on your PCB are not connected, because sometimes a solder joint will short two connections unintentionally.

This Continuity Test Mode can detect either short or open conditions extremely quickly. When the DMM detects a complete path (short), most of them will emit an audible signal (such as a beep).

Please remember when doing continuity tests:

  1. You should only do a continuity test when the device being tested is not powered.
  2. Continuity Testing is non-directional. That means you can switch probes in testing and gets the same result; keep this in mind for polarized test circuits.
  3. Very low resistance components (such as below 100ohms) and inductors are likely to test as short circuits in a continuity test, because they are very much like wires to your DMM.