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How to Troubleshoot a Circuit With a Multimeter

A multimeter is the most basic diagnostic tool in any electronic hobbyist's shop. It is sometimes referred to as a "VOM," for volt-ohmmeter. That's because the voltmeter and ohmmeter are a multimeter's two primary functions. More elaborate meters might also include such features as an ammeter, capacitance meter or frequency meter. While these added features increase the usefulness of the meter, they are not required to troubleshoot a circuit. Voltage readings at various test points and resistance measurements of individual components are sufficient to identify the circuit fault.

Things You'll Need

Schematic diagram of the circuit
Power supply

Instructions

- 1
  Connect the appropriate power supply and apply power to the circuit. Set the multimeter to the "Volts" position.
- 2
  Connect the "Common" (black) lead of the multimeter to the negative power supply terminal.
- 3
  Touch the red multimeter lead to each test point as indicated in the schematic. When you find a point with no voltage or a low voltage reading, stop and disconnect the power.
- 4
  Reset the multimeter to the "Ohms" position. Connect the red multimeter lead to the test point that failed the voltage test. Use the black multimeter lead to touch the opposite connection of each component that is directly connected to the test point. The faulty component will either read zero on the meter, or no reading at all.

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