How to Take Voltage Measurements of Electronics

Digital voltmeters or DVMs come in a wide range of prices, and any of these will work for basic electronic troubleshooting. Whether you are taking voltage measurements in an AC or DC circuit, the process is always the same and boils down to one basic question: Is the voltage in the circuit or not? Voltage measurements are our indication that a circuit is powered and operating properly. Taking accurate voltage measurements is important because false readings will lead you to replace the wrong component or part. Try these tips to take accurate voltage measurements while you are troubleshooting an electronic circuit.

Instructions

1

Select the circuit ground or reference point. For automotive applications, this will be a connection on the chassis frame. Verify the chassis ground is clean and free of oil, dirt, rust, paint and other contaminates. Use a wire brush to clean the area of all contaminates. If you are taking a voltage measurement in an AC circuit, you will use the neutral wire (white wire) as your reference point.

2

Turn the DVM on and select the proper voltage. For automotive applications, this will be DC volts. If the meter has a DC voltage range, select 20 volts; most automobiles operate on 12-volt batteries. For AC voltage measurements, select AC volts.

3

Turn the electronic circuit on. Place the black probe on the reference point or chassis ground. Leave the probe in this location while you take your voltage measurements.

4

Place the red probe in the circuit. Monitor the voltage reading displayed on the meter. Do not short the positive probe and the negative probe while they are in the circuit.