Testing a Voltage Regulator on a Circuit Board. Circuit boards in power supplies often have voltage regulators in order to maintain a steady voltage level. There can be other circuit boards that are not in power supplies that have voltage regulators, and these are typically used when there are other voltage sensitive components on the circuit board. Testing a voltage regulator on a circuit board is a valuable troubleshooting technique for determining if a circuit board is operating correctly or not. By measuring the correct voltage from a voltage regulator, you can have confidence that the voltage regulator portion of the circuit board is not the trouble component of the circuit.
Connect your probes to your multimeter, making sure the correct polarity is observed. The red probe should be plugged into the positive plug on the meter, while the black probe is plugged into the negative or common plug on the meter.
Set your multimeter function to measure voltage by turning the function knob to the voltage setting. Depending on what type of voltage regulator you’re going to measure, select the voltage type to either alternating current (AC) or direct current (DC).
Unplug the electrical device that has the circuit board with the voltage regulator. Remove any housing parts in order to gain access to the circuit board. Turn on the electrical device, being careful not to touch any live parts. Ensure you’re using the correct power source that the device is rated for.
Touch the multimeter probes to the voltage regulator output terminals. If the voltage regulator is an AC voltage, the polarity won’t matter. If the voltage regulator output is a DC output, put the red probe on the positive (+) terminal and the black probe on the negative (-) terminal.
Read the multimeter display for the voltage regulator’s output voltage.
Carefully remove the probes and turn off the multimeter. Write down the measurement for later reference. Unplug the device that has the circuit board in it, and put on any housing parts that you removed to gain access.