How to Check an External Voltage Regulator

External voltage regulators are electronic assemblies that supplies electrical voltages. If a voltage regulator is part of a larger assembly such as a power supply, then the voltage regulator's designed purpose is to provide a regulated or controlled voltage to provide power. An initial step in troubleshooting any electronic device not working properly is to check the voltage from the power supply and specifically the voltage regulator. If the voltage is correct, then the electrical problem lies elsewhere. But if the voltage is not correct, then the voltage regulator is faulty or in need of adjustment.

Difficulty: Moderately Easy

Instructions

Things You'll Need:

• Multimeter
• Multimeter probes

1. Connect multimeter probes to your multimeter by observing the correct polarity. The red probe is the positive one and the black probe is the negative one. Each probe has a banana jack at its end. Plug the banana jack into the correct color plug on the multimeter input plug.

2. Set your multimeter function by selecting a function button or turning the function knob to measure voltage. Select the type of voltage as either alternating current (AC) or direct current (DC), depending on your type of voltage regulator. Most household power supplies produce a DC voltage.

3. Unplug the voltage regulator and remove any housing to gain access to the outlet terminals. Some power supplies have terminals that are accessible without removing the housing. Check to see if yours has measurement terminals. Turn on the power supply after ensuring it's plugged into the correct power source, usually a typical household circuit of 120 volts AC.

4. Touch the multimeter probes to the voltage regulator supply terminals. Make sure you observe the correct polarity if it supplies a DC voltage. Voltage regulator terminals that supply a DC voltage are usually marked with a positive (+) sign and a negative (-) sign. Touch the red probe to the positive terminal while touching the black probe to the negative terminal.

5. Read the multimeter display for the voltage regulator's output voltage.

6. After reading the voltage, remove the probes and turn off the multimeter. Unplug the power supply and put the housing back on if necessary.

Tips & Warnings

• Keep a small plastic bowl nearby when working on home electrical repairs. Keep small parts in the bowl so you don't lose them.
• Use safety precautions when working with electrical voltages. They can be dangerous and cause electrical shock.

Resources

• National Electric Code