Things You'll Need:
- Multimeter Probes
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Step 1
Connect your multimeter probes to your multimeter. Observe the correct polarity. The red probe is the positive one, and the banana jack at its end is plugged into the red plug on the multimeter. The black probe is the negative or common probe and its banana jack is plugged into the black plug on the multimeter.
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Step 2
Set your multimeter function by turning the function knob or selecting a function button to measure voltage. Select either an alternating current (AC) or direct current (DC) voltage, depending on the output of your specific power supply. Most household power supplies produce a DC voltage.
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Step 3
Unplug the electrical device and remove any housing on the electrical appliance in order to gain access to the power supply. Being careful not to touch any of the electrical circuits, turn on the electrical device, which will also turn on the device's power supply. Make sure it is plugged into the right power source. Most household electrical appliances, other than dryers and ranges, operate by plugging into a typical 120 volt house circuit.
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Step 4
Touch the multimeter probes to the power supply output terminals. Make sure your hands stay on the insulated parts of the probes. Observe the correct polarity. Power supply output terminals are usually marked with a positive (+) sign and a negative (-) sign. Touch the red probe to the positive terminal and the black probe to the negative terminal.
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Step 5
Read the multimeter display for the power supply's output voltage.
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Step 6
After determining the voltage, remove the probes and turn off the multimeter. Unplug the electrical device and put the housing back on.
