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How to Test an AC/DC Adapter

AC/DC adapters convert alternating current, or AC, voltage to direct current, or DC, voltage. These adapters are also known as power supplies. Electronics manufacturers use AC/DC adapters in many types of consumer electronic devices. For example, a laptop computer uses an AC/DC "black box" to charge the computer so you can operate it from its battery reserves. Adapter sizes vary, but all adapters perform the same function. Troubleshoot a "dead" electronics device by first testing the AC/DC adapter's function.

Things You'll Need

Multimeter

Instructions

- 1
  Unplug the AC/DC adapter from the wall outlet. Unplug the adapter from the electronic device.
- 2
  Record the correct output voltage for a properly working AC/DC adapter. Locate this information on the adapter's label. Look for language such as "Output Voltage VDC."
- 3
  Turn the multimeter's range selector knob to "VDC." Plug the black lead into the jack marked "COM." Plug the red lead into the jack marked "V."
- 4
  Insert the red voltage probe into the center of the adapter's output jack.
- 5
  Plug the adapter's power cord into the wall outlet. Place the black voltage probe onto the outside ring of the adapter's output jack. Do not allow the two voltage probes to touch each other.
- 6
  Read the voltage on the multimeter's display. The AC/DC adapter is faulty if you see a lower voltage than the label specifies. Move and bend the cable near the output jack from side to side. The cable is damaged if the voltage reading fluctuates.

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