How to Test a Laptop Power Supply

By Techwalla Contributor

A laptop power supply - also known as an A/C adapter and power brick - serves in the exact same capacity as a desktop or tower power supply in that it converts alternating current into direct current which your computer can then use. Most power bricks had an LED light that illuminates to let you know when power is available. However, even though the light may be illuminated on the power brick, there may not be enough voltage to actually charge the laptop due to damage, burn-out, or another reason. With an Ohm Meter, you can easily test an A/C adapter to see if it is supplying enough voltage.

Things You'll Need

  • Ohm Meter
  • Laptop Power Supply
  • A/C Power/Wall Outlet

Step 1

Plug the A/C adapter directly into a wall outlet. Make sure the power cable is securely inserted into the power brick.

Step 2

Locate the A/C adapter's output voltage. Voltage ratings are usually located on the bottom of the power brick.

Step 3

On the Ohm Meter, plug the red wire into the slot marked with a + sign -this is positive. Plug the black wire into the slot marked with a - sign - this is negative. Make sure to plug the ends in without the plastic handles.

Step 4

Set the Ohm Meter to DCV (Direct Current Voltage) and make sure it is set to a number higher than the voltage listed on the power supply. Usually you will set the Ohm meter to the number 50.

Step 5

Place the tip of the of the black conductor on the outside edge of the adapter.

Step 6

Place the tip of the red conductor inside the adapter.

Step 7

To verify if power is being supplied, look at the needle reading; it should land on the voltage marking near the voltage listed on the back of the power supply.

Tips & Warnings

  • You will need to purchase an Ohm Meter to test the power supply voltage. An Ohm Meter can be picked up for a few dollars at your local hardware store.
  • Please follow all safety instructions listed with your Ohm Meter prior to use.