When I work on a laptop, the first thing I always check is for proper voltage output.

Many times I have had customers bring only their laptop in and think their battery is bad – then  I plug in my universal adapter and the battery charges fine. The customer takes the laptop home and then brings it back, still thinking their battery is bad.

I always try to get them to bring the power adapter with the laptop so I can test the whole system. Voltage will vary so always check for your model’s correct voltage.

Most laptop’s power adapters put out around 19.50 volts (some less).

Let’s get started.

1. Get out your multimeter.

2. Attach red lead to the center of the jack.

3. Hold black lead to the outside of the jack.

4. Read the voltage on the multimeter.

TIP: While reading the voltage move the cord around the power jack and watch the reading on the multimeter. If the voltage remains the same then the power adapter has passed the basic test.

If the numbers on the meter go up and down then there is a break in the cord somewhere. You can get a new one or you can repair the area. On a Dell type AC adapter you need to place your red probe on the inside of the plug to get your reading.

The center pin supply’s a small voltage to the motherboard to let it know it’s a dell adapter. So if your Dell laptop complains of wrong AC adapter check if  voltage is there as this could fail and be the problem of wrong AC adapter message.

how to test laptop adapter

how to test laptop adapter



I am a part time computer programer. I use Borlands Delphi to develop windows apps. I work on computers Desktops and Laptops. Laptops are my favorite

One comment on “How To Test Your Laptop Adapter

  1. Humberto says:

    UR right, many times the costumers have brought to me their Laptops, but not the Power Supply, and in many cases the Power Supply is the culprit, so they have to return with the Adapter to be checked on the.
    Great article.

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