TinhteDIY - Adapter is broken or lost, calmly see how to measure to find a replacement

Hello everyone, losing an adapter (power supply) is one of the "classic" problems that most of us have encountered, from Bluetooth speakers, computer monitors, Wi-Fi modems to countless other electronic devices. Rushing to buy a replacement power supply not only risks it not working, but can also permanently damage your device. This article will guide you how to read and understand the technical specifications right on the device so you can confidently choose to buy a completely correct replacement adapter. In addition, we will also learn how to perform the most basic check when the device does not turn on: use a multimeter to see if the adapter is still "alive" or not.

Part 1: Correctly Understand Power Parameters on Your Device

When you lose the original adapter, don't worry. Almost all the information you need is printed right on the device by the manufacturer, usually on the bottom or back, near the power plug location. Look for a sticker with symbols and numbers, that's how we look to buy a new adapter. Here are the most important parameters to pay attention to:

In the picture above we see the parameters: 18V - 2.8A.

1. Voltage (Voltage - V)

This is the most important factor and must be absolutely accurate. Voltage is measured in the unit Volt (V).

2. Current intensity (A)

3. Current Type (AC/DC)

You need to make sure the new adapter provides the correct type of current required by the device. Almost 100% of adapters for small electronic devices are DC type.

4. Polarity - Very Important But Easily Overlooked

This parameter applies to DC power only. It shows how the positive (+) and negative (-) poles are arranged on the power jack.

5. Jack Type

This is the physical factor. Even if all the electrical parameters are correct, if the jack doesn't fit properly, it won't work. It's best to bring the device along to try plugging it in, or take a clear photo of the jack and power hole on the device.

My jack specifications are: 5.5 x 2.5 mm.

Part 2: Quickly Check the Adapter Using a Multimeter (Multimeter)

The adapter I bought is 18.5V - 3.5A. Because the original adapter is lost, the electrical error is still within 5%. When a device suddenly doesn't turn on, the first reason we think of is usually the adapter. Before concluding that the adapter is broken, you can perform a simple measurement with a multimeter. Steps:

Turn the dial of the meter to the DC Voltage scale, denoted V⎓. Choose a measurement level one level higher than the voltage listed on the adapter. For example, if the adapter says 12V, select the 20V scale on the meter. My watch has an auto mode, so just leave it on auto to measure.

Take the red test lead (+ terminal) and poke it inside the hole of the power jack. Hold the black test lead (pole -) and make contact with the outer metal shell of the jack.

Read the results:

Conclusion

Choosing the right replacement adapter is not complicated if you master the basic rules: Voltage (V) must be equal, Current (A) can be equal or higher, and Polarity must be identical. All of this information is on your device. And know the jack specifications to match the device. You can bring the adapter with you when buying if you don't know, or take detailed photos to ask the seller. Quickly checking with a multimeter is also a useful skill to help you quickly identify the problem when the device has power problems. When shopping, if you are unsure, do not hesitate to bring your device to reputable electronic component stores to get the most accurate advice from staff.