The reason this topic relates to dc jack repair is sometimes when you think you have a broken charge port you might just simply have a bad power cord. This is the first thing you want to check before sending the laptop in or taking it to a repair shop. Over the years I’ve seen many cords go bad when the power jack goes bad too due to the stress people put on the tip of the power cord to try and find that sweet spot to keep their laptop running. I’ve also seen a laptop not powering on simply because the ac adapter is bad and is giving dc jack like symptoms.
The first and best way to test your cord is to use a multimeter. You can find these on amazon and ebay with a quick search and they run around $10 usd. You will use this device to see if the cord is giving off voltage. Power cords are typically rated from 18.5-20 volts when powering laptops. You need to make sure your ac adapter is giving power to the laptop before you start diagnosing anything further or replacing hardware. In the picture below you will see a typical multimeter test on a power cord. The multimeter is set to 20 VDC because that is the normal range for a laptop power cord. In the case of the picture, this was a 19.5v cord giving off 19.55 volts, so the power cord is working properly. To test it you place the ground lead on the outer part of the tip of the power cord and the red lead inside the tip as seen in the picture. You will need to make sure your multimeter is set to VDC.
If you don’t have a multimeter, you can try checking the light in the ac adapter box and see if it is lighting up. This is not an accurate way to test because the break could be at the tip of the cord or the led in the charge box can be working but the power cord is not giving off any voltage. This needs further testing to be 100% accurate but can give you an indication of a bad cord if that light if off.
If you have another power cord lying around or know someone who has one that will work with your laptop this is an obvious way to cross check your ac adapter with a known working one. You need to make sure it has the correct power requirements and tip size, so it powers the laptop and fits properly.
If you look at the next picture below you will see an hp laptop with the ac adapter plugged in and a led light coming on orange indicating it’s charging. If you have a laptop that won’t power on but the light shows that it is charging the cord is working and the laptop has a different power problem than just a bad cord.
Stephen Pomeroy is the owner of Pomeroy Computing (www.pcrepairhelp.net) and has been performing laptop and desktop pc repairs since 2005. He is an A+ certified technician with 19 years of experience in diagnosing and repairing notebook and desktop computers. He is also in his Senior year at Florida Atlantic University studying Electrical Engineering.