AC/DC Power adapter
AC/DC power adapter as known as power supply or power brick converts the high voltage AC power from a wall outlet into the low voltage DC power needed for your laptop.
The AC/DC adapter provides power for the laptop and charges the battery. It’s very important to use the right adapter for your laptop.
If you are looking for a new adapter, you should check the following:
1. Your new adapter must have exactly the same plug (adapter tip) as the original one.
2. Your new adapter must output exactly the same voltage as the original one.
3. Polarity on the new adapter’s plug must be the same as on the original one.
You can find the output voltage and amperage on the adapter’s label. As you see on the picture below, my adapter outputs 19V-3.42A.
When you buy a new adapter, you can follow this rule:
The output voltage must be the same, the amperage could be the same or higher than on the original power adapter.
For example, if my laptop requires 19v-3.42A adapter, I can safely use 19v-3.95A adapter.
HOW TO TEST OR REPAIR POWER ADAPTERS.
Most newer laptop power adapters are sealed and you cannot repair them. If the adapter is dead, you’ll have to buy a new one.
1. How can you tell if the AC adapter is dead? You can test it with a voltmeter. On the picture below I’m testing a 15V adapter and as you see the output is 15.45V. It’s pretty normal and there is nothing wrong if the output voltage is a little bit higher but if you are getting 0V, the adapter is definitely bad.
2. If you accidentally damaged the adapter plug, you can replace it with a new one. Just make sure the new plug has the same size as the old one. Cut off the old damaged plug and solder a new one. You can search for a new adapter plug (adapter tip) here.
February 20th, 2010 at 12:30 pm
Joe,
Here’s how the polarity diagram is printed on adapters.
The left one is most common.
Take a look at the old adapter, search for the polarity diagram and when you buy a new one make sure it’s the same.
February 20th, 2010 at 12:27 pm
Joe,
Yes, this adapter should work fine.
Yes, it’s very important but from my experience most adapters have the same polarity. “+” inside the barrel and “-” on the outside of the barrel.
Usually it’s printed on the adapter. There should be a diagram which shows the polarity. Let me find a picture and if I get one, I’ll post the link.
February 19th, 2010 at 8:51 pm
so i lost my ac adapter. an old one i found outputs 19v, 3.95A while my laptop requires 19v, 3.42A. so it seems like it would work, but i read from other places online to make sure the polarity is the same. i couldnt find my laptops polarity anywhere, online or printed on the laptop. is there a way to find out the polarity, or is this not necessary, since you dont seem to mention it in your article?
January 19th, 2010 at 11:43 pm
shashi,
Not sure if you can open the power adapter case without damaging it. The case is sealed and not supposed to be disassembled.
I guess you’ll have to look for a new adapter. They are cheap on eBay.
January 8th, 2010 at 3:07 am
Please tell me how to open tha casing of the AC/DC power Adapter… I have found the case that my adapter has a problem in AC adapter cable and adapter plug. So the cable component has to be replace.. But I do not know to open it, it is because there is no screw or hole for assembly the casing…
Thank you very much for your information
Tikaku
December 27th, 2009 at 9:22 am
Please tell me how I can tell whether the problem I’m having is a bad DC adapter plug or a bad DC power jack (on motherboard). The problem is that pushing the DC plug in does not always create a connection. It has to be wiggled and maneuvered for some time before a connection is established. Thanks for your help! Ken
October 27th, 2009 at 7:57 am
Keri,
What? What do you mean just AC adapter?
October 27th, 2009 at 7:35 am
If you have an AC/DC can you replace with just an AC adapter?
October 10th, 2009 at 3:02 pm
Russ,
I’ve seen hundreds of failed Toshiba adapter but never like yours. 48Volts! Are you sure that you measuring it correctly?
If your laptop requires 19 Volts, I wouldn’t plug this adapter even when the laptop is off. You can damage the motherboard.
Replace the adapter ASAP and do not use the laptop until then.
October 10th, 2009 at 11:45 am
Billy,
I don’t know, all adapters are different. You can test them with a voltmeter. Find out which one is “+” and which one is “-”.
After that take a look at the AC adapter and look for the diagram. Find out if the “+” is inside or outside the plug.
October 10th, 2009 at 9:22 am
Ok,
So I tested the voltmeter, it was giving me over double the correct voltage…. perhaps back to resoldering and a new battery.
October 10th, 2009 at 9:14 am
I checked the voltage output of my power adapter [toshiba 19V 6.3amp] and it indicated 48Volts. I am currently looking at replacing this adapter with a new one [$45.00 deleivered to my house]. This adapter has allowed me to continue working with the computer by charging the battery. I then can use the computer on battery power. It gave me a lot of the same symptoms as the failure of the power jack on the motherboard (which i re-soldered 2 years ago). I am just trying to confirm that the output is really 48 volts …. i find it hard to believe.
October 6th, 2009 at 3:10 am
I bought a replacement plug for my adapter and cut off the broken plug from my adapter. I am now ready to solder the replacement on but am unsure of which wire goes where. There are two wires, one black and one white. Could you please tell me which goes where? The laptop is a HP Pavillion DV1000.
thanks in advance for your help.
September 24th, 2009 at 6:02 pm
Trey,
To be honest, I never trusted universal adapters. You never know if they work fine for your laptop.
Buy a factory replacement adapter.
September 24th, 2009 at 9:49 am
I purchased a universal power supply and the end I need they did not have. So I cut off the end of my old one to put on the new one, but there is a blue wire in the middle of the new power supply. How do I make this work. Also there is no blue wire in the old power supply.
August 21st, 2009 at 9:53 am
Thank you. I understand. My battery may indeed still be usable! I appreciate your advice and keeping my fingers crossed! THank you, again!
August 21st, 2009 at 9:42 am
Dia,
I would suggest replacing the broken AC adapter with an original Dell adapter. Stay away for universal adapters.
My friend had a similar problem with his Dell Vostro 1500 laptop. The adapter tip broke off and instead of buying a new adapter he “fixed” the old one. After the fix the laptop was getting power but stopped charging the battery. The problem was fixed as soon as he replaced the “fixed” adapter with a brand new one.
August 21st, 2009 at 9:26 am
I have a dell inspiron laptop. The battery is failing (no longer receiving energy) and my kids broke the AC/DC adapter at the adapter end, which fits into the laptop. I tried to use electric tape to elongate the life, but tape is no longer holding. I’ve cut the black plastic covering and trimmed the silver wires, yet, there is not enough silver wire to stretch to the adapter end. Shall I replace the adapter end (and cut through the wires covered inside the white plastic, under the exposed silver wires) AND connect the new adapter to the exposed wires OR shall I purchase a universal AC/DC power supply until I can afford to buy a new battery? Please assist me! Thank you for your consideration.
July 22nd, 2009 at 10:37 am
tikaku,
The AC adapter is sealed and not repairable. You’ll have to purchase a new one. They are not expensive.
July 22nd, 2009 at 6:45 am
Please tell me how to open tha casing of the AC/DC power Adapter… I have found the case that my adapter has a problem in AC adapter cable and adapter plug. So the cable component has to be replace.. But I do not know to open it, it is because there is no screw or hole for assembly the casing…
Thank you very much for your information
Tikaku