Test Laptop AC Power Adapter with Multimeter by Britec
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- Опубліковано 7 вер 2024
- Test Laptop AC Power Adapter with Multimeter by Britec
Let's say your laptop does not start at all. You plug in the power adapter and press on the power button, but the laptop will not react. It's dead and the power or battery charge LED will not light up.
What could be wrong? Is it bad power jack or the motherboard is dead?
First of all, test the AC/DC power adapter with a multimeter. It's possible that there is noting wrong with the laptop and your problem is related to the power adapter.
Need help with your computer?
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Important - When using a multi-meter to check voltage across the adapter, be sure to understand that the "brick" actually functions as a transformer. In other words, it converts AC power from the wall receptacle to DC power because the laptop battery is actually a DC battery.
When checking voltage in the end of cord between the wall receptacle and where it connects to the "brick", be sure to set your multi-meter to ACV (AC Volts). 600V in UK and 200V in the U.S.
If this checks out ok, you will need to reconfigure the multi-meter to check output voltage at the pin connector which is the connector (usually colored) that plugs directly to the laptop. When checking output voltage from the transformer or "brick" be sure to change the setting on the multi-meter to DCV or DC Volts....20V specifically for most meters. After changing the multi-meter to DCV, Insert one prong/lead from the multi-meter into the pin connector and touch the other prong/lead to the outside of the pin connector as demonstrated in the video.
For diagnostics just remember: AC Power before the "brick" / DC power after the "brick".
What is the brick is just passing the AC without converting? Can this happen? If so then, using DC on multimeter to check the voltage on the plug end would break multimeter?
This is such a clear explanation. You got a gift! I want to mention my brother advised me to pay attention to the little linier diagram that has a + on one end a dot in the middle with a C over it and a minus - sign on the other end. Especially when attempting to replace the adapter with something you might have lying around.
That's for the tips and advise Patrick, there is always something I miss.
Thanks for this video from Texas. Found out that my charger is bad and I didn't have to buy a new laptop. Cheers!
Blessings brother, the paper clip was exactly what I needed to test the DC on my charger!
Thanks for the clear information and demonstration.
I'm sure that it will come is use for those wary of using a multimeter with things connected to a live ac socket.
I'd love to see a video showing how you can measure the power being used by a laptop/NUC during varying loads of usage to illustrate that despite an ac adapter having a certain rated usage, that this is the maximum and will not be the actual usage all of the time.
Useful for those wanting to be as energy conscious as possible when choosing their devices.
Good video, however should have clarified that it's AC voltage you are measuring from the wall to the AC/DC power adapter brick, then DC voltage from the AC/DC power adapter brick to the connector that plugs into the back of your laptop. Set your multimeter accordingly.
Worthwhile noting that the multimeter has two voltage settings like the one in the video, you need to use the wave icon for AC (mains) and the line with dashed line underneath for DC (after the brick). Be careful checking mains and make sure you don't accidentally touch the prongs or touch them to each other!
Your welcome, glad it helped you solve your issue.
Dear Britec09
I thank you for your help, as I am just really getting into computer repair. I am an old electronics tech. A comment as a viewer. When setting up a multimeter it would help if you would also point out that you are turning it to AC volts or DC volts and explain when you should do each. Also when you have negative and positive volts you should not move the black lead just go to the negative post and your meter will show it as a negative volt. Thanks again for your help.
Thank you for nice answer, just trying to help make everyones experience as good as I received from your video. Keep up the good work. You are doing a great service sharing with the rest of us "flawed humanbeings". Thanks again.
@Britec09 el-cheapo is fine for normal computer tech work like that!
Thanks for making and sharing this video! You saved me from having to buy a new adapter.
@jmitservices Yeah that's a El Cheapo Multimeter, I have a fluke model which is real good.
Does it matter what leads you plug into the multi metre I see they have 3 holes to plug in and some of these metres show the red in the top hole and the black in the bottom with the middle hole free, they are the same metre like yours, M-380B but use different combinations with where the leads are plugged in. Does it matter?
Nice Video, be careful when testing mains with multimeters, make sure it's set for AC Volts and NEVER Amps. Also watch your fingers with those probes when they are measuring mains!
Thank you thank you thank you for making this video - now all I have to do is obtain a multimeter to test whether the problem lies in the adapter...
Nice tutorial brian.
Ive found the output cable often breaks close to the plug or powersupply end, plug end is easy to replace but the psu i end up carefully cutting round the lid seam with a hobby tool and mini grinding disk to gain access.
And after the cable is done then using epoxy resin to seal it back up.
Yes i am a tight sod :-)
Good video, wish you could have shown how to test the amps. If the voltage reads fine but the amps are lower than the stated amount, the adapter could still fail to power the device.
spot on advice. Helped more than you know!
Cheers.
Good video - clear, concise yet comprehensive.
@mitchman5155 yeah it was the c920
Great video.The right badly needed information.Thanks a mill!!
Thanks, glad you liked it.
Excellent! Thank you! This helped me a lot. Cheers!
Thanks. Very informative. How about if there is no pin inside the end connector/ barrel? ie it is just a barrel. Would just inserting the red probe inside it work?
Excellent and informative video. Answered all my questions. Many thanks.
As always a clear, lucid and informative video. Thx Brian.
Thanks for the strategies you have discussed here.
question about these blocks. I have a bunch of them at my house that are 19.5 v. About 15 of them. They all seem to work well. The amps listed are in the 6 amp range. I'm working on a project that I need to use one to get about 5 amps out of it. When I test the tip with a multimeter I get 19.6 v but I only seem to be able to get 1.6 amps out of each. Thank you for any advise you can offer.
Very clear for an electric dummy. That's me.
My grandson bought a model tank in Singapore last week and the first time he tried to charge it here in Thailand, he couldn't. Can't take it back to the shop obviously so took it to and electrical repairer. The original charger is input 220v output 9.6 V 250ma. The shopsold us an adjustable charger which goes from 1.5v to 12v and 500ma max. The electrician told us to set the charger to 12volts? By your video this is suicide. It charged once and OK. now it doesn't. Any comments please. The new charger is crap and the adjuster buttons have fallen out already.
+ron martin Mhg In Thailand they use very cheap materials and this sounds like a defect cord inside the charger. Don't use it and contact a repairer. These problems are common from Thailand electric toys.
Thank you for explaining properly and for Americans
You probably have the settings on the multimeter wrong when testing the volts. When you're testing the AC voltage you want to have it set on a v with a small ~ over it. When testing the DC voltage, it should be a v with two lines over it. One solid and the other dotted.
Good video - clear, concise and comprehensive.
Please warn the users to be extremely careful while checking AC supply, a shock from an inadvertent touch at 240 volts can range from traumatizing to fatal. Sometimes the end connector is damaged and has exposed wires and bending by touching directly can lead to shock.
Excellent video, thank you!
Shocking video Brian shocking :) Very good video mate! Could you show a video about how to test for amps? Thanks.
This removes the guesswork. Thank you!
very clear and concise video Brian !!!. good job
Hi Brian, it's a very helpful video, but do you think that it's wise to suggest people measure the 240v directly from the mains.. If set the multimeter up wrong or cross the probes, it could be toaster in the bath time.. thanks for the video though..
YOU GOT A NEW CAMERA!!!!!!!!!!!!!!!!!!!
Thank you! Very clear and concise. Helped me out tons. Cheers!
Nice Video Brian.. Keep them coming....
thanks! it was useful to test my faulty laptop charger!
Thanks mate, this saved me some money, much appreciated.
nice video :).
Question: If there were something wrong with the power brick & it happened to be outputting more than 20v & you tested it with the multimeter set to 20v (like in the video), could you potential destroy the multimeter ?
Very helpful for this newbee - much thanks
Nice video Brian. Did you use the C920? Looks very good..
Thank you for the clear explanation. Very good.
Huge help, appreciate the detail and clear instructions. So easy even an American can do it ;)
I checked my laptop charger with multimeter it stays to 19.67 v for 1 sec and goes to 1 after and stayed there any suggestions
hi did you turn it on at the wall before you tested the power cable
what about if the adapter has 3 holes instead of 2 [3-probe]? Is the upper one hole for earth?
Thank you! and also thanks
for commenting for United States differences
thank you so much for your explanation! it was very informative and clear.
Cheers mate.
@smallpebble7 Thanks mate
great video
Good video! A good multimeter is a must have!!
Hello, I have a Dell Laptop charger, where exactly is the +ve pin located? I've put the +ve probe on the center pin inside the jack and the -ve probe on the outer part of the jack, i'm getting no reading on the multimeter. when i place the +ve on the inside part on the jack, not the center pin I am getting a reading. please help.
Awesome video. Just the answers I needed.
brilliant tutorial, thanks, nice and clear...
Thank you! This was just what I needed to get me started. I was able to diagnose the issue and fix it. Can I call myself an electrician now? :)
Dankje deze video heeft mijn vragen beantwoordt.
Hi, maybe you can help me with this question. I have a several ac adapters from several different devices I've had in the past and also from things I've got recently. I have tested them with two different multi-meters and some of them read out differently than what is posted on the box that plugs into the wall outlet. The device voltage that they are powering is supposed to be whats indicated on the ac adapter box and the devices function normally. Is it possible that the multi meters aren't reading the voltage correctly? The multi meters read the same voltage. Example: ac adapter box says 14v output both multi meters read 21v. I was building a circuit on a breadboard and was using the voltage that the multi meter read to figure out my resister values, the circuit seemed to function as if the voltage on the ac adapter box was correct. Does that make sense?
Thanks man!
Great video! I learned a lot from u. Thank u very much! I see u just touch the pin while u are measuring. How come u don't get electrocuted? At minute 5:22 in video. If u touch the pins...or it looks like u are touching it but in fact u are not?!
Mr Mo that voltage is low enough that you don't even feel that. Current flows always on the less resistant part. In that case, the cable.
Hi, this video was very helpful, thank you very much and keep up with the good work. cheers
you explained so well.. thanks
Your welcome.
How to confirm the power of the "clone" adapter? I mean how to check the current (the video explain how to measure voltage)?
Similar question. If the charger wasn't working then the charge would be 0 volts?? I'm getting that on my charger.
Hey Brian very informative video thanks very much!
I Also enjoyed listening to you on podnutz :)
Thanks very much. This helped a great deal.
thanks, it was very useful and solving problem
The volts from the wall is fine, but when I test the plug after the brick, it gives a voltage reading that jumps all over the place, from 18v to 40v and in between. My adapter is rated for 18.5v. Also it won't charge my laptop anymore and forced a shutdown which prompted me testing it.
lol I'm guessing you have an auto-ranging multimeter. I'm guessing as it jumps all over the place from 18v to 40v that somewhere on the displays it reads mV (as in millivolts). So, you are really not jumping around between 18v to 40v but rather 18mV to 40mV, which means your brick has gone bad!
nice video..just want to ask..if want to double check the amp is correctly with spec in adapator..how?
This was so useful. Thanks a bunch!
Can you make a video on how to test Apple macbook charger
thanks for the vid. Can you explain the difference between the AC setting that has ~ and the one that you use to test the lower voltage? I thought ~ represents AC and the line with dotted line underneath represents DC. I see that it does not, since you used it to test the output volts. Thanks.
The tilde ~ setting does represent AC volts and the dotted line --- does represent DC volts. Why do you say that the dotted line does not represent DC volts? What he didn't tell you is that the output 19.5v is actually a DC voltage and the multimeter should be set accordingly for reading DC voltage. The part before the brick is in AC volts and the meter setting should be set to measure AC volts. In essence, the brick converts 240 AC volts down to 19.5 DC volts. He really should have mentioned this!!!
great work!
I tried my router adapter,that is a WAG200g with a 12V-1A adapter,and got a reading of "1" in the scale of 20 V DC.Then upped the scale to 200 and it showed me 207-210.But 207 what?!?I did a second reading in another adapter of the same output and got about the same results and always 1 in the 20 volts scale.I watched the whole video and followed your instructions to the letter,what the hell am I doing wrong?In fact I know the adapters are ok,I did it just to learn the multimeter.
Any thoughts?
240V standard, the absolute madmen
Thanks for the lesson!!
Thanks Rob, but i am just a common guy with a london accent
very good explanation!... thank you.
Great thanks
thanx a lot
Thanks for your help!
When check the DC Voltage in Adapter it is showing DC voltage below -14..
So does that mean my adapter is not working as the laptop is not getting charged the output given in adapter is -19.5 DC Voltage.....Please help.....(Thank u for the video too)Very informative.. :)
My battery output is 19v but my reading is giving me 21v, and my laptop is burn on the connetor side, would that be the reason?
This guys voice is awesome
What about the power adapters that need load to output proper voltage?
Nice and clear. Thanks!
Hi, how to test the output current (A) in a power adapter?
Very good, thanks.
How do you check the wattage? I have two Lenovo adapters both 20V one is 65W the other 90W. Thanks!
Multiply your amperage rating by voltage.
Thank you!
Thanks alot that video was very helpfull!
Everything checks out ok on my electrical adaptor, so why doesn't my laptop power up or charge the battery?
It is more than likely your battery needs to be replaced.
I found out what the problem was. The power adapter that came with the computer (that was given to me for free) didn't have enough amps. (The volts were correct though.) The battery is fine and I bought an after market a/c adapter and I'm back in business.