Author Topic: Finding the polarity of a barrel jack  (Read 806 times)

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Offline shobo

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Finding the polarity of a barrel jack
« on: April 06, 2018, 10:18:41 am »
hey all.
i have an old tablet with a barrel jack connector but the charger is missing.althogh i can find a charger on ebay,it's expensive - 5$ plus.i can buy a barrel jack for peanuts and cut an usb cable.

my issue is that i cant determine if the power jack should be center positive or not.

the tablet can be easily opened and i want to know if the polarity of the plug can be traced with a multimeter .

thanks in advance

Sent from my SHV-E250L using Tapatalk

 

Offline Ranayna

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Re: Finding the polarity of a barrel jack
« Reply #1 on: April 06, 2018, 10:41:54 am »
First, non-tech solution: Check the manual. Any decent device should have this stated there somewhere. That will also help you to confirm the required voltage, since in my experience barrel jacks for 5 volts are rare. Also name the device, maybe someone here knows the polarity.

Otherwise, open it up and check connectivity from the jack to any exposed shields. Those are generally at GND, so would be connected to the negative input.
EDIT: See the latest EEVBlog (IIRC #1071)  for example. At the beginning, Dave shows how he determined the polarity of the barrel connector.
« Last Edit: April 06, 2018, 10:44:18 am by Ranayna »
 
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Offline shobo

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Re: Finding the polarity of a barrel jack
« Reply #2 on: April 06, 2018, 10:46:13 am »
First, non-tech solution: Check the manual. Any decent device should have this stated there somewhere. That will also help you to confirm the required voltage, since in my experience barrel jacks for 5 volts are rare. Also name the device, maybe someone here knows the polarity.

Otherwise, open it up and check connectivity from the jack to any exposed shields. Those are generally at GND, so would be connected to the negative input.
EDIT: See the latest EEVBlog (IIRC #1071)  for example. At the beginning, Dave shows how he determined the polarity of the barrel connector.

Thanks!
 


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