Author Topic: DC power jack shows voltage in 3rd pin when plugged in?  (Read 1821 times)

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Offline gerathegTopic starter

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DC power jack shows voltage in 3rd pin when plugged in?
« on: August 22, 2014, 07:26:40 pm »
I have a few DC power jacks of various sizes and shapes with 3 pins, 2 of them are connected when not plugged in, 1 is isolated for positive. When a plug is plugged into the jack usually the 2 that were connected disconnect, one goes to negative, the other - which I will call the third pin - isn't connected to anything. This is true for all power jacks and none of them show voltage in the third pin except for one.

That's strange, where is this voltage coming from to the third pin if the pin is disconnected? Is this something to worry about and should I get a new adapter?

This is a picture of the adapter that shows voltage, I only have one piece: 5.5mm x 2.5mm DC Power Jack
« Last Edit: August 22, 2014, 07:33:49 pm by geratheg »
 

Offline SeanB

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Re: DC power jack shows voltage in 3rd pin when plugged in?
« Reply #1 on: August 23, 2014, 05:43:16 am »
Likely leakage through the phenolic insulation.
 

Offline dr_dan

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Re: DC power jack shows voltage in 3rd pin when plugged in?
« Reply #2 on: August 23, 2014, 07:16:01 am »
The jack might be faulty - check for shorts between the two pins.
This third contact is only used to disconnect a battery when the supply plug is inserted. If you don't need that functionality, the jack will be fine as it is.
 


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