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Power Jack Issue — Parallax Forums

Power Jack Issue

MechelecMechelec Posts: 7
edited 2005-04-14 17:51 in General Discussion
Hello,

I put together a circuit on a PCB, and one of my elements is a 3 pin power jack.· When I plug in my supply, the power LED does not turn on, but, through trial and error, it will turn on when I put my finger on the metal surface of the back of the jack (I think it's part of the neg terminal but it could be GND).· My circuit is valid and I'm using the appropriate supply, and I've been tinkering with the jack's soldering but I can't fix it.· It would make sense if the part I'm touching is the GND term, and it is only properly grounded to my body, but it's more likely this terminal is the negative one.· So anyone got a clue whats going on?

Comments

  • OrionOrion Posts: 236
    edited 2005-04-14 11:07
    I doubt your finger is completing the ground. Skin is not a very good conductor and only a fraction of a ma would flow at 5v. Not to mention you would feel it! Most likely something is broke in the connector and the pressure from your finger is connecting something in it. Check it with a voltmeter and see what is going on.
  • ForrestForrest Posts: 1,341
    edited 2005-04-14 11:26
    You may have accidently bent the jack's metal tab that makes contact with the tip of the power jack while soldering/mounting the jack. Try bending the metal tab. Also - make sure the jack is free of flux by cleaning it with a Q-tip and alcohol.
  • StarManStarMan Posts: 306
    edited 2005-04-14 15:39
    I have a number of 2.1mm power jacks with 3 tabs.· One tab is postive, one tab is ground, the third tab has continuity with the ground tab but disconnects when the plug is inserted.· I have made the mistake of using the disconnecting tab.



    Chris Isaacson
  • MechelecMechelec Posts: 7
    edited 2005-04-14 17:51
    Upon further investigation, the power flickers when I jiggle the supply line. The jackhead isnt permanently connected to the supply line, it can be detached so you can use different jackheads. So now I'm thinking I have a poorly built supply, though that still doesn't explain why my finger on the back of the female jack makes it work (and only my right index too!). There's a little flux on the soldering, but not enough to make it a bad joint. I cleaned it with alcohol as best as I could but it didn't help
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