What's this growing on the solder joint?

Discussion in 'General Electronics Chat' started by Stringybark B, Mar 18, 2016.

  1. Stringybark B

    Thread Starter New Member

    Jul 22, 2015
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    0
    Hey all,
    I opened my 7 year old remote presenter pointer to figure out why it's suddenly stopped working.
    Could this stuff that's growing on the solder connecting the battery spring to the board be causing the current not to supply to the circuit?
    If so, can I fix this by reheating the solder, removing it and adding new? Or is it a waste of time?

    Photo attached. 20160318_191839-1.jpg
     
  2. #12

    Expert

    Nov 30, 2010
    16,345
    6,831
    Clean the wad off and see how much damage happened.
     
  3. Stringybark B

    Thread Starter New Member

    Jul 22, 2015
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    Cleaned up version: cleaned.jpg
     
  4. Kermit2

    AAC Fanatic!

    Feb 5, 2010
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    951
    It's the electrolyte which leaked from the battery.

    Very corrosive stuff. Soft toothbrush, isopropyl and plenty of gentle scrubbing will get it clean.

    Use an ohm meter and verify continuity across corroded traces. Use jumper wires and solder to reconnect components if a trace is open.

    Finally, some advice you probably know now. Don't leave the battery in it when stored away.
     
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  5. #12

    Expert

    Nov 30, 2010
    16,345
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    Is that copper trace open by the letter A or has it survived because it has both the green coating and a white line protecting that little bit of copper?
    You're going to have to get in there with a 10X jewelers loupe to see if the corrosion ate the end off that yellow capacitor.
    Maybe the light green line (on the other side of the solder blob) on the battery holder got dissolved.
     
  6. Wendy

    Moderator

    Mar 24, 2008
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    The capacitor appears to be a 47uf 10V.
     
  7. Stringybark B

    Thread Starter New Member

    Jul 22, 2015
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    That copper trace sure looks open, not just in the photo but under the magnifying glass as well.
    The capacitor kind of looks OK after I cleaned up around it some more. But that copper trace is definitely open.
    The photo is reasonably clear, I think.
    capacitor.jpg
     
  8. Stringybark B

    Thread Starter New Member

    Jul 22, 2015
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    Seems to be a 'lets bin it' situation, right?
     
  9. dl324

    Distinguished Member

    Mar 30, 2015
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    You can use wire to bridge the open.
     
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  10. Dodgydave

    AAC Fanatic!

    Jun 22, 2012
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    You can rework the copper track with solder and wire strands.
     
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  11. wayneh

    Expert

    Sep 9, 2010
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    3,061
    I agree with the assessments of the problem, and that it can possibly be repaired with some effort. If you have the tools and skill to do it, it may be worth your effort. (Success may hinge on whether that capacitor is disconnected/destroyed or not.) If you have neither the tools nor the skills, it's unlikely to be worth it.
     
    Last edited: Mar 18, 2016
  12. Picbuster

    Member

    Dec 2, 2013
    376
    50
    Small advice: Always coat pcb's. Use conformal coat this will protect yr PCB and components.
    I use HPA )1ls. operational from -60 to 130 degree centigrade. See http://www.electrolube.com/
     
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  13. Stringybark B

    Thread Starter New Member

    Jul 22, 2015
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    I'll give it a try. Won't take too long and I might get it to work. If not, well, I will have learnt something.
     
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