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Soldering issue with car keycard repair!

Discussion in 'Troubleshooting and Repair' started by maclean, Dec 19, 2012.

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  1. maclean

    maclean

    7
    0
    Jul 25, 2012
    Hi everyone,

    The keycard for my mothers car is supposed to allow her to start her engine when she puts the card in the slot... Well the other day it didn't work and continued to display 'insert keycard' and engine wouldn't start!

    So upon reading up I discovered its an extremely common fault due to bad design of the keycard, and can be easily repaired by opening the card and soldering a joint.


    So I opened the card and as expected a point was loose, so i soldered it on and it was working fine again :)...

    The problem is however that the connection is extremely weak and is not holding up to even the most gentle of stress and therefore is breaking after 2 or 3 uses and leaving my mother stranded at the most awkward of times.


    I have done my fair share of soldering, however only with standard components that go through the board...

    This seems to be some kind of surface mount device and I have not had to work with these before.

    Should I be using some kind of special solder for this task? I have attached two photos and the point in question is the left most of the three points coming from the large black circular device towards the bottom.

    Its not till taking these photos and blowing it up on screen that I can see it does actually look quite messy there as I have re-soldered it about 4 or 5 times now. however i am wondering if some kind of pad has come off and this needs glue rather than solder or something?

    From reading the car makers forums taking this to a dealer will result in them charging over £150 for a new card, which I begrudge given I know this is all the problem is...

    Any one got any ideas on what i can try here? Many thanks for any pointers!!



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    Last edited: Dec 19, 2012
  2. CocaCola

    CocaCola

    3,635
    5
    Apr 7, 2012
    Post a picture of the other complete other side of the board (like your first picture), also the top right leg looks to be a bad solder joint as well and needs to be touched up...
     
  3. maclean

    maclean

    7
    0
    Jul 25, 2012
    Thanks for your response! I will try touching the top right one up again then, maybe it is contributing to the intermittence of this fault!

    Here's a shot of the back of the board, thanks for looking!!

    [​IMG]
     
  4. CocaCola

    CocaCola

    3,635
    5
    Apr 7, 2012
    The solder joint you have been touching up (left) appears to be nothing more then an anchor point aka no connection to anything... Take some isopropyl alcohol (or acetone, just use caution around the plastic parts with acetone) and remove all that flux residue, than take a blob of two part epoxy and secure that tab back to the PC board (other glues will work but I highly recommend two part epoxy for this application), then resolder the joint I suggested on the right, heck solder both of the joints on the right just to be sure...
     
  5. maclean

    maclean

    7
    0
    Jul 25, 2012
    Thanks very much, so the reality is that is actually likely the top right joint that is faulty but the fact the anchor point floating around is not helping things at all.

    You have given me enough info here to go and try this all out so thanks a lot, I suspected some kind of glue would be needed as there is nothing left for the solder to fuse to, but had no idea what to use!

    The only thing im not sure about is heck solder? I did a quick google and get alot of ben heck videos? But I am not quite sure what heck soldering is?
     
  6. CocaCola

    CocaCola

    3,635
    5
    Apr 7, 2012
    US slang "heck" equates to "why not just"
     
  7. maclean

    maclean

    7
    0
    Jul 25, 2012
    totally misread that lolol I see now..

    Thanks for your help!
     
  8. Raven Luni

    Raven Luni

    798
    8
    Oct 15, 2011
    The approach I always take with things like that is to bypass the joint - take a small wire from the component pin to the next solder joint on the track.
     
  9. CocaCola

    CocaCola

    3,635
    5
    Apr 7, 2012
    In this case the 'lifted' pad appears to simply be a mounting point not a connection so no jumper wire needed, thus my recommendation to simply glue it down... As for the bad soldered leg, it looks like just a bad solder and the pad appears to be fine, but yes if the pad is broken a jumper wire would be a possible solution... Although in this case I would probably just bend that leg a little more toward the nearest cap is connects to and bridge with some solder...
     
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