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laptop DC power jack - burnt solder joint

Discussion in 'Do It Yourself (Not Computer-Related)' started by nettxzl, Mar 10, 2006.

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  1. nettxzl

    nettxzl Thread Starter

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    Hi,

    One of the solder joints connecting the DC power jack to the mainboard on my notebook (Acer Travelmate 345T) has broken (burnt). I'd like to try to repair it myself but I'm not sure how to remove the old solder and to clean the connecting pin and the copper pad.The parts are so small it's difficult to see how to handle them without damaging something else. I've attached a jpg file showing the burnt solder joint (cyan arrow points to it). I'd very much appreciate any advice how to clean off the old solder without damaging the copper pad under it (I'm assuming that's what the brown oval surrounding the pin is). Also, I'm not sure what the connecting pin is connecting to. Assuming I manage to clean off the old solder, would it be enough just to solder the connecting pin to the copper pad? Or is there a connection to some trace I should also be checking?

    Apologies for my cluelessness. I really haven't any experience with this. If I were living in the US/UK I'd send it in to one of the innumerable places I've found with Google that specialises in this type of repair. Unfortunately, I haven't found any equivalent place nearby.

    TIA
    Toni
     

    Attached Files:

  2. wacor

    wacor Banned

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    This may sound crazy but if there is a watch repair or jewely store then they might have some delicate soldiering tools.

    sometimes you can just heat it up and not have to clean up / remove the soldier. not the recommended way for electronics though.

    the concern i would have is what caused the overheating or was is what i call a cold joint that never was soldiered correctly to begin with.

    If you really are intent to make the repair yourself you would need to get a small soldiering gun. then you would heat up the existing connection until the soldier has liquified. at that point you would get a device that would suck it up. something like a small baster (for cooking) made for the purpose. once that is all done then you have to properly heat the connection again and resoldier.

    you might try doing a google search for more info on how to do it yourself
     
  3. gotrootdude

    gotrootdude

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    Radioshack sells a cheap desoldering iron with a squeeze bulb attached for around $15. While your there, pick up some desoldering braid, and the narrowest resin core solder you can find.

    Along with a second pair of hands, heat the existing solder on the contact pad with the desoldering iron and suck as much of the old solder up as possible. Use the desoldering braid to remove any stubborn solder.

    When you get ready to resolder the connection, melt a little solder directly onto the tip of the iron (if it starts to drip, you've got too much solder on the iron), then touch the iron to the contact pad and roll the tip of the iron around the pin, the solder should spread out evenly on the contact pad.

    Do not use globs of solder! If it doesn't look almost exactly like the other soldered connections, then suck the solder off and restart.

    Do not hold the iron to the pin. Use the iron to transfer the hot solder to the contact pad, it should spread out to hold the pin in place.
     
  4. wacor

    wacor Banned

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    I was going to mention Radio Shack but the comment "If I were living in the US/UK I'd send it in to one of the innumerable places I've found with Google that specialises in this type of repair." led me to believe there are not a lot of options available where he lives.

    one other thing is to make sure you buy the right soldier for electrical - you cant use just any soldier.
     
  5. nettxzl

    nettxzl Thread Starter

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    Thanks for the responses. Yes, I have done google searches on soldering etc and the info I've found is more or less in line with your suggestions, e.g. using a desoldering pump and desoldering braid. I'm just finding the small scale I have to work on daunting and I'm worried about damaging the PCB/traces/other components so I was wondering if there were any precautions/gotchas I should watch out for.

    Also, as rightly observed by wacorsaut there are a lack of options around here (no Radio Shacks), e.g., the smallest diameter solder I've been able to find is 1.2 mm, but all the info I've found with google suggests I should be using 0.6 mm or less. Still haven't been able to find any desoldering braid.

    Anyway, thanks for the help.

    Toni

    PS. The broken joint was caused by the stress of the power cable pulling on the jack. A google search (laptop power jack) reveals that this is a common problem with notebooks. In many cases it seems the jack is only soldered on to the mainboard but there's no strong mechanical connection holding it in place so the solder joint ends up taking all the mechanical stress. Eventually with much usage it breaks. There's a nice fix that someone came up with for a compaq notebook which I'd quite like to try but I haven't been able to remove the mainboard from the notebook's upper casing so I can only see the bottom of the board.
     
  6. Mitek

    Mitek

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    There is a company dedicated to laptop jack replacement. Expensive, but they do great work. We outsource all of the laptops with broken jacks to these guys and have for years.

    You can also get jacks there as well. Hardware there is cheap however just like in childbirth, its the labor that kills you ;)

    www.laptopjacks.com
     
  7. wacor

    wacor Banned

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    Somebody will probably chew me out for this idea but I have done it with some success with circuits. If there is soldier at the connection which it appears there is then you get a small soldiering gun and touch it to the connection until the soldier old melts and as soon as it does take away the gun and let it cool. To try to keep the heat from transfering on the part you are soldiering you hold onto the connection on the opposite side of the board.
     
  8. Mitek

    Mitek

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    I have done it as well BUT knowing how some people are I wouldnt make that suggestion :)

    Had a guy working for me a couple of years ago that was supposedly a soldering guru. I purchased a complete solder station and desoldering station (expensive to say the least) and he ended up costing me a fortune in laptop repairs
     
  9. Rollin' Rog

    Rollin' Rog

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    From the screenshot I'd say it should be a piece-of-cake to get a little solder on there with a fine point iron. I wouldn't desolder anything.

    But what in the heck caused it to burn out like that? You may have a short someplace.
     
  10. wacor

    wacor Banned

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    If that was a weak connection caused by stress i would have expected there would have been some tell tale signs before. I also question if a short in something caused this.
     
  11. nettxzl

    nettxzl Thread Starter

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    Yes, there were plenty of tell tale signs before. It started with the power cutting out occasionally and the notebook dropping back to battery power then recovering back to ac power by itself. Then the ac power cut outs got worse but if I jiggled the plug thing (don't know what you call it) going into the dc power jack I could get the ac power back again, but it got harder and harder to find just the right position for the plug. More and more jiggling (I know I shouldn't have jiggled it). It got to the point where you're hanging onto the plug pressing it into the dc jack with one hand and typing with the other. (The battery only lasts about ten minutes). And then one day smoke started coming out that corner and that was that.

    I'm in search of a fine point for the iron now. And thinner solder. Both the soldering iron and solder I've got so far look thicker/wider than the pin and copper pad.
     
  12. Rollin' Rog

    Rollin' Rog

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    RadioShack probably has what you want. I got cheap soldering iron (under 10 bucks) from them years ago, and bought a special fine point tip from them to go with it. The tip eventually broke after years of use -- but it would do the job.

    If you've never used a soldering iron before, there's a bit of technique to it: heat the tip up, then use a wire brush to clean it. Then apply solder to the tip to "tin" it.

    Once that is done, heat the part to be soldered for a few seconds then apply solder to the junction between the tip and the part.
     
  13. kiwiguy

    kiwiguy

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    I would express concern at the source of the heat that caused the joint to de-solder in the first place.

    I would stronlgly suspect that the jack itself is damaged (high resistance connection) that caused the heat in the first place.

    But a straight resolder would only take about 3 seconds on that joint.
     
  14. Guyzer

    Guyzer

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    A fine soldering pencil is what you need, not an iron or gun. Cheap like borscht, vorking like a charm if you follow the advice already given about using the braid.
     
  15. nettxzl

    nettxzl Thread Starter

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    Yes, I worried that the jack itself might be damaged so I checked the resistance between the pin in the centre of the socket in the dc jack where the plug goes in and the pin poking out of that burnt joint and it is close to zero ohms, at least so far as I can tell with an analog meter. So I'm hoping the jack is ok and the high resistance was due to the weakening/breaking solder joint. Fingers crossed.
     
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