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Cannot remove caps from motherboard

Discussion in 'Electronic Basics' started by Anonymous, Sep 23, 2012.

  1. Anonymous

    Anonymous Guest

    I'm trying to repair my MSI motherboard by replacing the caps near the
    regulators since they are bulging and are most likely defective.
    However, even at the highest setting of my soldering iron (480 degrees
    Celcius) I'm unable to liquify the solder. I don't know what kind of
    solder they're using for motherboards but it's obviously not the kind
    you can easily manipulate with common DIY tools.

    Anyone have a trick for solving this problem?
     
  2. Jamie

    Jamie Guest

    feed low temp solder into the junction, it'll soften and mix with it.

    or, could it be possible your iron is not properly functioning?

    also, by using a blunt tip like a spade tip, it makes the job easier
    to heat the area. With small tips you don't have a lot of heat retention.

    Jamie
     
  3. Tom Biasi

    Tom Biasi Guest

    Keep in mind they are multilayer boards.
    Removing parts can be tricky or even damage the intermediate layers.
    Dell had a problem with caps a few years back and replacement turned out
    to be not nice.

    Tom
     
  4. Guest

    If it were really 480C, you'd have destroyed the board. Even RoHS solder
    melts before 350C. Your iron probably doesn't put out enough heat (wattage
    too low) or is defective. These caps are tied directly to internal planes so
    it can take a *lot* of heat.
    As Jamie suggested, you can try melting in some 63/37 solder to lower the
    melting point of the solder that's already there. You gotta get the solder
    melted before any other techniques will help, though.
     
  5. Phil Allison

    Phil Allison Guest

    "Anonymous"
    ** Wiggle the caps until they break away from the PCB leaving only the stubs
    of the leads in the PCB.

    Then you can heat the stubs directly and remove them.

    OR, just solder the new caps to them, keeping the leads short.



    ..... Phil
     
  6. Rich Webb

    Rich Webb Guest

    Might try lowering the melting point with some of ChipQuik. It is
    marketed as an aid for surface-mount removal but I'd guess that the
    lower melting point might be helpful here as well. Fairly inexpensive,
    so it's a handy tool in your kit, regardless. http://www.chipquik.com/

    Note: yes, it's kind of a hokey website but the stuff really does work.
     
  7. fungus

    fungus Guest

    Get a big pair of pliers and pull very hard!

    With a bit of luck you'll leave the legs behind
    and you can solder the new cap onto them.

    Failing that, add some more solder. This gives
    a better thermal contact with the soldering iron.
     
  8. Anna Joshi

    Anna Joshi Guest

    The Do's & Don'ts of an Engineering student.




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  9. fungus

    fungus Guest

    Whoosh.
     
  10. sadly I agree with this.

    even with a real iron, it's a serious PITA to remove those things.
     
  11. Phil Allison

    Phil Allison Guest

    "Cydrome Leader"

    ** Lotsa folks don't think of the easy way to do things - like cutting ALL
    the pins on an IC or transistor THEN removing each one individually. This
    is waaaay easier than trying to perfectly desolder all the pins at once,
    particularly with plated through holes.

    If you do not have vacuum de-soldering gear, it is the only sensible way to
    get most parts off a PCB.


    ..... Phil
     
  12. BeeJ

    BeeJ Guest

    Trick?

    Cut the cap off at the board level. Use a razor saw if needed or just
    a good quality side cutter.
    This will reduce the heat mass your biggest enemy.

    Make sure your tip is screwed on properly and you used the proper
    "lube" on the the threads (if that is the kind) and make sure it is
    very tight (tip to iron). Any small amount of disconnect is high
    resistance to heat flow.

    Use a broader tip since this will increase heat flow to where you need
    it. Use a tip with a width close to the pad width. Pointy tips are
    not for this kind of work.

    Use your solder to to help transfer the heat to the joint and to lower
    the melting point of the existing solder.

    Use a toothpick to carefully eject the lead. Do not twist the
    toothpick as this can lift the pad.

    Good luck.

    My tech only used the desoldering tool to clean out empty pads never to
    remove components. Aerospace trained. He never lifted a pad in ten
    years of working for me.
     
  13. Ross Herbert

    Ross Herbert Guest

    On Sun, 23 Sep 2012 19:37:35 +0000 (UTC), Anonymous

    :I'm trying to repair my MSI motherboard by replacing the caps near the
    :regulators since they are bulging and are most likely defective.
    :However, even at the highest setting of my soldering iron (480 degrees
    :Celcius) I'm unable to liquify the solder. I don't know what kind of
    :solder they're using for motherboards but it's obviously not the kind
    :you can easily manipulate with common DIY tools.
    :
    :Anyone have a trick for solving this problem?

    I tend to agree with Michael Terrell.

    Unless you use at least a 45W iron you won't get enough heat into the joint to
    remove the solder with conventional solder suckers or wick. Because there is no
    way to get a razor saw (as someone suggested) in the space available on a MB it
    is impossible to cut the leads this way. In most cases you can't cut the leads
    with side cutters either, even using fine bladed types, due to lack of
    clearance, so this is not an option either. One method I use quite successfully
    is to keep the soldering iron tip on the underside of each pin in turn while
    putting slight pressure on the same side of the upright electro. You can usually
    rock the pin out by a fraction of a mm each time and after several side-to-side
    rocks, heating each pin in turn, you can get both pins free. You must be careful
    not to apply too much side pressure otherwise you risk stripping the thru-hole
    plating. Afterwards it is a simple matter to use new solder (and/or liquid flux)
    to complete the cleanout of each thru-hole with a sucker or braid.
     
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