Desoldering thru-hole PCB components

Discussion in 'The Workbench' started by Kutt, May 30, 2020.

  1. Kutt

    Kutt Well-Known Member Gold Supporting Member

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    I've got a pedal with a broken on/on mini switch. I'm pretty good at soldering pots and jacks on guitars and did a bit of reading on similar work on PCB components. I have a long way to go.

    Took at stab at this tonight knowing full well I may fail and render the part inoperable but I learn by doing, and by failure.

    My solder sucker was too bulky for solder removal in this instance and the solder wick I have just won't pick up enough in such small areas.

    That said, are there other options for removing small solder areas like this on small PCB components? Even if I can get this switch off I am guessing I toasted the board. I'm OK with that, I jumped into it as a learning experience and would still like to get the switch desoldered and the new one installed.

    upload_2020-5-30_19-13-27.png
     
  2. Micky

    Micky Well-Known Member VIP Member

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    Hot air tool and a precision pry bar.
     
  3. ampmadscientist

    ampmadscientist Well-Known Member

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    It's a somewhat skilled job that requires professional soldering equipment.
    If you had the skill and the equipment the switch would be out, with no damage, in 5 minutes.
     
  4. thetragichero

    thetragichero Well-Known Member

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    i use copper braid, flux, patience, and restraint
     
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  5. Gutch220

    Gutch220 Well-Known Member

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    did you use the wick properly by putting it between the iron & solder? Not heating it up then quickly rubbing the braid on it before it cools.
    look into buying one of those wide soldering iron tips that can heat up multiple lugs at once.

    [​IMG]

    if you really don't care, cut the lugs and remove them individually rendering the component finished

    Speaking of which, if somebody wants to send me a link for one of those 'wide' solder tips used for a 'Weller WLC100 Solder station' please send it to me.
     
    Last edited: May 30, 2020
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  6. Kutt

    Kutt Well-Known Member Gold Supporting Member

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    I did indeed put the wick between the iron and the contact point. But it's not picking up the tiniest but of solder that's left behind. I don't have any flux. I think if I did it might have sucked it up. I have no issue destroying the switch to get it off, it's already junk. But there is precious little space on the other side of my pic between the base of it and the PCB.

    Is the consensus that the board is probably toast based on the discoloration and whatnot?
     
  7. South Park

    South Park Well-Known Member

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    Put a small screw driver between the part and the board like a wedge and heat things up the pressure will pull out the ends . Good luck
     
  8. thetragichero

    thetragichero Well-Known Member

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    board isn't toast
    get some flux and slather some on the braid
    clean up the excess flux once you're done with alcohol
     
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  9. ampmadscientist

    ampmadscientist Well-Known Member

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    The reason is:
    Not enough heat wrong temperature. Must use professional temperature controlled soldering station.
    Solder wick is oxidized not clean shiny copper.
    Flux is missing. MUST have proper electronic flux.
    If you are not using the proper equipment, no wonder it doesn't work.
    This is not an option. Get the right materials and do the job right.

    A 35 watt soldering iron is a joke. Get a real soldering rig.

    This won't work, don't even bother. I would use at least 85 watt soldering station.

    The wrong way:
    [​IMG]

    The right way:

    [​IMG]

    But besides this, you need skills to use it.
     
    Last edited: May 30, 2020
  10. thetragichero

    thetragichero Well-Known Member

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    ahhh see 35w is plenty for me for anything besides soldering to something large and metal, which i then bust out the 100w gun
    this weller modular 35w was life changing
     
  11. ampmadscientist

    ampmadscientist Well-Known Member

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    You won't unsolder this with 35 watts, sorry.

    [​IMG]
     
  12. dragonvalve

    dragonvalve Well-Known Member

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    TO have the better tool you'd need this...

     
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  13. Matthews Guitars

    Matthews Guitars Well-Known Member

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    Desoldering is easy with: Bigger solder wick, flux, and an iron with more than adequate thermal capacity, with a tip that's the right size. (Which is as large as is practical without desoldering the next connection over at the same time.)

    The wick should be as wide as, or wider than, the solder pad to be desoldered. Use fresh product. The copper should be clean and shiny. Tarnished wick is trash.
     
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  14. Kutt

    Kutt Well-Known Member Gold Supporting Member

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    Thank you for answering my questions directly and replying with useful facts.

    As I basically stated I set out to learn with this little project. I was not expecting pristine results on the first try as others may have interpreted.
     
  15. thetragichero

    thetragichero Well-Known Member

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    you'd be horrified to see my first monkeying around in an amp. always was more of a hands on leaner, at the expense of some working equipment. i wouldn't suggest going that route but there are certainly worse things that you could be doing
     
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  16. ampmadscientist

    ampmadscientist Well-Known Member

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    Soldering takes lots of practice.

    A person who picks up a soldering iron cannot expect professional results without the education.
     
  17. thetragichero

    thetragichero Well-Known Member

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    great way to learn is with old broken electronics. practice on stuff you don't care about frying
     
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  18. Kutt

    Kutt Well-Known Member Gold Supporting Member

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    Funny you mention that. I have a spent carbon monoxide detector that I first disassembled and desoldered some parts from. My pedal is being a bit more feisty, however.
     
  19. Gene Ballzz

    Gene Ballzz Well-Known Member

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    Proper care, feeding, preparation and maintenance of the tip is critical to all soldering operations. Although some folks may have personal specifics they prefer, here is a good general guide. While a long read and seemingly complicated, once it becomes habit, its quite simple in practice.

    "First, whenever soldering to the back of a pot that has never seen solder before, it really helps to either scrape, file or sand a portion of the surface to get to "clean" metal, as there may be oils, glaze, release agents and/or other contaminants or finish on the metal to reduce corrosion or aid the manufacturing process. Cleaning this area "before" applying solder will enhance the heat transfer of your iron AND the adhesion of some fresh solder.

    Next, read, digest and follow my verbose suggestions below and amaze/impress your friends with the quality of your new soldering skills!


    Proper care, etiquette and maintenance are as important, if not more so, than the iron itself!

    A) Get a soldering iron/station that has the option of various tip sizes, along with a small assortment (2-4) of sizes of tips. Use the smaller for "fine" work and the larger for heavy stuff, like the back of pots, larger audio speaker connectors, etc. Right tool for the job. A stand is also good to have, if you don't get a station with one built in.
    B) Get a small sponge. The ones made specifically for soldering iron use are best and keep it damp to wet while soldering. Clean it by running under water and squeezing it out a few times before each soldering session. And, oh yeah, have a trash can handy!
    C) Before first use, heat iron up and wipe it on the sponge, then liberally apply solder to the tip and shake the excess off into the trash can. I call it the rattlesnake shake! Wipe tip off on the sponge and reapply solder. The iron is now ready to either be turned off/stored or sit there heated up and ready for use. "NEVER" let a soldering iron sit, while on or in storage without having had a fresh cleaning and coating of solder! The coating protects and seals the tip from oxidation and that oxidation (as well as a dirty tip) is the enemy of good, efficient heat transfer.
    D) Now that your iron is heated, prepped and sitting happily in it's stand, get you wires/work arranged the way you want them. Pull the iron from it's stand and do the rattlesnake shake into the trash can, wipe tip on sponge, and dab a touch of solder onto the part of the tip that you want to use, apply that tip to the joint and then apply solder to the joint.
    E) When a suitable amount of solder has flowed into the joint, pull the solder away and then pull the iron away, "WITHOUT" disturbing or jostling the wires.
    F) If more joints need to be soldered, repeat "D" & "E". If done or more prep is needed for the next joint, do step "C"!
    G) When you're done, do step "C" and store your iron/station, ready for it's next adventure.
    H) FWIW, each wire should get "pre-tinned" before use. This is simply heating the wire enough to apply a bit of solder and then shaking off the excess. If ya can't shake it (not enough length or room to do so), just a little dab of solder will do.
    I realize this sounds like a lot of details, but religious adherence to these steps will get you well on your way to successful soldering that you can be proud of, as well as good longevity of your soldering iron! Once you develop it as a "HABIT" it's not as complicated as it sounds, though the details and sequence of events is fairly important!

    Oh yeah, a couple more points. Once your tip no longer likes to accept solder and provide (when wiped) a nice shiny coating, has a lot of black deposits on the working surface or becomes heavily oxidized, its time to replace it. And most tips won't give much satisfaction from "sanding" to a fresh surface, especially the more "high-tech" temperature sensing/controlled units!"

    This is the one I've been using almost daily for over 10 years, for multiple repairs and amplifier builds, and a wide variety of tips are easily available:

    https://www.amazon.com/Weller-WES51...9143216&sr=8-2&keywords=weller+soldering+iron


    This one saves a few bucks, but is just "so-so" and if you think you will use it more than a couple times a year, bite the bullet and get a good one:

    https://www.amazon.com/Weller-WLC10...9143216&sr=8-1&keywords=weller+soldering+iron

    And while free standing "pencil on a cord" units can be handy for a "quick, mobile" toolbox, they just don't have the quality to make them a good value.


    Just My $.02 & Likely Worth Even Less!
    Gene
     
    Last edited: Jun 2, 2020
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  20. tmingle

    tmingle Well-Known Member

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    You can try re-soldering the pads then reheat one at a time & gently tap the board on your bench. It has worked for me in the past. I also use Solderwick.
    The newer stuff with ROHS solder can be a genuine pain in the ass to remove though.
     
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