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plastic base of mini switch melts when i try to solder...


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  • plastic base of mini switch melts when i try to solder...

    I am working on a re-wire project which involves a separate 3-way switch for each pickup. I purchased 3 mini switches for this application. T he probelm is that when I try to solder the wires to the posts, the surrounding plastic melts before the post even gets hot enough to take the solder. 35w and 65w 

    soldering irons, no difference.  


    the switches i am using are the same you will find with a search for '3-way dpdt mini switch'. ive seen red, blue, and black models, I am using the black ones.


    i know that soldering is a bit of an art and i am a begginner, so i accept that maybe it's just me. so are these switches meant for machine soldering?? maybe I have bad technique?? or are there better options for switches that will not when heating up the wire posts??

    ESP LTD MH-350FR (EMG 81/85) - PRS SE Custom 24 (GFS OW Liverpool / SD JB) - AXL Badwater SRO (G&B Vintage / SD Buckbucker / G&B HFS) - Mitchell MD-100SCE - Guitar Rig 5 Pro

  • #2

    Use a 15-25W iron for fine electronics work, with a sharp, pencil-like tip.

    Save the 35-60W for big switches, 1/4" plugs/jacks, ground wires to hardware and so on. (For automotive soldering, there are even 300W irons, ha!)

    Stay away from low-end Weller irons; they only make high-end soldering workstations that are any good. A ten dollar made-in-China 20 watter will beat a 50 dollar Weller in tip longevity.

    (The best thing, of course, is a temperature-regulated soldering station; regulation is much more accurate than controlling the temperature via wattage! If it's going to be unregulated though, the wattage has to be low.  Unregulated + high wattage = bad for small electronics.)

    Use a clip holder to hold things together so you can just solder quickly, and not have the parts move. If the parts don't move, it only takes a second or two to make a good joint.  These clip holders are cheap. I have one with two clips and a magnifying glass. I paid around $8 for it at a local electronics shop.

    The part being small works in you favor: it does not draw too much heat away from the joint so you can heat it quickly and be done.

    Also, if you're using lead-free solder, that will be a big cause of frustrations due to the higher melting point, poor flow, and poor visual appearance of joints (they lack shine, and so look cold when they are not).  40/60 tin-lead solder is what you want.

    Don't use excessively low gauge (thick) hookup wire. That is hard to solder to a switch with small terminals. Inside a guitar, you can use thin wires, like 24 gauge or thinner, up to 30 easily.

    If the switches still give you grief, consider mounting them on a small piece of PCB stripboard.  Then solder the other connections to matching connections on the board. This saves you from the grief of multiple wires converging on one pin, or joining "in the air" away from the part. There are various kinds of stripboards, like ones that take integrated circuits.  A DPTD switch which has 0.1" pin spacing may be able to fit right into one of these. For example: http://www.ebay.com/itm/PC-PCB-VERO-STRIP-BOARD-IC-PIC-91x45-20-pin-DIL-L99-/150447096307   Not long ago I worked with something exactly like this. I cut just a quarter of it; it was for mounting a power transistor (TO-220 package) with a heat sink and a couple of passive components. The circuit required no jumpers or point-to-point soldering whatsoever.

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    • WRGKMC
      WRGKMC commented
      Editing a comment

      Heat sink your connections so the heat passes into the heat sink, not down into the base of the switch. You can use alligator clips or better yet some forceps. Tightly clamp the forceps between the solder joint and the base of the switch. There isn't much room on small switches but I've always been able to do it.

      Next tin the wires you are going to connect before you place them through the loops and trim off excess - then heat the joint before you add solder. Bring the metal up to temp and the solder melts instantly when you apply it. Do not apply solder to a cold joint. Heat it first, then apply. A big glob of melted solder will surely overheat the connection and it takes too long to cool. You only need to get solder on where the two conductors meet and the solder flows and looks silver.