This guide will show you how to properly tin wires for soldering to speakers, circuit boards, motors tabs, or any other solid surface. If you are splicing wires (soldering two wires together) a slightly different technique is required.
Please do not use any flux either liquid or paste on motherboards or decoders. Over time, the acidic properties of liquid or paste flux will begin eating away at the fiberglass PCB and will damage it. Use only Rosin-core solder or no-clean flux approved for electronics use.
TCS recommends the use of Kester "44" Sn63 Pb37, .015" diameter Rosin-core solder. Kester part number 24-6337-0007.
Step 1: Strip no more than ~1/32" of insulation from the end of the wire. This is critical for good results. Stripping more than 1/32" will lead to problems. Use only 30 or 32 gauge wire for decoder work. Be sure to use the 32 AWG hole on your wire stripper so you don't cut through the copper strands.
Step 2: Hang 1/2" of wire from the stripped end off the end of the workbench.
Get your soldering iron heating up to approximately 680F degrees. Make sure the tip of your soldering iron is clean and shiny. Use tip tinner and clean the tip often using a damp sponge or brass tip cleaner pad.
Step 3: Use your pinky finger to hold the wire on the table while bringing the solder and soldering iron together on the stripped end of the wire. All 3 items should make contact at once and shouldn't need to be in contact for more than 1 second. If you don't get good coverage on the first pass remove the iron and let the wire and solder cool before bringing the iron back. If you overheat the insulation it will pull back from the copper and leave you with exposed wire risking a short. It will also get messy with melted insulation. The paramount technique here is to never have the tip of the iron in contact with the wire for more then one seconds, less is better.
If everything goes well, you should be left with perfectly tinned wires with just a bit more than 1/32" of exposed, tinned copper. Your wires are now ready to solder to a pad on the motherboard.
Before soldering your freshly-tinned wires onto the motherboard, it is highly recommended that you tin the pads on that motherboard. Tinning the pads on the board will improve the flow and will make a solid connection that is unlikely to short or break apart in the future. Below you can see an example of tinning a pad on one of our 21-HW adapter boards. Preheating the pad with the iron, feed your solder from the opposite side until the pad has an even flow of liquid solder. Then remove the solder and the iron. Do not put too much solder on the pad, or else it may run onto other pads creating shorts. It is only necessary to cover the pad evenly.
Below you can see examples of what a solder connection should look like. Note that the solder is evenly flowed over each pad and wire, and there are no exposed wire strands. By using the techniques described in this guide, you can live worry-free about short circuits and poor connections in your locomotives!