This installation is for N Scale Kato SD40-2 uses the TCS K1D4 Decoder and was performed by TCS.
First remove the shell by grasping the locomotive on either side, squeezing gently (be sure your fingers are not holding the guard rails) and gently wiggling it back and forth until it slips up and off the chassis.
Next, remove the lighting board by pulling it towards the back of the locomotive and lifting it up and out.
Now wrap a piece of kapton tape around the frame (all the way from the engineer side to the fireman side) above the motor tabs. The image below shows the completion of the process.
Reverse the process you used to remove the lighting board to insert the K1D4. First place it into the notches in the frame, then slide it forward. Make sure the motor clips on the decoder are fully covering the motor pickups on the locomotive. The fireman's side typically slides right over, but the engineer's side will require a bit more care. The following two images show the motor clip covering the motor tab and the K1D4 installed.
You can now replace the shell of your locomotive and you are ready to run!
Important Soldering Tip
Please do not use any flux either liquid or paste on the mother board. 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.
You can order this solder from the following retailers:
Digikey - PN:KE1110-ND
Techni-Tool - PN:488SO6775
Other solder tips
When stripping wire, only strip a tiny little bit of the insulation. Strip no more then a 1/64 of an inch. When the wire gets tinned with solder, the insulation will shrink back more. Try to not expose any more wire then half the length of the solder pad at most. In no case should solder or exposed wire wire ever be outside the boundary of the the solder pad you are attaching a wire to.
Click here for important information on properly Stripping and Tinning wire