N-Scale Intermountain FP9(A) with the TCS IMFP4 decoder installed - performed by J.M.
First remove the front coupler by removing the screw highlighted in the image below and sliding the coupler out of the shell.
Next, rock the shell back and forth until it slips off of the locomotive. Your chassis and lighting board should look like the image below.
Desolder the yellow and green wires from the lighting board. Be mindful of their positions because we must attach them to the IMFP4 in the same order to ensure the LED's polarity is correct.
Next remove the screws holding the lighting board in place and take out the lighting board. place the IMFP4 into the chassis just as the lighting board was and screw it in place. Solder the wires to the IMFP4 in the same order they were attached to the lighting board. Your installation should look like the image below.
Replace the shell on the 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