This installation is for N-Scale Athearn SD75I, uses TCS K1D4-NC Digital Decoder, and was performed by A.G..
The three upper pictures show the beautiful, highly detailed Athearn SD75I in N-scale.
First remove the shell by carefully pinching it on either side and rocking it back and forth while pulling upwards on it. The picture above shows the original light board that the engine is equipped with.
Remove the original light board and use some 1/2" Kapton tape to isolate the chassis from the decoder.
Slide TCS K1D4-NC decoder into the chassis as shown in the picture above.
Tint the copper pads of the decoder with solder.
Connect the decoder with the motor using Magnet wire.
Do the same to the other side.
Here is a picture of the finished TCS K1D4-NC decoder installation.