This installation uses TCS AMD4 decoder and is for N-Scale Atlas GP40. Installation submitted by Alexander Clark.

Gently remove the 4 handrail ends from the cab by easing them out of their holes, gently pull the body off the frame by gripping it and the bogies, the body may come apart from the walkway when pulling apart, pull the fuel tank from the frame.


Mark the bogies and frame halves and note their orientation, remove the 2 screws securing the frame halves and gently prise the frame halves apart on the top just enough to release the original circuit board. Remove the led shrouds from the original board and fit to the AMD4 board. Test fit the AMD4 board into the frame lugs, they should be an interference fit and not to tight or loose. If it is too tight there are 2 options,

1- VERY GENTLY prise the lug apart, if using this method it is safer to repeat the operation several times rather than overdoing it the first time as there is a risk of snapping off the lugs

2 - Completely strip the frames and move the motor and gearing well away from the work area and using a needle file widen the gap, ensure the frame halves are clean before refitting the motor. If it is too slack, build up a little solder on the offending pads.



When the board will fit snugly into the lugs place a piece of Kapton tape on the frame where the motor tabs pass through the frame just below where the board will fit and rebuild all the parts in reverse order of strip down, when securing the frame halves with the screws do not over tighten them as they will cause the bogies to bind. Using a multimeter, test across the frames to check that they are no shorts.

Test the locomotive for operation and adjust any CV’s as required, refit the body and enjoy.

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