This installation is for Micro Trains line Z scale SD40-2 and features the MZA4 decoder.

       Remove the body shell and handrails by gently pulling up on the shell. ┬áRemove the fuel tank.

Next remove the screws highlighted in the image below and remove the original lighting board.

Next the frame posts need to be slightly modified before the MZA4 will fit in the frame.

The three pictures below show the "New"Style chassis before posts modification.

 

The Three pictures below show the posts modification we did here at TCS. It will allow you to use MZA4 decoders in the new MTL Chassis style.

Using a dremel tool (on the SLOWEST speed setting) with a cut-off wheel cut into the notches in the frame and remove approximately half of the material between the notch and the outside wall of the post. The cut should proceed straight toward the outside of the frame and care must be taken to avoid making the notch any wider (.001"-.002" of extra cutting down into the post or up towards the top could prevent the decoder from fitting snuggly). The image below shows the completed modification.

Now reinstall the motor and place the MZA4 into the notches in the posts (as seen below), and replace the three screws that were removed.

Last the motor springs (not shown) must be looped through the small, motor pick-up holes (to the left of the of the frame posts above) in the decoder. Be sure that the springs will not contact the frame before replacing the shell and powering the locomotive.