Athearn Roundhouse - EMD Model 40

Scale:
HO Scale


This installation uses the following decoder:




This installation documentation is for the Athearn Roundhouse EMD Model 40 Switcher. This installation uses the KAM4-LED decoder and was performed by Carson of TCS.

 

Here is an article on the prototype of the EMD Model 40 found here.

Side view of the Model 40 before installation.
Side view of the Model 40 before installation.
Front view of the Model 40 before installation.
Front view of the Model 40 before installation.
Another front view of the Model 40 before installation.
Another front view of the Model 40 before installation.
Remove the coupler pocket screws on each end (circled in red) and remove the couplers.
Remove the coupler pocket screws on each end (circled in red) and remove the couplers.
Remove the two screws (circled in red) to remove the underframe.
Remove the two screws (circled in red) to remove the underframe.
Here is underframe removed.
Here is underframe removed.
Gently grab the shell and pull up. Be careful with the handrails.
Gently grab the shell and pull up. Be careful with the handrails.
Here the shell is removed. There will be 4 wires running to the LEDs in the shell. Be careful not to tug on them.
Here the shell is removed. There will be 4 wires running to the LEDs in the shell. Be careful not to tug on them.
Remove the circuit board from the factory double-sided sticky tape.
Remove the circuit board from the factory double-sided sticky tape.
Unsolder all of the wires outlined in the red box. Also unsolder the LED wires running to this board.
Unsolder all of the wires outlined in the red box. Also unsolder the LED wires running to this board.
Guide of which wires are which coming from the frame of the locomotive.
Guide of which wires are which coming from the frame of the locomotive.
The LEDs are pushed into the shell by press-fit.
The LEDs are pushed into the shell by press-fit.
Push the LEDs out of the shell, either by using your finger or the back end of a screw driver. We don't want to use the normal end of a screw driver since it will damage the shell.
Push the LEDs out of the shell, either by using your finger or the back end of a screw driver. We don't want to use the normal end of a screw driver since it will damage the shell.
Before we start soldering, we will remove this bracket to allow more room for the decoder and wires.
Before we start soldering, we will remove this bracket to allow more room for the decoder and wires.
Screw back in the screws and little copper washers. Since they are used to conduct track power from the frame.
Screw back in the screws and little copper washers. Since they are used to conduct track power from the frame.
Shorten the Orange wire coming off the decoder to a manageable length with some wire snippers. Solder the Orange wire (Motor +) coming off of the decoder to the Red (Motor +) wire. Use heat shrink to seal and protect the wires.
Shorten the Orange wire coming off the decoder to a manageable length with some wire snippers. Solder the Orange wire (Motor +) coming off of the decoder to the Red (Motor +) wire. Use heat shrink to seal and protect the wires.
Shorten the Grey wire coming off the decoder to a manageable length with some wire snippers. Solder the Grey Wire (Motor -) coming off the decoder to the Black (Motor -) wire. Use heat shrink to seal and protect the wires.
Shorten the Grey wire coming off the decoder to a manageable length with some wire snippers. Solder the Grey Wire (Motor -) coming off the decoder to the Black (Motor -) wire. Use heat shrink to seal and protect the wires.
Shorten the Red wire coming off the decoder to a manageable length with some wire snippers. Solder the Red Wire (Track Right/Fireman Side) to the Red wire coming off of the copper washer. Use heat shrink to seal and protect the wires.
Shorten the Red wire coming off the decoder to a manageable length with some wire snippers. Solder the Red Wire (Track Right/Fireman Side) to the Red wire coming off of the copper washer. Use heat shrink to seal and protect the wires.
Shorten the Black wire coming off the decoder to a manageable length with some wire snippers. Solder the Black Wire (Track Left/Engineer Side) to the Black Wire coming off of the copper washer. Use heat shrink to seal and protect the wires.
Shorten the Black wire coming off the decoder to a manageable length with some wire snippers. Solder the Black Wire (Track Left/Engineer Side) to the Black Wire coming off of the copper washer. Use heat shrink to seal and protect the wires.
Use some electrical tape to secure the Track and Motor wires to the frame.
Use some electrical tape to secure the Track and Motor wires to the frame.
Use TCS's 4-Point Junction Board (SKU: 1518) (https://www.tcsdcc.com/product-page/4-point-junction-board) Solder the Blue Wire (12V+) to one pad on the junction board and the Red wires coming off the LEDs to any 3 of the remaining pads. This allows for an easy distribution of the 12V supply for the LED Headlights. No splicing or soldering wires together!
Use TCS's 4-Point Junction Board (SKU: 1518) (https://www.tcsdcc.com/product-page/4-point-junction-board) Solder the Blue Wire (12V+) to one pad on the junction board and the Red wires coming off the LEDs to any 3 of the remaining pads. This allows for an easy distribution of the 12V supply for the LED Headlights. No splicing or soldering wires together!
Since this locomotive only has 2-functions, we will snip both the Green (F1) and Purple (F2) using a pair of wire cutters, to a decreased length. Since there is not a lot of room in this model, we want to have as little extra wires as possible.
Since this locomotive only has 2-functions, we will snip both the Green (F1) and Purple (F2) using a pair of wire cutters, to a decreased length. Since there is not a lot of room in this model, we want to have as little extra wires as possible.
Here is both of the wires shortened.
Here is both of the wires shortened.
Using some double-sided sticky tape, measure a strip about the same dimensions as the decoder. Then apply it to the back of the decoder and place it on the frame on top of the taped down wires.
Using some double-sided sticky tape, measure a strip about the same dimensions as the decoder. Then apply it to the back of the decoder and place it on the frame on top of the taped down wires.
Shorten the White wire coming off the decoder to a manageable length with some wire snippers. We will not need resistors for the LEDs since the decoder already has built-in resistors. Solder the White wire F0F (Function 0 Forward Headlight) coming off of the decoder to one of the black wires coming off of an LED. Use heat shrink to seal and protect the wires.
Shorten the White wire coming off the decoder to a manageable length with some wire snippers. We will not need resistors for the LEDs since the decoder already has built-in resistors. Solder the White wire F0F (Function 0 Forward Headlight) coming off of the decoder to one of the black wires coming off of an LED. Use heat shrink to seal and protect the wires.
Shorten the Yellow wire coming off the decoder to a manageable length with some wire snippers. We will not need resistors for the LEDs since the decoder already has built-in resistors. Solder the Yellow wire F0R (Function 0 Rear Headlight) coming off of the decoder to the other black wire coming off of the LED. Use heat shrink to seal and protect the wires.
Shorten the Yellow wire coming off the decoder to a manageable length with some wire snippers. We will not need resistors for the LEDs since the decoder already has built-in resistors. Solder the Yellow wire F0R (Function 0 Rear Headlight) coming off of the decoder to the other black wire coming off of the LED. Use heat shrink to seal and protect the wires.
Push the LEDs back into the headlights.
Push the LEDs back into the headlights.
Put the shell back on the frame. Make sure that the wires clear the shell and that no wires get pinched.
Put the shell back on the frame. Make sure that the wires clear the shell and that no wires get pinched.
Re-attach the underframe with the two screws you took out earlier and reinstall the couplers.
Re-attach the underframe with the two screws you took out earlier and reinstall the couplers.
Just like that you have a Athearn Roundhouse EMD Model 40 equipped with a TCS KAM4-LED and built-in KeepAlive®!
Just like that you have a Athearn Roundhouse EMD Model 40 equipped with a TCS KAM4-LED and built-in KeepAlive®!
With the built-in KeepAlive®, this small wheelbase model will have no trouble going over switches or problematic trackwork!
With the built-in KeepAlive®, this small wheelbase model will have no trouble going over switches or problematic trackwork!

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 than a 1/32 of an inch. When the wire gets tinned with solder, the insulation will shrink back more. Try to not expose any more wire than 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