Dead-Rail Conversion of an MTH PREMIER NORFOLK SOUTHERN SD60E DIESEL (O Scale, 2-Rail, PS-3.0): A Follow-up

To change things up, I showed you a “simple” Dead-Rail conversion of a Diesel locomotive in my previous post. This post follows up with an even more straightforward conversion that is very similar to what I do with steam locomotives: leave the DCC decoder and electronics in the locomotive alone except to provide a plug connecting the locomotive’s DCC decoder to an external Dead-Rail DCC source instead of DCC from the rails, which in our case will come from a battery-powered radio receiver and amplifier mounted in a “battery car” (the tender for steam locomotives).

Let’s see how this is done. I will repeat some steps so you do NOT need to refer to the previous post.

The Locomotive Conversion

The first step is to remove the locomotive shell so that we can modify the “2-Rail/3-Rail switch” and convert it to a “2-Rail/Dead-Rail” switch that will maintain the ability to use track power in either DCC or DCS mode and add the ability to use DCC from an external source.

Removing the upper plastic shell was easy; remove eight screws and the rear coupler. That’s one of the beauties of MTH locomotives: they are well-designed for disassembly.

There are four screws to remove at the front and rear of the “speaker pocket” in the middle of the locomotive.
The rear coupler must be removed to access the screws at the locomotive’s rear.
There are four screws to remove at the front and rear of the locomotive. The Kadee couple must be removed to access these screws at the locomotive’s rear.

Separating the chassis from the upper shell, we see the “stand holding the switch we’ll modify.

Side view of the locomotive Interior

Repeating from my previous post: To allow track-based “2-Rail” or “Dead-Rail” Operation, we need to figure out how to get DCC from either the track (“2-Rail Operation”) or from the output of the ProMiniAir Receiver’s Amplifier (“Dead-Rail Operation”). The original 2-Rail/3-Rail switch that routes track power/signal to the PS-3.0 is shown below.

The original 2-Rail/3-Rail switch routes track power/data to the PS-3.0.

These connections were verified by using a multimeter’s resistance-measuring capability. Let’s see how this switch is designed:

When the switch is in the 2-Rail position:

  • The Right Wheels’ output is directed to the PS-3.0’s DCC Track Right by shorting the “Track Right” end post to the “Track Right” center post.
  • The Left Wheels’ output is directed to the PS-3.0’s DCC Track Left since it’s directly soldered to the “Track Left” center post.

When the switch is in the 3-Rail position:

  • The Center Rollers’ output is directed to the PS-3.0’s DCC Track Right by shorting the “Track Left” end post to the “Track Left” center post.
  • Both the Left and Right Wheels’ output is directed to the PS-3.0’s DCC Track Left by shorting the “Track Left” end post to the “Track Left” center post and the “Track Left” end post’s jumper to the “Track Right” end post on the opposite side of the switch. This connection shorts the Right Wheel’s output to the Left Wheel’s output on the center post that then goes to the PS-3.0’s Track Left!

The photo below shows how to rewire this 2-Rail/Dead-Rail Operation switch.

The original 2-Rail/3-Rail switch has been rewired for 2-Rail/Dead-Rail operation.

Repurposing this switch has the following features:

  • The output from the center rollers is disconnected and closed off. Its role was only for 3-Rail Operation.
  • The Right and Left Wheels’ outputs are located on separate posts at one end of the switch (for 2-Rail Operation in either DCC or DCS mode).
  • The Track Right/Track Left DCC outputs from the ProMiniAir Amplifier are located on separate posts at the other end of the switch (for DCC Dead-Rail Operation).
Before/After switch schematics

After remounting the newly-modified 2-Rail/Dead-Rail switch back into its stand, the Dead-Rail wires leading to the switch are connected to wires that have an external plug that will receive Dead-Rail DCC from the “battery car” we’ll describe below.

The Dead-Rail connector from the 2-Rail/Dead-Rail switch to the small external Dead-Rail DCC connector.

A plug is “snaked out” near the rear coupler to connect to the external source of Dead-Rail DCC from the “battery car.”

The Dead-Rail connections between the “battery car” and the locomotive. That’s it: two wires.

Once we screw the upper shell back in place, we are done with locomotive modifications!

All we did was modify one switch and route the new switch connections to a small plug snaked out near the coupler. It can’t be any simpler than that!

Let’s turn to the straightforward “battery car.”

Battery Car Conversion

The photo below shows the components we fit inside a “battery car:” a 14.7V battery that will just fit through the door and a ProMiniAir Receiver/Amplifier. A surface-mount Molex 21004 antenna was mounted to the external metal shell. Surprisingly, reception worked, despite the traditional practice of avoiding antenna mounts on metal surfaces.

A straightforward “battery car” contains the battery and the ProMiniAir Receiver/Amplifier, and a surface mount antenna. Surprisingly, the surface mount Molex 211140 antenna worked OK when mounted externally to the car’s metal shell.

A small hole was drilled in the bottom of the car to pass Dead-Rail DCC from the ProMiniAir Amplifier to a plug that connects to the locomotive.

The small connector exiting the “battery car” that carries Dead-Rail DCC from the ProMiniAir Recevier to the locomotive.

Demonstration

With these Dead-Rail modifications, the video below shows Dead-Rail Operation.

The demonstration of Dead-Rail control using a Standalone ProMiniAir Transmitter controlled by a WiThrottle app on a smartphone. The DCC is wirelessly transmitted to the “battery car’s” ProMiniAir Receiver, providing high-power DCC to the locomotive.

Final Thoughts

The Dead-Rail modifications described here maintain 2-Rail Operation in either DCC or DCS mode, which mode is selected by the DCS/DCC switch.

The 2-Rail/3-Rail switch is repurposed as 2-Rail/Dead-Rail. The DCS/DCC switch is unmodified.

If the 2-Rail/Dead-Rail switch is set to “Dead-Rail,” then the DCS/DCC switch MUST be set to “DCC” so that the PS-3.0 can interpret the DCC signal coming from the ProMiniAir Receiver/Amp in the “battery car.”

This conversion was straightforward:

  • Modify one switch in the locomotive to receive DCC from an external source.
  • Snake a connector from this switch out of the locomotive near the coupler
  • Insert a battery and ProMiniAir Receiver/Amp inside the “battery car.”
  • Snake a connector from the Amplifier out of the “battery car”
  • Connect the two plugs together and couple the car to the locomotive.

I hope this simple conversion will inspire you to try your own conversion! There are locomotives such as PS-3.0-equipped MTH that will make this process easier.

Author: Darrell Lamm

I earned my Doctorate in Physics from the Georgia Institute of Technology in 1982, and before retiring in 2019 I worked for 37 years at the Georgia Tech Research Institute. My last position was Chief Scientist of the Electro-Optical Systems Laboratory. Like many people, my love for model railroading began at an early age, and I rekindled that interest starting in 2017.

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