Atlas RS1 N Scale M1 Decoder Installation

Atlas RS1 N Scale M1 Decoder Installation

Photos and write up by Eric Bufkin

Atlas Classic RS-1 Decoder Install

A couple of years ago, I bought an Atlas Classic RS-1. I didn’t need one, didn’t know much about the prototype, and had no idea what I was going to do with it. It was a total impulse buy. It had a certain cuteness factor that I couldn’t pass up. Since then I have acquired a second RS-1 and I have begun using DCC. This required an upgrade to my RS-1s for DCC operation.

When Atlas first designed this locomotive, DCC wasn’t nearly as popular as it is today. There was no room for a decoder under the shell. But, Atlas was using the split frame technology. The split frame makes the DCC install much easier. Another advancement in technology also helps with this install. And that is the size of decoders. Over the years they have gotten smaller. This is a big help in locating decoders in locomotives that don’t have room for decoders.

I used the following steps to install a TCS M1 decoder in my two RS-1s. I really like the way the TCS decoders controls the locomotives. They are two of my best performers now.

Step 1 – Modifying the frame.

To get the decoder to fit, part of the frame must be cut away. Aztec Manufacturing can do this for you at a cost of $10. Or you can pull out your handy-dandy razor saw and do it yourself.

The first thing you will want to do it completely disassemble the locomotive so that you do not get any metal filings in the gears or motor. On the back of the left frame is a small tab to the rear of the opening for the worm. That has to be sawed off. If it is sawed flush with the lower section of the worm opening, the decoder will fit nicely. But wait, the right side also needs a section removed. The section to be removed on the right side is quite a bit bigger. You should be able to tell where it needs to be sawed to get it removed. Once it is removed you should have a nice area for your decoder to fit.

Continuing with the frame modification, you will need to remove the tabs that supply power to the motor. The arrow on the right points to location of the top tab. I just used a pair of pliers and bent it backwards until it broke off. The bottom tab will need to be removed with a saw.

One more thing you will need to do is grind out a channel on top of the frame halves where they meet to provide clearance for the wires.

Step 2 – Wiring the motor.

Once the frame is modified, you are ready to wire the motor. Put the frame together with the motor in it. Place the decoder in its location and cut the grey and orange wires to length. The orange wire goes to the bottom of the motor and the grey wire goes on top. (Note: I installed the wires backwards by mistake.) The Orange wire needs to be routed so that it does not get pinched by the frame when assembled.

Now, remove the motor brush caps from the motor. DON’T LOSE THE BRUSHES OR BRUSH SPRINGS! There is a small piece of copper that was used to conduct power from the frame halves. You do not need these anymore since your power will now come from the decoder. I simply trimmed them with a pair of wire cutters.

Solder the wires to the brush caps. You will want to keep your solder to the minimum to prevent a short. I soldered my wires on the beveled edge of the brush caps. You also want to make sure you don’t cover the small hole on top of the cap with solder.

Step 3 – The Lightboard

The front lightboard also needs some slight modification (the rear lightboard is removed in this type of installation). The trace to the LED needs to be cut. I used the back of a hobby knife blade and just scraped it across the trace a few times and used an Ohm meter to ensure it was isolated.

The two smaller arrows show where you will solder the red and black wires. The white wire will be soldered to the small solder joint just to the right of the cut trace.

I found that it is easier to go ahead and reassemble the locomotive before solder the red, black, and white wires. When done it should look like this:

Check to make sure your frame halves are isolated with an Ohm meter. Now carefully route the wires and place the decoder in the recess. Then replace the shell and you’re done.

I hope this helps anyone who wants to install a decoder in their RS-1.