Atlas MP15DC Decoder Install

Atlas MP15DC Decoder Install
I recently purchased this used Atlas MP15DC, and of course it needed a decoder. Since I’ve been more or less standardizing on Digitrax for my “run of the mill” decoders, I chose the Digitrax DN163A3, which is a “drop-in” version for this locomotive. TCS also makes a drop-in decoder, and of course a wired decoder can be used.

At low speed, this is one of the smoothest running locomotives in my fleet, even with the factory-default motor settings. There is an audible whine at higher speeds, but… this is a switcher. It’s not supposed to run at high speeds.

The install is so straightforward (and so typical of modern Atlas locos) that I won’t go into much detail here.

  1. Remove the shell
  2. Loosen the two frame shell screws
  3. Slide the light board out of the frame
  4. Place the decoder in the frame, with the large, wide end facing away from the cab end of the loco. Make sure to place it component side down, or LEDs up.
  5. Tighten the frame shell screws
  6. Replace the shell

The most important part of the install is to make sure the components face down when placing the decoder in the frame. The fit between the decoder tabs and the frame slots was quite tight, and required some force to get the frame to close up. If yours is loose, adding a little bubble of solder to the pads can take up the free space.

I also read in another install description that sometimes the motor tabs need to be trimmed or filed down just a bit to avoid incidental contact to the wrong tabs. I did not find this to be necessary on my loco, but be advised.

There was one thing that caught me off guard that I have not seen documented elsewhere, at least not with descriptive photos. There is a black piece of plastic inside the cab area of the shell that acts as part of a light guide for the rear headlamp. This piece is only press-fit, and seems to be able to fall out easily. Since I wasn’t expecting the part to fall out, I did not see where it fit originally, and it took some time to figure out where it went and how it fit into the loco.

To save you the trouble, here are a couple of photos:

The part is circled here.
Atlas MP15DC Decoder Install

This is where it goes… oriented upright like a chair, with the clear light guide poking through the hole in the black part.
Atlas MP15DC Decoder Install

One more tip… it’s easier to keep this light guide part in place if you flip the shell upside down and insert the frame into the shell, rather than placing the frame upright and putting the shell over it.

HTH!