Table of Contents

Introduction

The following detailed description covers installation of a Digitrax DN93FX decoder in a Life-Like Alco FA2 diesel, as actually performed by the author of this publication, and reflects the experiences encountered during the installation.

This is one of the easier DCC conversions to carry out, and is recommended for a first or early-on installation.

The Digitrax DN93FX decoder was used because it was "on hand." Several other decoders from Digitrax, Lenz, TCS, etc., could be used.

The most important factor to remember in performing an analog to digital conversion is to ensure both motor brushes and the decoder orange and gray wires are insulated from the frame. Any contact of the brushes and/or these wires with the frame may result in virtually instant destruction of the decoder.

The first step in the description which follows is to test the decoder for proper operation, following the instructions provided by the manufacturer. The purpose of this step is to ensure any non-operational or dead-on-arrival decoder can be repaired by the manufacturer under warranty.

There is no retroframe or modified rear weight available for this diesel, so your must modify the rear weight yourself to provide room for the decoder. Refer to the section below for instructions. There is no modification required to the front weight.

To install the decoder and modify the frame you will need the following tools:

You will be cutting approximately 1/4" off the top of the rear weight to accommodate the chosen decoder. When directed in the detailed installation instructions below, modify the rear weight of the FA2 as follows:

• Using the actual decoder mark the area on the ends and sides of the weight to show the exact depth required for the cut. Be sure the depth of the cut leaves at least 1/8" of metal above the opening in the bottom of the weight.

• Place the weight in a vise. Use a Hacksaw (preferable) to cut off the area marked, or a Dremel #106 1/16" diameter rotary engraving cutter or equivalent in a motor tool to grind away the marked area (remember to wear eye protection). Smooth the sharp edges of the cut with fine sandpaper to ensure the insulation on the decoder and decoder wires cannot be pierced.

• Use 600 grit wet and dry sandpaper to polish the weight.

You can now continue to install the decoder per the detailed instructions which follow.

Set your browser left and right margins to 0.5" (File Page Setup) and print out this document. As each step in the installation is completed place a "X" or a check-mark through the bullet. All references to the frame are based on the front being at the top or away from you.

In normal analog (DC) operation, the right motor brush is connected to the right rail and the left motor brush is connected to the black rail. Life-Like uses an odd combination of color-coded wires to connect the motor brushes to the trucks. The front trucks are connected with blue-colored wire and the rear trucks are connected with red-colored wire, one wire each side.

• Begin by testing the Digitrax DN93FX decoder for proper operation per the instructions provided by Digitrax.

• Cut the decoder wires as follows, then strip 1/8" insulation from the ends:

• Note: The FA2 does not have a rear headlight. It is suggested the yellow and green decoder wires be cut to 1/2", leaving a length that can be used should the decoder be later installed in another locomotive.

• Remove the FA2 shell by spreading the bottom of each side of the shell carefully with your fingers and lifting upwards then forwards to clear the front coupler until free. Set aside.

• Remove both the front and rear weights from the locomotive.

• If you are replacing the Rapido couplers with other couplers such as Micro-Trains, Unimate or Kato couplers do this now.

• Modify the rear weight following the instructions in the section above.

• All electrical connections are made to the motor brushes. The right motor brush is connected to the front truck by a blue wire and the rear truck by a red wire, both on the right side of the frame, and the left motor brush is connected to the front truck by a blue wire and the rear truck by a red wire, both on the left side of the locomotive. The two black wires from the headlight connect one to each brush terminal.

• Carefully unsolder the existing wires from the motor brush terminals.

• Place the modified rear weight in place on the frame and tape the DN93FX decoder to the top with the wires facing towards the front of the locomotive.

• Solder the orange decoder wire to the right motor brush terminal, and solder the gray decoder wire to the left motor brush terminal.

• Solder the red decoder wire to the right-hand blue and red wires from the FA2 front and rear trucks. Insulate the joint.

• Solder the black decoder wire to the left-hand blue and red wires from the FA2 front and rear trucks. Insulate the joint.

• Solder the decoder blue wire to one of the black wires from the headlight, and insulate the joint. Solder the decoder white wire to the other black wire from the headlight, and insulate the joint.

• Using an ohmmeter, check for shorts between the two motor brushes and the frame and trucks. Resolve any problems before continuing.

• Dress all wires away from the drive mechanism and test operation of the locomotive. Resolve any problems before continuing. (Note: dirty wheels can adversely affect locomotive performance.)

• Locate the headlight in its proper position and replace the front weight on the locomotive. Tape the headlight wires to the weight.

• Carefully dress all the wires so they do not interfere with either the mechanism or the replacement of the shell.

• Carefully place the shell on the frame and press down, being careful not to catch any of the wires, until it clicks in place.

• Test the operation of the locomotive on the railroad. It should operate just as if no modifications had been made. Resolve any problems.

• Place the locomotive on the DCC programming track and set the DCC Command Station to the programming mode.

• Program Configuration Variable "CV29" to "06" for 2-digit addressing or "38/x26" for 4-digit addressing then program the decoder to the desired address.

• Carry out a final check of the locomotive on the railroad.

• Record the decoder CV's and address, and the reporting marks of the locomotive.

The conversion is complete. Enjoy your DCC-equipped locomotive.

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Last updated: Saturday August 1, 2009

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