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Replacement Items

Replacement Frames for Easy Installation of Digitrax N Scale Wired Decoders

 DigiFrames by Southern Digital            Back To List

DigiFrames are cast frames specially designed for Digitrax. DigiFrames material is especially formulated to retain the high strength, tolerances and weight demands for digital command control conversions. Order from your Digitrax Dealer or Direct from Southern Digital (770) 929-1888

Available Direct from Aztec Manufacturing (775) 883-3327

Track Master™ Replacement Frames for N-Scale. Aztec will machine your frames to fit Digitrax decoders. "Track Master™ frames are the only after market frames approved by Atlas and Kato." These are factory frames that are precision milled to give a perfect fit for Digitrax decoders.
Replacement Frames for HO Kato NW-2 Available from Brinton Jones

Factory frames milled for HO Scale Kato NW-2. Kato authorized, these frames do not void manufacturer warranty. $18.20 exchange. Contact Brinton Jones (510) 471-1616 bmrjones@pacbell.net  30993 Huntwood Ave #206  Hayward, CA 94544-7000

Read these Instructions TWICE before you do anything else!!!

Test the Decoder                                         Back To List
All Digitrax decoders are tested for proper operation before they leave the factory, but sometimes strange things happen.  Therefore to insure your decoder is covered under our warranty policy, please give it a thorough test BEFORE you cut the wires.


Test Run the Locomotive
Be sure it runs correctly in both directions with no unusual noises or binding in the motor-gear train.
If it checks out OK, then:


Get Ready
Before you start, get your tools and supplies together for this project.
You will need the following items:

  • DECODER TESTER - Such as the one that came with your Digitrax system or any other RELIABLE DCC decoder tester.
  • TWEEZERS - Small sharp pointed
  • FILE - Medium size, fine tooth
  • PARTS LIST - The one that came with your locomotive.
  • PARTS CONTAINER - Something to keep the parts in so the won't get lost.  The box the locomotive came in or a small zip top bag will work fine.
  • MARKER PEN - One that will mark on metal and plastic.
  • A DAB OF 'GOO'
  • And, of course, the locomotive

Please Note:  This installation will not allow you to keep the headlight feature, however you will be able to retain nearly all of the weight of the locomotive which is very important with a locomotive of this small size.




Put ALL of the parts into your parts container as they are removed in the following steps.  Referring to the parts list and disassembly instructions that came with your locomotive, gently pull out the top ends only of the hand rails on both sides of the cab rear door.  While gently rocking the cab, pull it straight up and off.  Remove the weight found inside the cab.  Remove the plastic fuel tank cover by pulling it straight away from the frame.  Grasp the frame in one hand and the walkway/shell combination in the other and carefully pull the two apart.  The trucks may now be removed by rotating slightly and lifting them out. (They will practically fall out at this point.)  Pay attention to their orientation with respect to the frame in order to reassemble them properly later.  Remove the plastic screw head covers and the screws holding the frame halves together.  Remove the small printed circuit light board and the two insulating frame separator/spacers.  Very important:  Before removing the motor, make a PERMANENT mark on the TOP of the motor so you will know which wire to connect where and how to re-install it.  Snap the motor carefully out of its plastic mounting frame.  You will find a small phosphor-bronze contact tab at each motor brush cap.  With your pliers, grasp the tab and pull each one straight out from under the brush cap.  Be careful not to bend them, as they will be used in another manner later.  Inside the brush caps are the carbon brushes and small delicate springs.  CAREFULLY grasp the brush caps with your pliers and gently pull them straight out from the motor.  They are "snapped" in place and a slight rocking while pulling motion will free them.  Do this carefully so as not to loose the small springs inside nor to bend   the cap out of shape.  Believe me, the springs are nearly impossible to find if they hit the floor!!!   Be sure all of the parts except for the frame halves are in your parts container and close it up.


Frame Modification

At the front end of each frame half, you will see a groove which held the light board.  When making the modification described below, be sure not to remove any metal below the BOTTOM of this slot.  Referring to the picture above, mark the area to be cut away on each frame half. You may find it useful to clamp the frame half in a small vise to hold it while doing the cutting.  Be sure there are no sharp edges left which could cut through the insulation of wires or the plastic wrapper of the decoder.


Wiring and Assembly

Temporarily reassemble the frame halves, motor, motor mounting frame and insulating spacers with the screws and plastic nuts.  Tighten the screws only until they are just barely snug to keep the motor from falling out.  Notice that on one side of the DZ121 there is a large square bump at the opposite end from the wires.  This side of the decoder will be down to fit properly when installed.  Cut off the BLUE, WHITE and YELLOW lighting wires as close to the decoder as possible.  They are not used in this installation.  Be sure the exposed ends can not touch anything when the decoder is installed. You may need to trim the shrink wrap back on the ends of the decoder.  Do this very carefully with a sharp blade in your hobby knife. Be very careful not to cut the wires or their insulation with the hobby knife.   Cut the GRAY wire to 1 3/8" (35 mm).  Cut the RED, BLACK and ORANGE wires to 1 1/8" (28 mm).   Strip about 1/16" (2 mm) of the insulation off all of the wires and apply a small amount of solder to tin them.    Apply a small amount of solder in the groove on the top edge of both brush caps.  DO NOT ATTEMPT TO DO THIS WITH THE CAP ON THE MOTOR!!!  THE PLASTIC MOTOR HOUSING WILL MELT AND DISTORT AT A VERY LOW TEMPERATURE AND WILL BE RUINED!!!  Cut one of the "ears" off each of the phosphor bronze brush cap clips and solder one to the RED wire and one to the BLACK wire bending the remaining "ear" on each clip over the wire. 

Take the screws and nuts out of the frame halves and remove the motor from it's mounting clip. Install the brush, spring and cap attached to the GRAY wire in the bottom brush opening of the motor.   Keep it against the frame and out of the way of the motor worm gear and out of the way of the truck gears with a dab of 'goo' (later).  The GRAY wire is routed through the end of the motor mounting clip and beside the motor shaft to the top side of the locomotive.  Clip the motor back in it's mounting clip. 

Install the ORANGE wire, remaining brush cap and brush and spring in th top motor brush opening.  Be sure there are no wire "whiskers" that could contact the locomotive frame.  Wires can be "shortened" after assembly by rotating the brush cap to take up a bit of the slack.  Reassemble the motor, mounting clip, insulating separators and frame halves with the two screws and plastic nuts.  SNUG BUT NOT TOO TIGHT!!! 

Slip the phosphor bronze clip with the RED wire attached down between the plastic part of the motor and plastic motor mounting clip.   The end of it will contact the right metal frame half (engineer's side) when assembly is complete next to, but not touching the brush cap.  Install the clip with the BLACK wire similarly on the left (fireman's side).   Be sure there is no contact between either of the brush caps, their wires nor metal parts of the motor and either of the clips attached to the RED and BLACK wires or you will have SMOKE!!! 

In the corner where the GRAY wire is routed, use a toothpick to place a small amount of  adhesive (Walthers "GOO" or similar) to hold the GRAY wire in position away from the gears and motor shaft.  When the adhesive has thoroughly dried, rotate the trucks back into their respective, properly oriented positions.  Check that there will be no interference between wires and parts of the locomotive frame, motor and shell and then place the locomotive shell and walkway back in place. Be careful with the metal contact parts on the bottom of the walkway getting back into proper position with the electrical contacts on the trucks.  These metal parts are easily broken off from the shell and difficult to reattach!  (Voice of experience)



Test Run
Place the locomotive on your DCC track and check that it runs OK in both directions with no binding or unusual noises.  (Due to the track power pickup configuration, it won't run without the shell in place!)  If all is well, put the weight and cab back in place and enjoy.


Athearn N-Scale P59PHI
                                                        Back To List

The Athearn N-Scale P59PHI was not designed for a plug ‘n play installation therefore, a wired installation will be necessary.  This installation is straightforward if you follow the instructions provided below.  There is plenty of room inside the locomotive for this installation. 

Athearn N-Scale P59PHI Installation Instructions for Digitrax Decoders:

1.     Remove the locomotive’s shell.  Note which end of the frame is the front and which is the back.

2.     Remove the light board that is installed on the top of the frame.  Do this by removing the cylindrical black spacers and lifting the board out of the locomotive.

3.     Remove the metal contact strips that run from the top of the locomotive to the motor brushes on each side of the gray case that holds the motor.

4.     Use a sharp knife to remove the gray plastic bars from across the openings on each side where the metal tabs were removed to leave room for routing the wires from the decoder to the pickup tabs and brush contacts.

5.     Place the decoder on top of the frame in the area where the light board was located.

6.     Cut the red and black wires slightly longer than the distance needed to reach the brass track pickup tabs at the bottom of the slot below the motor brush contacts, bend the pickup tabs in slightly and solder the red wire to the right side (engineer's side) tab and the black to the left side.  Be careful that there is no contact created between the brass pickup tab and the motor brush contact when you solder the wires in place.  The insulation on the wires should extend below the brush caps to prevent contact with the brass pickup tabs.

Cut the orange and gray wires slightly longer than the distance from the decoder to the motor brush contacts and very carefully solder the orange wire to the right side and the gray wire to the left side motor brush contacts.  Again make sure there is no contact between the motor brush contacts and the brass pick up tabs.

Secure the decoder and wires with tape across the top of the locomotive frame.

To install the lights in the locomotive, you can remove the LEDs and the resistor from the light board that came with the locomotive and install them with your decoder.  You can also install white LEDs if you wish. Use the decoder’s white and blue wires for the front light and the yellow and blue wires for the rear light.  Cut the blue wire and install the resistor in line between the decoder and either LED.  Use shrink tubing around all solder joints to protect against shorting wires to the frame of the locomotive.                         

Installation of Digitrax DH121 in  Bachman Hogwart’s Express

Many thanks to Dick Sutcliffe, Superintendent BR &T Railway Co. for this application note!

Install the DN121 in the tender       Return To List
  1. The tender is easy to open by removing two screws so you can pull the decoder out and put in a plug when running on DC layouts.
  1. Use a piece of styrene to raise the decoder off the weight.
  1. Notch the front edge of the tender frame to bring the wires through to loco (all power pick up is in the loco).
  1. Split the loco frame to isolate the motor brushes, remove the contact springs in the frame & heat shrink the wires to the brushes.
  1. I drilled & tapped a couple of 2/56” screws into the frame halves for the track pickup connection.
  1. Runs quite well but I am planning to put wipers on the tender wheels to spread out the pickup and improve operation


Thomas the Tank Engine (with moving eyes) by Bachmann


Always completely disassemble the engine to determine space limitations.    In the disassembly  use the instructions if available . Bachmann has decided for this model to provide a removable cab.  With the cab removed there is  scads of room to put in a decoder and maybe some weight .    


  When I decoded the Hornby James and Duck they were immediate shorts.  In defense, Hornby's three-pole motor needs a little help.  So, they added a capacitor in parallel with the motor.  This is great when your track is running DC and does a fantastic job of smoothing out the rough edges but on a DCC layout with AC present on the track the capacitor acts as a dead short.  I immediately clipped these little darlings out on the Hornby's, as I had no further use for them.  On the Bachmann Thomas they had also used a capacitor in parallel with the motor but was not as harmful.  The designers had placed some resistance on the trackside leads to prevent a direct short from appearing and tripping the booster.  Nevertheless, it may be prudent to remove this nasty circuit and let the new decoder circuits handle the mess rather than try to fix it with analog components.

To splice or not to splice, that is the question

With the cab off there is plenty of wire.  You could really just clip and splice.  A few minutes and… wha-la ...the job would be over.  But…I decided that I really needed to do my normal engine service that includes:

  1. Remove all packing grease and re-lube. This, by the way, improved performance significantly.
  2. Check all wheels for gauge.  The Hornby models were all out of American HO gauge and had to be adjusted.  I really didn’t think the Bachmann model would be any different but was pleasantly surprised when all wheels were dead on gauge.

This meant removing all the parts.  While I was at it then, I decided to solder the joints at their origin rather than splice.

I started by cutting (or unsoldering) the red and black wires from the motor circuit board.  These will be orange and gray respectively from the decoder.  I elected to try it with the capacitor/resistor circuit still in.  In the commercial version we remove the circuit altogether. If you elect to try it without the circuit be very careful soldering directly to the motor as you may melt the plastic surrounding it.  Nothing bigger than a 15 watt iron and around 6 and no more than 10 seconds applying heat.  Kind of like spray painting, better to do it in two short bursts with it cooling off in between rather than one long one.  Also, tinning your wires for small stuff helps a lot.

Then, disassembling the undercarriage, I clipped (not de-soldered) the leads to the copper pickup strips.  This was fear of overheating these strips.  Any amount of heat will destroy this part.  Better, if you are not adept or faint of heart, to do the splice thing and not apply heat in this area.  Notice that you must thread the black and red wires through several parts including the wheel sets. (look at the picture...the first time I messed up!  Compare this with the first picture of the engine and you will see that there is supposed to be another part, the running boards and base that I forgot.  Had to unsolder, re-string the wire through the missing piece and solder again...(oh well). Another option is to put in a connector here.  I didn’t.


Ok, that’s about it.  What about the lights?  What lights?  This thing doesn’t have any lights…yet.  I put it together without the cab to do a quick motor test.  I wanted to see if the circuit board and the capacitors were going to be a problem.

Well, no problem.  And without putting lights in it, I decided to button it up and test for now.

Since there has been some confusion about the circuit board wiring we have elected to remove it.  It will not hurt the engine or its performance.

One more step…set the address.  As is customary, using the reporting marks on the engine, assign it the number…1.                  Return To List

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