Bachmann N scale 2-8-0
M1 decoder Installation

Photos and text by Michael Wong of Mahwah, New Jersey


Remove the tender by twisting it 90 degrees along the post.  The shape is keyed and being 90 degrees will allow the tender to come off. Remove the cab by gently prying up from the bottom.  Work slowly a little at a time alternating both sides.  The cab is in there pretty tight but itís only friction holding it in.  Think of it as an upside down ďUĒ clamp.  Once the cab is off, remove the weight. Rotate the front pilot as much as you can and unscrew the screw holding it in.  Remove the pilot and front stairs.  The top of the stairs just fit into the boiler shell via a stub and a hole on the boiler shell on each side.  The bottom of the stairs just slide out. Remove the boiler shell by lifting the rear up while sliding it forward.  Be careful on the right side as thereís an extra linkage attachment that is not on the left side.  You have to pop this loose or you will break it as the boiler shell comes off.  Once the shell is removed, the silver weight and the plastic insulator below it can be removed. 


Once the cab, boiler shell, weights, plastic insulator, pilot, and front stairs are removed, you should have something that looks like this.  Note the center power connection tabs with a pair of wires going to the light board and the other pair going to the motor.  There is a plastic clip that covers the power connection tabs (removed).  The connection is not soldered but rather it is friction fit with the plastic clip holding everything in.

Hereís a photo with all the parts removed.  Clockwise from upper left: cab, cab weight, power connection clip, pilot screw, pilot, front stairs, boiler weight, plastic insulator, locomotive, and the boiler shell. 


Next slide the light board out. 


Separate the lightboard from the motor leads and set it aside.  You will solder the two decoder wires to the board directly.  Next, trial fit the M1 in the space.  You may have to trim the clear shrink wrap as some of it may protrude causing the decoder not to fit.  Just trim it flush to the decoder printed circuit board. 


Next, trim and solder the blue/white wires to the light board.  By the way, the color coded wires in the locomotive match the wires on the M1.  Once the decoder wires are on the light board, you will have to slide the light board in first before seating the decoder.  Make sure the electrical tape under the light board is still there.  This is to prevent any shorts to the frame. 


Next, separate the remaining decoder wires.  Note that I trim the yellow wire and tucked it under the light board wires, just in case the decoder is used in the future in another locomotive.  Trim the red/black wire down and strip about half an inch of insulation off.  Twist the stranded wires so they donít fray while performing the next step.

Wrap the red wire to the right power terminal and the black wire to the left terminal.  Wrap each two turns tightly around their respective terminals.  This will give enough wire for the plastic clip to hold on to.  If there is extra wire after wrapping, cut them off.  Attach the plastic clip and make sure it secures the wires in place and make sure there is no stray strands shorting out the two terminal tabs. Next trim the orange/gray wires to the proper length.  The orange wire goes to the top motor cap while the gray wire goes to the bottom motor cap.  Use a low wattage soldering iron (I used a 25 watt one) as there is plastic holding the brushes in.  You donít want to melt it.  Do the soldering fast! Once the wiring is done, organize the wires and secure them with tape. 



Reverse the order of disassembly and assemble everything back.  Check for shorts and program the decoder on the programming track to make sure all the connections are correct.  Have fun!

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