The Bachmann NW2 is a very nice running engine and really shines when the stock electronics are replaced with a high quality decoder. In this case a Loksound 58823 wired version.
The shell is held on by 4 small nubs on the sides of the plastic motor housing. A toothpick inserted on each side to spread the shell slightly will allow it to be gently pried up and off.
Remove the Phillips screw holding the stock board down then clip off the four black track power wires and the blue and red motor leads.
I used a spruce cutter to nip off the posts where the stock board attached.
The sides of the plastic motor housing are slightly taller than the top of the motor so I shaved them down about .010” to allow the daughter board of the Loksound to rest directly on top of the motor after applying kapton tape to the motor and over the solder pads on the small board. The green and purple wires were not needed so were removed from the small board.
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The rear weight is a separate piece so I removed it and milled the top off almost flush with the top surface. The leftover little lip was to accommodate locating the stock light shield which is used to house a Soberton 8x12 speaker.
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I changed my mind mid install here and decided to seal the speaker housing directly into the cab. Having the decoder tethered to the shell for lighting or speaker bothers some and the enclosure could be left seated over the rear weight without a problem. Simple personal preference.
I cut the top out of the enclosure and will use the cab roof for the top of the enclosure. I think this gets a little more volume out of the speaker.
Since I lost the rear clear headlight insert somewhere in the process of painting the engine I filled in the small portion of the enclosure with styrene and embedded a 0603 LED to shine at the now empty cab light housing.
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The speaker fit perfectly front to back and a piece of styrene filled in the side to side difference.
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The enclosure was pushed in tight to the cab roof and sealed from the inside with Gallery Glass.
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Pieces of brown wire were soldered to the speaker pads then the speaker was placed into the enclosure and sealed around the perimeter with Gallery Glass. The front of the enclosure was trimmed up slightly to make sure there was enough room for the wires to clear the cab under the windshield.
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The decoder wiring is straightforward trying to keep the connections short behind the decoder. The green wire in the photo is soldered to the GND pad on the decoder and routed up to the negative side of the two 25v 220 capacitors.
3k SMD resistors were used in each of the light circuits with the white wire soldered to the resistor then the LED soldered directly to the other end and tacked to the capacitors with double sided tape. Magnet wire to the other side of the caps completed the headlight circuit. A second length of blue wire was routed back from the caps and connected to the anode lead of the rear light. A 3k SMD resistor was soldered to the yellow wire then the cathode lead from the rear light soldered to that and insulated in shrink tubing.
The speaker wires were connected back together and the shell snapped down on the chassis with ample room for everything.
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