Here is what the stock chassis looks like before milling. Note the two post where the stock decoder screws down onto. There are recesses on top of the chassis on either side and I milled the top down even with the depth of these recesses.
Each end is slightly different with the front getting.056” milled off and the rear getting. 031” off.
In an engine this small it’s a legitimate concern removing weight from the chassis but in reality it is a very small amount. I weighed the chassis before and after milling and a total of .56 grams of metal was removed to make room for the electronics. However when you add back the decoder and other components it more than makes up for the material removed.
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The rear cut remains square up to the motor. The front where the decoder resides needs to be filed at an angle to make room for the wires and allows the decoder to mount slightly lower. The angle cut is just to the top of the motor.
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The frame was drilled and tapped for 00-90 screws. The track pickup wires get pinned under the screws.
The decoder used is a 58923 Loksound v5 Nano DCC. I cut the shrink wrap off to gain access to the wires on the adapter board. I unplugged the adapter then unsoldered and removed the green and violet function wires as the white and yellow were the only ones needed. I soldered one of the green wires to the GND pad to connect the power keeper to later.
Carefully routing the wires allowed them to lay flat in a single layer.
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The decoder was taped wires down which keeps things neat.
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It uses an 8x12 Soberton speaker. Digikey pn 433-1130-ND. Mfg # Sp-1208. The speaker enclosure was built from strips of .015 styrene 3mm tall with just the four walls and no floor. I covered the back frame cut with 1/2” kapton tape then sealed the open bottom of the open enclosure with Gallery Glass. This gave just a little more interior volume of the enclosure by not having the thickness of a styrene floor. The speaker was then sealed down to the top of the enclosure walls. Anopy cement or Micro Krystal Klee would work as well for sealant.
The green wire from the GND pad and the blue wire were soldered to the + and - pads on the Run-N -Smooth power keeper. There was enough slack left in the wires to tuck the power keeper up into the cab as the chassis is inserted into the shell.
0603 LEDs with magnet wire were taped to the top of the decoder and speaker aimed at the lenses in the shell. 3k 1/8 w SMD resistors were soldered in-line with the white and yellow function wires connected to the - cathode magnet wire with the anode + magnet wires connecting to the blue wire at the power keeper.
The install can be done without the power keeper but I highly recommend using it because it helps quite a bit with the running characteristics.
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