There's not an Arnold U25C listed in
@jdcolombo 's Loksound install list, so here's one to fill that void.
Pictures can tell the story better than I can, but I'll add a few captions along the way.
1) First, I removed the PB pickup tabs from the PC board, trimmed the pickup "nubs" from the trucks flush with the the tops of the trucks, and hard-wired the truck pickups to the PC board. This improved the pickup between the trucks and the PC board, and it created needed space for the decoder and speaker.
2) Next, I removed the top part of the frame and "notched" the rear to create some room for a pair of 330uF 20v caps.
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3) As I've seen others here do, I removed the shrink-wrap from the Loksound Nano, de-soldered the Aux wires that weren't needed, and added a green wire to the GND pad for the addition of the capacitors. Then, I wrapped the decoder with kapton tape.
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4) I clipped-off the 6-pin decoder socket and soldered the wires from the Nano to their respective pins. The decoder itself was taped to the underside of the PC board above the rear truck.
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5) A pair of 330uF 20v caps were sandwiched together, soldered to the blue and green wires, wrapped in kapton tape, and tucked into the notched space between the decoder and frame.
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6) The speaker wires were routed over the top of the board to the front of the locomotive, connected to the 12mm x 8mm Sugar Cube speaker & enclosure, and the speaker/enclosure was taped to the underside of the PC board above the front truck. The kapton tape also insures there's no contact between the contacts on the speaker and the front truck. To my ear, there's no interference caused by the tape with the quality and volume of the sound.
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7) That completes the install! This is one of the less-painful installs I've done, considering the minimal about of frame modification required.
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Update 5/12/2022 - Here's a video, so you can hear it in action.
