I just finished installing LokSound Select Micro Direct (73100) decoders into Atlas GP30 and GP9. This thread documents the install for the GP9.
First off is a video of the finished unit. I simply throttle up/down, with ESU's Drive Hold on, to rev the engines without having the loco move. At the end of the video are the install pictures discussed below
The GP9 is a DCC ready frame, and one which the 73100 works right out of the box! The only necessary adjustment is to mill the rear portion of the frame for the speaker install.
Here is a full view of the install. In this loco, you can see the full sized LED used for the headlamp, and a 1206 SMD LED used for the rear light.
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Here is looking down at the decoder from the top
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I put the Kapton tape along the top of the frame, just to ensure nothing contacted a component on the board. Probably wasn't necessary, but better safe than sorry. For this install, the two frame contact pads on the left are used, and I added some solder to them to help make the board sit into the frame's slot firmly.
Here is a view of the rear, with the custom speaker enclosure.
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Made from 0.020" styrene, the enclosure provides sufficient interior volume for the Soberton 8x12mm speaker. The enclosure's width is 0.357", and the height in the rear is 0.175". The length of the deep part runs 0.675 inches, with a 0.090" step to another 0.25" of length on the "porch". If one looks closely, between the enclosure and the board, just to left of the speaker (and large square chip), there is a 0.020" shim of styrene, which keeps the decoder and speaker apart.
On the stock frame, behind the worm gear retaining clip (the big brass clip), there is a small step up. This needs to be milled down, flat, to the height of frame at the clip
Below is the right-rear frame. On this side, the level of the frame is at the same height as the rear of the left frame from the step above the flywheel all the way to the rear. The frame must be milled down to be level with the milled left side.
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