ESU LokSound Micro Select Direct install in Atlas GP38-2

[RBrodzinsky]

I have successfully installed one of the new ESU LokSound Micro Select Direct decoders (73100) into an Atlas GP38-2.  This was a fairly easy but interesting install, due to the minimal amount of space available in the unit.

First off - the video.   Since this is not my loco, I left the hand-rail protective foam in place (which does mar the look of the video a bit)

Here, you can see the LokSound 73100 board, as compared to the stock NCE board.  The NCE board was not functioning well (needed >30% throttle to move, then minimal speed control, and no response from decoder even on programming track).  You can see that the 73100 is a bit shorter, and narrower in spots from the original board

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Here is the board in the chassis.  It looks like everything fits well, in the first photo, but on closer inspection, one can see that only the two front tabs are actually contacting the frame, and loosely.  The contacts for the rear position are inset a bit, and do not touch.  To ensure a snug fit and good contact, I ended up putting small blobs of solder on the front two pads, which now make excellent contact and hold nicely

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[peteski]

Thanks for this Rick - I was wondering how this "uniivesal" decoder would work on those Atlas locos.  It seems to work well. Now I see why the chassis contact pads are shaped the way they are.

[RBrodzinsky]

The real fun came in figuring out how to cram a speaker and enclosure into this little beast.  This photo shows the rear of the board and the overhang over the frame
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It isn't much space, compared to my "go to" Shapeways enclosure for the Soberton 8x12mm speaker
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So, I milled down the right side of the frame to match the left, and enlarged the lowered edge just a bit
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But even with that, and sanding down the bottom of the enclosure as far as possible, there was just not sufficient space. The top of the speaker would still be just at the bottom of the components (not a good thing).  So it was time for a custom enclosure.  I designed it to fit in the space under the board, and use the ledge over the flywheel to give me back some of the volume lost from shortening it.  After using thin styrene cement, and CA to attach the speaker, I also sealed all joints with Bondic, to ensure the enclosure was airtight.

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[RBrodzinsky]

Here is a side view of the speaker enclosure
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And, sitting in the frame (before I squared off the excess Bondic)
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It turns out that, for this model, the two little board mounted LEDs (Aux1 and Aux2) actually provide sufficient light and are positioned well for the front and rear headlamps, so here is the fully assembled unit

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I have not installed any added capacitors, and in playing around on my programming / test setup, had only one minor interrupt, on speed step 1/128, so I moved the Vstart to "2" from "1", and no further issues.

To help wedge the board in place, I put a 0.010" piece of styrene between the board and chassis in front, and a 0.020" piece in back, which also helped provide a bit more speaker/board separation.

[RBrodzinsky]

Thanks for this Rick - I was wondering how this "uniivesal" decoder would work on those Atlas locos.  It seems to work well. Now I see why the chassis contact pads are shaped the way they are.

Yes, I think these are a case of "it isn't perfect for each and every loco, but is perfectly adequate for them"   Took very minor adjustments (the shims and solder blobs).  The motor contact pads are perfectly positioned.

[jdcolombo]

Nicely done, Rick.

What are the dimensions of the speaker enclosure?

@Lemosteam:

I ask because John LeMerise might be interested in doing a 3D print for a "generic" enclosure like this.  It might be useful for a bunch of different locos of the same general chassis size/layout as the GP38 (e.g., GP40, GP50, GP60 maybe even the GP35, Alco C420, etc.).   Also, I wonder if that enclosure could have come out another mm or so toward the rear.  I don't know how much room you need on the back shelf for the rear light/numberboard assembly, but that looks like more than necessary.

And I wonder if there is room to stash a couple of keep-alive caps in the "lightbox" up front . . .

John C.

[RBrodzinsky]

The exterior height of the enclosure, at the rear, is 0.185".  The deep part is 0.572" long, then a 0.09" step, then 0.20" inches length on the upper porch over the fly wheel.  Width is the same as the current, 0.375".  Yes, about room for another 1-1.5mm, before there would be interference with the rear light pipe in this shell.  I cut the original space to fit John's current enclosure, so didn't go back to lengthen.

Not sure how "universal" this might be.  I was also asked to put a LokSound into an Atlas SD-35.  At first glance you would think these are the same frames, but they aren't! There is less space between the bottom of the board and the top of the brass spring clip.  I am studying it now, but will need to decide whether to tackle it, or suggest putting in a LokPilot. It has a completely dead NCE decoder at this point.

[RBrodzinsky]

Oh, and yes, if it turns out we need keep-alive, the front lightbox is where they will go. I can fit two of the 20V 220uF in there, if necessary.

[peteski]

The speaker enclosure is a perfect example of clever engineering.

[jdcolombo]

The exterior height of the enclosure, at the rear, is 0.185".  The deep part is 0.572" long, then a 0.09" step, then 0.20" inches length on the upper porch over the fly wheel.  Width is the same as the current, 0.375".  Yes, about room for another 1-1.5mm, before there would be interference with the rear light pipe in this shell.  I cut the original space to fit John's current enclosure, so didn't go back to lengthen.

Hey Rick - you're in N scale, which stands for 9mm.  Time to start using metric measurements 

It's kind of funny.  My wife alters and makes custom wedding gowns.  She can do nearly perfect inch measurements by sight.  Half inch, quarter inch, eighth, whatever.  I can't do that, but I can tell you pretty much exactly what 10mm is (the inside width of most narrow-hood diesels) or 6mm (the height of John LeMerise's 8x12mm speaker enclosure).  I can't reliably deal with kilometers, liters, kilograms, or pretty much anything else metric, but get me at my workbench and I'm a mm machine

John C.

[peteski]

Funny, even thought I grew up (in Poland) immersed in the metric system, after living in USA for 38 years I am more used to the imperial measurements.  When doing woodwork or larger home improvement projects I do use the fractions, but for N scale I use decimal notation of the imperial measurements. After all, most scratch-building materials (like sheet styrene) come in imperial thicknesses (like 0.020").

[RBrodzinsky]

LOL! It is just that my handy-dandy General Tool stainless pocket measure is in inches!   At least my digital caliper is all three (fractional imperial, decimal imperial, decimal metric)

[Steveruger45]

 Nice install Rick.
Your install is  pretty much just what I have in mind to do next on a FVM GP60 that I just got. Frame mods on the FVM will be pretty much the same too.

[Steveruger45]

Hey Rick,
I am looking at your install on this one and it looks like it would be possible to install the 73100 with the wide aft contacts as the primary contact. This would move the decoder fwd about 5 to 6 mm and give more room aft for a standard speaker enclosure.  This would shift the motor contacts fwd too, so I guess motor connection would have to be hard wired.  Question then would be would there be just enough room in the cab area with the board in the described position?
Would this idea fit ?
Thanks

[RBrodzinsky]

Steve, I did look at that, but anything more than 2.5-3mm would then interfere with the front light pipe. It extends back about half the light shield area. Plus the hassle of the motor contacts, I figured the custom enclosure was quickest.  Honestly, setting up for all the in process photos took about the same amount of time as actual assembly; and then add the loading of sound project and tuning/speed curve setup.