MRC 4-6-2 and 2-8-2 Sound Decoder Selection and RS-11 Install

[narrowminded]

For the negative side, any of the many green marked spots will work.  The green circles indicate large areas of copper on the circuit board which are the "ground" of the decoder.  If you want to attach your cap to those areas, you have to scrape off the green solder mask layer and expose the bare copper.

As far as red and black wires go, it is up to you, but in the DCC world red and green are colors are assigned to right and left track connections. You would not want to mix those up with the decoders internal ground and positive voltages.  That is why other color wires are used for the capacitors.  Blue is usually the internal positive voltage and black with white stripe is often used for internal ground.

The negative wire point of attachment I was referring to was the exposed solder joint, therefore no scraping to find a copper pad.  Is that OK or is there a reason not to do that.  

And thanks for those wire color suggestions.  I figured there was probably something that those in the industry would use as a "standard" but I didn't have a clue as to what it was.  I'm learning all sorts of stuff I never wanted to know.   

[RBrodzinsky]

I pulled this table together a while back, because it can get confusing (and note, after the Com+ column, things can get wild)
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[narrowminded]

I pulled this table together a while back, because it can get confusing (and note, after the Com+ column, things can get wild)

Thank you.  I put that in my printed out Loksound manual. 

[peteski]

The negative wire point of attachment I was referring to was the exposed solder joint, therefore no scraping to find a copper pad.  Is that OK or is there a reason not to do that.  

And thanks for those wire color suggestions.  I figured there was probably something that those in the industry would use as a "standard" but I didn't have a clue as to what it was.  I'm learning all sorts of stuff I never wanted to know. 

Yes, just as there are resistor color codes in electronics, some of the DCC connections have standard defined color codes.  Rick's chart is a good reference. Since I've been dealing with electronics as a hobby and on professional level for over 40 years I have memorized the resistor color codes and later also the standard DCC color codes.  And if you plan on DCC installs (or even just using DCC), knowing those color definitions comes in very handy.  So, you *DO* want to know them. 

As far as the ground connection on the decoder goes, all the green labeled pads and areas in my diagram are electrically connected, so any of them will for as a negative connection point for the stay-alive caps.

[jdcolombo]

Thanks John.  I do remember you mentioning the capacitor hookup last but I had forgotten about that.  Good I didn't already install them.  I'm pretty sure I won't need them on my layout but if I ever do run elsewhere or ever sell something, it'll be best to have them based on prevailing wisdom.  And who knows, I may find I actually do need them.   Does 200uf sound adequate for decent backup, the minimum if a soul was going to bother at all?  I know it can vary but at some point is it the job of the decoder install to cover for atrocious track conditions?

I've found that somewhere around 400uf is really necessary to make a serious dent in sound dropouts.  And that's not going to help with really dirty track - I'm talking about relatively clean track (and wheels) where you still get dropouts from truly momentary loss of electrical conductivity.  I keep my track and wheels pretty clean, but I noticed dropouts on my road units at slower speeds, particularly when traversing my yard ladder (which uses all powered frogs, so it isn't that).  So I put in two 220uf 16v tantalum caps, and that cured things.  It looks like you have room for caps on the shelf at the rear (or is that the front - can't tell) under the decoder.  These days, the preferred caps seem to be the polymer tantalum caps that are only 2mm high (they are more tolerant to over-voltage than standard tantalums); you can get 100uf, 20v ones, and I'll bet you have room for 4 on that shelf.  I'd put them in, even if you don't think you'll need them.

https://www.digikey.com/product-detail/en/panasonic-electronic-components/20TQC100MD2/P19854CT-ND/6202259

John C. 

[narrowminded]

I've found that somewhere around 400uf is really necessary to make a serious dent in sound dropouts.  And that's not going to help with really dirty track - I'm talking about relatively clean track (and wheels) where you still get dropouts from truly momentary loss of electrical conductivity.  I keep my track and wheels pretty clean, but I noticed dropouts on my road units at slower speeds, particularly when traversing my yard ladder (which uses all powered frogs, so it isn't that).  So I put in two 220uf 16v tantalum caps, and that cured things.  It looks like you have room for caps on the shelf at the rear (or is that the front - can't tell) under the decoder.  These days, the preferred caps seem to be the polymer tantalum caps that are only 2mm high (they are more tolerant to over-voltage than standard tantalums); you can get 100uf, 20v ones, and I'll bet you have room for 4 on that shelf.  I'd put them in, even if you don't think you'll need them.

https://www.digikey.com/product-detail/en/panasonic-electronic-components/20TQC100MD2/P19854CT-ND/6202259

John C.

They are the ones I mentioned getting.  I'm sure there will be space enough for several.

[RBrodzinsky]

I just started using these 20V 220uF AVX caps from Mouser https://www.mouser.com/ProductDetail/AVX/TCN4227M020R0100?qs=AQlKX63v8RuZx0wCV7zCew%3d%3d

[narrowminded]

Just checked SBS site and the Lokprogrammer is in.   Should ship today.  Also got a roll of black w/ white tracer wire for keep alive color coding.  I had already ordered the other colors.  

With this tool I hope not to enable the on board smoke generator.

[RBrodzinsky]

With this tool I hope not to enable the on board smoke generator.

Don't worry, that circuit is very robust and very difficult to disable. 

[narrowminded]

Don't worry, that circuit is very robust and very difficult to disable. 

No CV's required.  On board smoke generators are usually hardwired, aren't they?  

Now, depending on who you talk to, if it's the consumer calling the warranty guy, "It came from the factory that way".    And if you're talking to the warranty guy, vise versa.

[lashedup]

That's really superb work.  The speaker enclosure is ingenious; I wonder if it would fit other hood diesels besides the RS11.

Indeed, looks great.  Makes me wonder if we could 3D print an enclosure like that instead. 

[narrowminded]

Indeed, looks great.  Makes me wonder if we could 3D print an enclosure like that instead.

I imagine it could be printed but I don't think it will be all that universal to warrant the effort.  This was my first sound install so I'm not nearly as expert at what fits where as many of you are.  Over time I may find more applications for this exact one but from what little I've seen the dimensions are so specific to each model that I think the reality will be that many will look the same from a galloping horse but the few thousandths here and there that will be different will make it not lend itself to a universal design.  A standard set of approaches for different circumstances, yes.  But as far as a universal, one size fits many, I doubt it.  Now, if someone did the development for specific popular models and could find the volume...   

What might be able to be done would be a set of components that would readily glue up with each other but even then, experience says you'll forever be "so close but so far away ".   Maybe some more experience will point to a way but for now I'm not coming up with any specific, practical suggestions.

This could always be fabricated with some care for the dimensions.  I have the mill and also have a lot of professional experience designing and building specialty devices, regularly confronted with issues just like these, so machining it becomes my "easy way out".  But there would be many ways to skin this horse.  A knife, a square, some calipers, and some Evergreen is one that has worked for many.

[narrowminded]

Very nice indeed. Would you post a video when done?, would love to hear and see it.

"Ask and ye shall receive".  Or maybe better, "Be careful what you ask for." 

Programmer was on the porch when I got home today.  Finished setting it up and downloaded the Alco 251 file recommended by @jdcolombo.  Here it is, unedited.  May play with it tomorrow.  So far I'm pretty happy.

The video and sound is from my phone so the standard disclaimer applies.   And it does sound better in person and probably would come through better if it were recorded on better equipment.

[narrowminded]

And a final recheck of the speaker enclosure internal volume.  My initial roughed out plan, before I had the actual speakers in hand, had between 525 and 550 cu. mm and I was pretty happy with that based on the advice received.  As it was finalized I lost some of that because I had to move the speaker down into the enclosure slightly (about .020") to clear some board bottom components.  Final and pretty accurate is between 435 and 455 cu. mm.  The tolerance is because I don't really know the displacement of the speaker's mechanisms that are hidden behind the bottom fixed plate.  That's based on some pretty careful measurements in all other regards.

[jdcolombo]

Yep, that's the Alco 251.  Recognize that anywhere.

It does sound like there's a bit of distortion.  Not sure if that's the phone causing it, or the speaker.  If it sounds fine in person, leave it alone.  If you hear that "rough" sound when you blow the horn or ragged sound of the bell in person, then it's the speaker, and you might need to play with the volume control - turn it down some and see if the roughness goes away.

Otherwise, Thumbs Up!

John C.