# wiring question - NCE decoder into Aristo RDC



## JackM (Jul 29, 2008)

Phase Two is almost finished - adding 200 feet of track to the original 100 feet I did just in time for the first snow. Time to install the NCE D408SR decoder into my Aristo RDC. And suddenly all my self-taught electrical knowledge fades into the dust. I had all of a three-day weekend to ponder the problem, ended up figuring I'd call NCE today, then suddenly it's well after their business hours. Maybe someone (I KNOW someone) here can help me out. Not that I can't try a few things. I just don't want to do a smoke test on the motors, decoder, etc.

NCE instructions warn to make sure the motor brushes are insulated from the track pickups. Of course, the wheels are the track pickups. Something of a conundrum, I'd say.

Each motor has four wires: red, black, blue and...one has white, the other has green for the fourth wire. The decoder wires are red, black, orange and grey. I can easily conclude that I can simply snip off the connectors from the motors, get some spare wire to join the red and black wires from the two motors and the decoder plug wire and plug it into the decoder. Seems less than elegant, but sounds logical. Am I right, so far? Will this barbaric act properly isolate the "motor brushes from the pickups"?

But what about the two blues, one white and one green wires? I would guess, connect blue to blue, green to white (not much left) and make a random guess whether the blues should be connected to the orange or the grey. Not sure I want to plug it in, frankly.

Somehow I was expecting this to be a bit more "plug n play". Can someone help me out?

Bonus question for extra points: connecting the nine pin decoder connector to the 12 pin connector on the RDC: the triangle indicates pin #1, start there and ignore pins ten, eleven, and twelve, right?


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## Greg Elmassian (Jan 3, 2008)

The RDC has a socket. I'd solder some resistor leads to your wires and push the appropriate ones into the socket. 

When you remove the shorting plug from the RDC, it is DCC ready, and the track pickups are no longer shorted to the motor brushes. 

I see you found the connector, do you have a pin out of the socket? It will be really simple to do this. 

Regards, Greg


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## JackM (Jul 29, 2008)

The heavens have parted and showed me what I had not seen, then they slammed shut again. 

NCE calls it a dummy plug, so I hadn't noticed some of the pins were tied together (which makes it a shorting plug). I could just push the four wires from the motor/pickup connector into the first four spots of the RDC's 12-pin connector. But the second connector on the decoder has 9 wires, two of them "common". Aristo-Craft doesn't give any pinouts in the owner's manual, just says "the dummy plug must be removed and the DCC...plug inserted in its place". I suppose I can simply try plugging in 1 thru 9, and if that doesn't work, try 9 thru 1. That's tempting the Smoke gods, I fear. 

Sounds like I'll need to call Aristo and get a pinout of that 12-pin connector. And I'll call NCE; maybe the information's in the decoder manual if you hold it upside down in front of a mirror. I can't believe I'm the first to put an NCE decoder into an RDC. 

Thanks for your help, Greg. Without the pinout it's not going anywhere tonight.


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## George Schreyer (Jan 16, 2009)

The RDC is designed to accept a decoder in place of the dummy plug. NCE does not make one that fits so you'll have to wire it. 

see my RDC tips pages for a schematic of the loco and the pinouts of the plug. You should not have to cut ANY wires, but be aware that I had troubles with the headlights so I had to do some rewiring there. 

http://www.girr.org/girr/tips/tips9/rdc_tips.html


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## JackM (Jul 29, 2008)

George -

The NCE connection diagram merely labels its wires as "output1" thru "output 9", plus common. From your schematic I can see that the motor brush connections would go to pins 3 and 10, but without further labeling from NCE I don't know where the rest of 'em go. It shouldn't be this difficult. Will make some phone calls tomorrow.

Thanks for your info.


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## Greg Elmassian (Jan 3, 2008)

* http://www.aristocraft.com/techinfo/dcc%20rcc%20pin%20connectors/index.html* 


Try looking at that link, you can see which are track and which are motor, hook those up first. There are 2 pins on each "end" dedicated to track pickup...


You are probably looking at the wrong "end" of the NCE for the track and motor wires. Just connect the 4 wires (2 track, 2 motor) into the socket and see if it runs ok.


Your headlight and backup light may have to be rewired, read up on George's site.

Regards, Greg 


p.s. of course you could reserve that decoder for something else, buy a QSI, plug it in, lengthen the supplied speaker cable, plug that in and you are done with DCC, BEMF, sound and lots of goodies.


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## JackM (Jul 29, 2008)

What a coincidence! While Greg was typing his latest email, I found the Aristo site and the pin locations page and was able to piece together MOST of the puzzle.

If the color codes can be believed(!?!) - the pin number chart includes a column labeled "DCC Wire Color Code (Theoretical)" - which gives me all but three of the wire colors on the NCE decoder. I'm left with green, brown and violet, which are outputs 3, 4 & 5 (functions #1, 2, & 3 respectively). Back to the Aristo chart, the missing color codes are "Accessory color" for pins #5 and 8 and no color shown for "+ out". An asterisked note says 5 & 8 must be bridged for DCC.

In the function mapping section of the decoder manual, outputs 3 & 4 (violet & brown wires) are used for the left and right ditch lights, and output 2 (green wire) for mars light. From this I deduce that I want to connect the green wire to the + out pin #6 on the RDC connector and the violet and brown wires to pins 5 & 8, smoke/ditch lights. Other wire colors mentioned in the function mapping section match up with the color coding in the RDC chart so this seems to be the way to go.

Unless anyone has other information that might supercede all this.

Thanks, guys, for pointing me in the right direction. Now, as long as I don't see smoke.......

jack


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## Greg Elmassian (Jan 3, 2008)

Jack, I'm a bit concerned that there is some misunderstanding. 

This is NOT a DCC interface that maps all function outputs. The NCE decoder has a number of general purpose outputs, the Aristo does NOT have the corresponding inputs. 

There are no "functions" other than the headlight and backup light wired into the aristo socket. You keep talking about the function wires of the decoder. 

1. You CANNOT control the smoke unit directly from the NCE decoder, you will need to add a relay. 
2. Only the headlight and backup lights are in the Aristo connector. 

Please STOP and look at this project step by step. 

First, just get the motor and track hooked up, and verify. This will show you have power properly connected. Trying to "debug" an installation "all in one shot" is normally a mistake, even for someone experienced. 

Next you can TRY the headlight, but I suspect you may have a current issue... you need to check the current to make sure it does not exceed the decoder output. This will have you connecting a couple more wires. 

And NO, you cannot always depend on colors, so checking the pin numbers and the colors help. On NCE, I've not seen an issue, but Aristo "colors" cannot be depended on. A double check is always good. 

So: 

1. Hook up the 4 wires from the D408 to the appropriate socket "holes" and test for operation. 
2. Hook up the common and the head light wires from the D408 to the right sockets and test. 
3. if that works, hook up the rear headlight wire. 

Now, everything else needs a connection that is not on the Aristo socket, per se. 

Just go step by step. 

Regards, Greg


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## JackM (Jul 29, 2008)

Oy, such confusion!

Normally, I dislike taking something apart and putting it back together multiple times, but I suppose nothing says I have to put the body back on each time. I'll do each step as you suggest, and test with just the bottom plate on the motors. It'll look stupid running around the flowerbed half naked, but less chance of releasing the IC smoke that way.

And I might end up with that QSI after all.

jack


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## George Schreyer (Jan 16, 2009)

I would go with the QSI as it is a no-brainer plug in. If you want to spend less and NOT get sound, then use a Digitrax DG383AR. It is a straight plug in too but you might have to play with the headlights as I did. The stock headlights will work, they just won't be very bright.


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## Greg Elmassian (Jan 3, 2008)

Aren't you putting the decoder in the "box" directly under the Aristo socket? There is no reason to take the unit apart, at least so far. 

I think you are making this much more difficult than it needs to be. 

I think you should stop, use the D408 in another loco, drop the $145 for the QSI, plug it in and run. The only work you will need to do is lengthen the supplied speaker cable. You can fish it from the other "box" to the one where the decoder will plug in with a coathanger. 

I could install this for you in about 7 minutes, with no modifications to the RDC. 

Then you also have sound! 

Regards, Greg


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## JackM (Jul 29, 2008)

Speaking of making this more difficult than it needs to be:

I've gone through the list of available engine sounds on the QSI website and the Budd RDC isn't there. I think that's the reason I figured I'd use the 408 decoder that came with the NCE set. I believe Dalee (sp?) has RDC sound, so half a loaf might be better....

I think I'll back away from all this for a few days and see if I can figure out why my summer car is running hot in traffic. Nothing like some quality time with my cars to put things in perspective.


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## Greg Elmassian (Jan 3, 2008)

Yep, I have been using the GP40 sounds in mine, not perfect but sounds good until QSI gets the RDC sound... since you can update the QSI yourself (of course you need the programmer), it's not a concern to me. 

The comparison of the Dallee sound and the QSI is a Yugo to a Ferrari.... not even close. But whatever floats your boat... you will STILL be spending more money than a QSI. 

Use the 408 with a Phoenix... (but still more costly) 

Regards, Greg


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## JackM (Jul 29, 2008)

It's always good to take some time away from a problem, then come back and find the misapplied logic.

1 - The answers to my confusion were found on page 4 of the NCE 408 decoder instructions. If I have ditch lights, I would use the violet and brown wires; if I had a Mars light, I'd use the green wire, etc. I incorrectly assumed that those wires HAD to be connected somewhere (why else would they be provided?). Since I don't yet have ditch lights, etc., I had no need for such concerns and I now have an idea what they do. Yeah!

2 - The 408 decoder came as part of my NCE set, so it seemed reasonable to use it.

Instead I did, indeed, buy a QSI decoder, installed it in no time and was again discouraged that my system could not recognize the decoder on my Programming track. I later found in the NCE manual that a power booster is often needed for some decoders to be recognized. Well, jeez - I just spent over a grand for the system and I need to spend 50-60 more if I want to follow their own instructions.

So I skipped that stuff and put the RDC on my outdoor layout (won't need that hunk of track on the workbench) and it runs fine and sounds great! I am once again a happy camper. So thanks, guys, for your attempts to help.

Now - any suggestions what to do for a decoder/sound for my USA Trains Alco S4? The QSI website has almost no mention of USA. (NCE recommends their own 808 decoder.)

jack

You're right Greg, the GP40 sounds are close enough for govt. work til they come out with the real thing.


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## Greg Elmassian (Jan 3, 2008)

You would probably not need your booster on the programming track if you turned the lights off on the RDC. Try it sometime, but you can do everything you want programming on the main. 

Often sound cards draw more current than motor only decoders. 

I have used the QSIs since they came out, and I only tried one on a programming track a month ago, just for fun! 

My buddy RJ used his "free" D408 in an S4 too, and used a Phoenix. He had a 2k2, but you can use any one of them, since they are all DCC compatible. To make things simple, put a switch on each decoder to disable it, so you can have them both at the same address, but program separately. This will also help on the program track. 

You are in luck, I have documented just such an install on my site:
*http://www.elmassian.com/trains-mai...inmenu-228* 


The tricky things, the dropping resistors for the lights. 


Regards, Greg


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