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Decoder fitting to O gauge Atlas GP15-1


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Has anyone got a wiring diagram, or a how to video of fitting a sound decoder to this unit? It has two DCC sockets, one a 4 pin which has the pick up and motor wires...no problem with that, but the other is a 9 pin with 8 wires of various colours attached. 

 

This is is where I need the assistance...which wire goes where and as there are a few with the same colour, do they attach to the same place on the decoder?

C1116FC4-A969-4225-9EB0-CCB9CD84F972.jpeg

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  • Marmight changed the title to Decoder fitting to O gauge Atlas GP15-1

Dear Mar,

 

OK, first up, we need to clarify a starting position. Those shown in your pics (thankyou! :-) )
are certainly "plugs", but they are not "DCC Plugs". They do not match any known DCC-spec decoder connector.

 

Now, that said, a quick Google gave this reference to the very-similar Atlas dual-motor GP9.
While I'm not sure I'd advocate going "straight to series connection" without doing a lot of proper research first,
the thread does give some important clues to the internal wire-color-coding
(which, it must be noted, does NOT obey accepted NMRA DCC Internal wire color coding rules!)

 

https://ogrforum.ogaugerr.com/topic/wiring-an-atlas-o-gp-9-in-sequence

 

Happy Modelling,
Aim to Improve,
Prof Klyzlr

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A few chips from USA have a place for the JST 9 pin plug to go - this gives you the same colour outputs as you would normally expect for an 8 pin along with the extra function wire.

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...But AMJ,

 

The color-wires shown on the OP's "9 pin JST" pic in-and-of-themselves don't follow DCC convention,
which makes me leery that they are a "DCC decoder 9-pin JST compatible" loom...

 

...that the pics show the looms completely-removed from the loco
(woth no obvious evidence of previously-soldered/unsweated wire ends),

 

further shakes any confidence I might have had that the color coding can be trusted...

 

...The 4-wire loom arguably is the most "DCC logical", as the Black/Red (Track IN) and Orange/Grey (Motor Out) colors do make some sense in terms of providing "fundamental DCC decoder connectivity",
(IE appears to follow a fundamental part of the NMRA DCC decoder wiring color spec)
but that 4-pin Mini-Molex connector is not a NMRA-spec physical-format connector...

 

...and, given the GP15 has twin motors,
only having a single pair of Orange/Grey "Motor Out" wires doesn't match what we know about the model, leading to the conclusion that "the wiring required to match the known model config =/= normal DCC wiring connections or color coding"...

...the previously-linked "O Gauge Railroading Forum" post seems to support this hypothesis,
as it shows multiple pairs of Blue + Yellow being the "motor feedS",
which matches the multiple Light-Blue/Yellow wires on the "9 pin JST" loom...

 

In all, a rather "hard to discern out-of-context" collection of wire colors,
which, if I was in the OPs shoes,
(and I have an O2R MP GP15 salted away in the warehouse, so I guess I will be at some point in the future),

 

would provoke me to bail on the looms and ex-factory PCBs altogether,
and DIY the DCC-conversion wiring properly from the ground-up...

 

(I maybe see a NixTrainz "Decoder Buddy" in the OP's future???
https://nixtrainz.com/ )

 

Happy Modelling,
Aiming to Improve,
Prof Klyzlr

 

 

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Great comments in this thread!  :good:

A couple of thoughts based on my experiences with the Atlas dual-motor drive: I have ended up removing the Atlas board completely and starting over. I have had no issues running HO LS Select and now LS5 DCC decoders with the motors wired in series.  But my layout has no grades and I only need to pull 15 x 1lb cars max per loco.   You can use the Nix Trains Decoder Buddy as the Prof said with HO-sized 21-pin decoders in this case. 

 

With the motors wired in series series you will get lower power consumption, smoother running but slower overall speeds. But if one motor's truck loses traction it will spin up taking all the power and the loco will stop.    


if you have grades on your layout or need to pull longer trains then you would likely be better off leaving the motors wired in parallel. You will get more pulling power and a higher speed range, and if one motor's truck loses traction it won't stop the loco. But if you go this route I would got for a higher-current rating decoder such as the Loksound 5 DCC "L" to be safe.   

 

One issue you might have with the Atlas dual motor drive is starting off and very slow running. If there's a slight mismatch between the motors, the decoder may not be able to smooth them out perfectly at low speeds. Unfortunately the Atlas motors are low quality and have a lot of end float, plus there's quite a lot of backlash in the drivetrain gears.    
 
Here's a video of an Atlas dual-motor drive wired in series, speed matched and consisted with (but not coupled to) a single coreless motor drive for comparison. Both have LS5 DCC decoders. You'll see that the dual motor drive isn't as smooth first of all but cleans up after about speed step 3. Not too bad!

 

 

Pete

 

Edited by GP9u
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Wow...so much information, thank you very much. I’ll see if I can answer some of them.

 

 

Firstly, my apologies for not using the correct terminology. What I should have said is that Atlas state there are plugs and wires supplied for the owner to fit to the mother board once the blanking plate is removed from it.

 

the pictures show the 2 plugs as supplied and loose in the box by Atlas, they have not been removed from anything and are made by Atlas to convert the DC locomotive to DCC. 

 

After removing the blanking plate, two sockets, amongst other things become visible. One is a four pin socket, ideally for the 4 pin plug with Grey, Orange, Black and red wise attached, and the other, that has already been pointed out, a 9 pin JST socket, where the 9 pin 8 wired plug will fit. Now the 8 wires front this plug correspond to wiring that is DCC compliant and is for lighting and other functions regarding the same. The are what Atlas call DCC plugs for fitting to DCC sockets in the locomotive.

 

i can see no reason whatsoever why the 4 pin plug would not cover the track and motor functions as the wires correspond to DCC wiring, yes I know there are two motors involved, but the is a complete minefield of spaghetti wiring inside the locomotive. I fully understand the problems with non NRMA compliance regarding wiring colours, similar to the DCC not friendly Heljan double motored wiring...

 

From correspondence with other Atlas O gauge owners, I’m reliably informed that a decoder with a capability of up to 6 amps is required for this engine. I’ve plumped for a Zimo MX 699 Xl from yoochoos, who I have used for DCC supplies for a number of years without any problems.

 

The proof is in the pudding as they say, so watch this space and I shall report back.

 

Cheers

 

Martin

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45 minutes ago, Marmight said:

From correspondence with other Atlas O gauge owners, I’m reliably informed that a decoder with a capability of up to 6 amps is required for this engine.

6 Amps???!!!??? What are they trying to pull - real freight cars???

The 3Amp ESU Loksound L is perfectly adequate, for motors in parallel, and I have used a TCS HO 1amp Wowsound in my GP35 with motors in series.

As per others, I have removed the Atlas pcb & hardwired my decoders.

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It’s only what I’ve been told. I’d much rather put a heavy duty decoder in than watch the little puff of white smoke and black holes appearing on components where black holes shouldn’t be...

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Saturday morning update...

 

Ok, with some trepidation, I pulled off the blanking plate inside the engine. You have no need to take the body off this one as the middle section of the roof clips on and is easy to remove in a Dapol 08 fashion.

Looking at the motherboard and after moving the birds nest of wiring for both motors, the two sockets we are concerned with are both marked DCC.

So, taking the 4 pin plug, I connected the wires in true DCC fashion to the decoder...red, black,grey and orange and plugged the plug into its socket on the mother board. I also connected the large bass speaker to the appropriate places on the decoder.

Placing the engine on the rails, I powered up the controller, so far so good. Punched in 3 for the address, no visible signs of a burn out, pressed 1 and the bell rang...pressed 8 and the engine started...pressed another number that I can’t remember and the horn sounded...phew!

Turned the throttle on the engine started moving slowly, gradually picking up speed until it ran out of my 1 yard of test track....

Major Whoopee!

Well the colour codes for the wiring are to DCC standards, and both motors turn equally.

 

The big question now is where do the eight wires from the other jst plug go to on the decoder? Can someone please tell me which colour relates to what terminal on the decoder.

 

TIA and for everyone’s input into this topic.

 

Cheers

 

Martin

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Sunday update...

 

Going from the 9 pin 8 wire JST plug and socket

 

Well, everything I’ve seen and trued to find out points to the blue wire being the + in wire, and the yellow and white wires are the headlights/tail lights.

so, connect to blue wire to the correct terminal, it says + input...

connect the yellow wire to the correct terminal...it says headlight front, and the white wire to the next terminal, which says headlight rear. Power up and the cab end lights come on when forward is selected on the controller. Change the direction and the cab end lights go out and the red tail lights come on...which is exactly what I expect.

 

Now the wires that are left are, green, another yellow and white wires, a black wire and an orange wire. 

Connecting the second yellow wire to the terminal marked F1 and pressing F1 on the controller brings the rear headlights on permanently as long as the F1 button remains pressed. Pressing F1 again turns the light off. It doesn’t matter which direction the loco is operated in, F1 light remains on and does not go off nor the red lights at the rear come on.

So, I would have thought that connecting the other two white and yellow wires to the opposite terminals where the first wires are connected. I E terminal front headlight has a yellow and white wire, while terminal 2 rear headlights also has a white and yellow wire if you get my drift. 

Trying all sorts of configurations make no difference.So at present, if I set the direction to forward and have F0 switched on, the cab headlights turn on. Switching direction to reverse, the cab headlights go out and the red tail lights come one, which is expected. Unless F1 is pressed, at no time do the lights at the opposite end to the cab lights work.

 

I’m going wrong somewhere and it’s probably very simple...any ideas?

 

btw, the engine runs super smooth at very low and prototypical speeds.

Edited by Marmight
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This is where what Prof. Klyzir said earlier is borne out - that 8/9 pin socket is not wired to DCC colour codes; a DCC version would carry the orange, grey, red & black leads as well as a blue and one each of white & yellow. The other is green IIRC.

So as this socket doesn't follow the normal conventions and as most of us here start from scratch we aren't much help it seems. Throw in the fact that US locos don't really use red rear marker lights generally, except in a few rare circumstances - I for one remove them from my locos, but I'm not worried about keeping them 'original' or any re-sale value.

Maybe the group who reliably informed you about needing a 6 Amp decoder as a minimum can help?

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Thanks for the reply.

I think we are at cross purposes here, I’ve never said the wiring confirmed to normal practice and it has been pointed out before in this thread that early American so called ‘DCC ready’ locos used a similar set up. The four pin plug containing grey, orange, red and black wires are to the same format as DCC. It’s a totally different plug but the wires do the same job as on any other DCC setup, ie pickups and motor. That side of if is working wonderfully well.

The JST plug and 8 wires is the one I’m enquiring about. Here we have two yellow, two white, one green, one blue and one orange wire. Now according to every DCC wiring diagram I’ve seen, blue is the +common feed, yellow and white are head and tail lights using F0 and F1. So up to now, apart from the plugs and sockets they fit into, everything has the same designation and colour code as any other normal DCC wiring setup.

As you say regarding the red lights, they are not used any more, then I can happily live with the current set up and disregard the excess wiring, which might be on the plug for different attributes that my engine doesn’t have.

 

I didn’t get the information from any other group, but from someone in the UK who has a few older Atlas engines. I have also spoken to a personal friend who works for the importer of Zimo decoders for the UK and he has told me the same. I also seem  to recall, although I can’t find the page now, that Atlas themselves rate the stall settings of this engine as being a lot higher than modern day counterpart motors. That reinforced my decision to use a heavy duty decoder, and it’s one that I regard as being a safe decision, irrespective of how many cars it will pull.

 

As I have previously stated, the American side of things is new to me, but I’m learning fast. 

 

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That's good you found the Blue wire is the +ve for Function/Aux outputs.  That's NMRA spec at least.  ;)

 

Now I think you have 2 sets of variables:  

  1. Physical: What each of the other wires on that plug are connected to in the loco
  2. Logical: How the Zimo Function/Aux output effects and Function Map are set up (not sure what Zimo calls them)

For 1, you could solve by connecting the Blue wire to the +ve Function terminal. Than you could try each of the other wires on the plug one by one connected to the Zimo F1 terminal, see if any other lights come on in the loco when you turn on F1, and note that.  Once you know what they all do, you can choose to have any or all of them work on various Function outputs from the decoder.           

 

For 2, the convention for NA Diesel sound files among most decoder manufacturers for headlight is: 

F0F = White wire = front headlight

F0R = Yellow wire = rear headlight

 

Then with F0 on, the F&R headlights would be directional by default, but that can be changed in the decoder Function map of course. 

Maybe your loco was set to run long hood forward, so white is the front?

 

Usually F1 is assigned to bell (latching), and F2 to horn (momentary) by default.  But it seems Zimo has F1 mapped to a Function/Aux output so maybe they don't follow that F0F and F0R convention.  

 

Would you be able to share the default (or current settings) for the  Zimo Function/Aux output effects and Function map table? 

 

That should make it a bit easier get it set up how you want once you know what each of the plug wires are connected to.

 

Pete

 

  

 

  

 

 

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Quick update:  Looks like Zimo MX 699 series does support F0F and F0R but it's called HLf  and HLr.

 

So if you connect the white wire that powers the front headlights to HLf and the yellow that powers the rear to HLr , you should get directional headlights that can also be turned on and off together with F0. 

 

Caveats: The F and R might be the other way around if your loco was set up to run long hood forward.  The directional effect depends on Zimo Function settings. 

 

Pete

  

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Wow, many many thanks PeteM, just the information I was looking for.

i will try this out in a couple of days and report back on the forum.

 

Incidentally, I’ve found out that NEC produced a decoder ref: D408SR which uses the same twin plug configuration for DCC , 4 pin for pickup and motors and 9 pin for lighting and other ancillaries as is fitted to this locomotive. Unfortunately the wiring for the 9 pin plug doesn’t correspond with the wiring in my loco, although the four pin wiring is the same and DCC compliant.

7D7CD977-4EDE-454D-A2EE-6842FE98EC91.jpeg

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:good:

 

I used to use those NCE D408SRs with Soundtraxx DSX piggybacked before I went to Loksound a few years back. That NCE plug had 2 x Blue +ve, the white F0F,  yellow F0R and green Aux 1.  I think purple for Aux 2, and then maybe brown and some stripey ones for the higher Aux output -ves.

 

Anyhoo, you're on the right track now...  ;)

 

Pete

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Hurrah!

 

Thank you Pete M for steering me in the right direction, which is not the way the engine faces...

 

So, I connected one white wire to F0f and one yellow wire to F0r...lights came on and off as I changed directions but not the way it’s supposed to.

 

So, connected the two white wires to F0f and the two yellow wires to F0r...Hurrah, directional lights, but...

 

Set the engine to go forward and the long rear end, is that called the hood end? goes the wrong way for the lights, vice versa with the opposite direction. I E, the red lights at the cab end are off and the main light at the same end is on...no lights at the other end, which is the way the engine is heading.

Scratch head for at least 5 seconds...connect the Yellow wires to F0f and the white wires to F0r...lights on and in the direction of travel, and they change when the direction is reversed. The only problem is the red lights at the long end don’t work...but I can live with that!

The only wires that do anything are the blue and both yellow and white wires. The rest are superfluous and are tucked out of the way. I suspect the are for different lights, such as ditch lights, strobe, mars or flashing lights.

The mapping of the decoder shows F3 = bell, F4 = Shunt or half power mode, F7 = Horn (which I love to bits) and finally F8, which is engine start.

There is not a lot, but I really consider other sounds on decoders to be a waste of time. As it stands, it has everything I want.

 

Now there is a Weaver GP38-2 to be converted...I’ll be back (in my best Arnie

 voice)

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A post script to this...

 

From Model Railroader for March 2007

 

“The Trainman GP15 isn't available in a DCC-equipped version, but a decoder can be installed. The model includes a removable secondary printed-circuit (PC) board, two plugs with color-coded wires that follow NMRA Recommended Practice 9.1.1, and a separate instruction sheet describing how to connect those plugs to the main PC board and a heavy-duty (6 amp) decoder.”

 

Recommended Practice Section 1.1

 

S-9.1.1.1 Six and eight pin Interface

S-9.1.1.2 JST 9 Interface

S-9.1.1.3   21MTC Interface  

S-9.1.1.4 PluX Interface  

S-9.1.1.5    Next18 Interface
 

 

Recommended practice 9.1.1 states...

 

Table 3.1 Interface Wire Color Codes COLOR FUNCTION RED right-hand rail power pick-up (center rail, outside third rail, traction/overhead wire) to motor or interface ORANGE interface to motor (+)1 BLACK left-hand rail power pick-up to motor or interface GRAY interface to motor (-)2 WHITE output 1 front headlight(s) YELLOW output 2 rear headlight(s) BROWN or VIOLET3 speaker + and - GREEN output 3 (Aux 1) BROWN or VIOLET3 output 4 (Aux 2)

output 5 (Aux 3)
output 6 (Aux 4)

output 7 (Aux 5)
output 8 (Aux 6) BLUE common (+) headlight(s)/output(s) power source BLACK/WHITE STRIPE5 common (-) power sink or decoder ground.

 

I think my choice of a decoder that can handle 6 Amps and upwards was fully justified.

I also think that the wiring and plug set up in the loco is compliant with NMRA DCC practices.

 

A huge thank you to everyone who helped in this matter.

 

Cheers

 

Martin

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Quote

I also think that the wiring and plug set up in the loco is compliant with NMRA DCC practices.

 

(Prof tries very hard to stop slamming his head against a wall)

 

 

Edited by Prof Klyzlr
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Hi Hey, I’m just copying what the NRMA directive states...

 

as for banging heads against a wall...join my club, you’d be very welcome lol.

 

Anyway, we got there in the end and thanks to all your help.

 

Cheers

 

Martin

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Not arguing with your choice of a 6Amp decoder, it's 'belts & braces' and certainly no fear of the 'magic smoke release', but I'd be very interested to know what amps the loco actually uses in service, if you have a way of finding out? (such as NCE Powercab).

Back in 2007 I don't think there was a 3Amp decoder available; it was "all or nothing" - 1Amp for HO or 6Amp for 'big' stuff; clearly 1Amp is no good for parallel-wired twin motors, so 6Amp it would have to be.

I run my Atlas O SW1200RS, which is a single motor, with a 1Amp Tsunami decoder. It draws about 0.75Amps at full speed. There wouldn't be space for a high-amps decoder. My GP35 with twin motors in series uses a TCS 1Amp Wowsound, with simar power consumption. 

I have a QSI decoder that was factory-fitted by Atlas in an F3. I will have to see what Amps that is.

 

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The article in Model Railroading was a review on this particular engine. I have no way of testing for the actual amps, but they did publish this chart which shows their findings.

 

There is no arguments, I really appreciate everyone’s comments.

 

Cheers

 

Martin

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That chart bears out my experience.  I wire the motors in series which roughly halves the current draw. I make sure my locos always get to wheel slip before stalling. FWIW I've never seen more than 1A per loco on my RRAmpmeters in use when wired in series. But as noted prior, I have no grades and only need to pull max 15 x 1lb cars per loco.


l prefer to take the risk with "HO-sized-and current-rated" decoders because I want to cram the largest possible Tang Band speakers in the shell. But that's just me. Fortunately I've never had an LS Select or 5DCC HO-sized decoder fail in use with my Atlas dual motor drives. 

 

I suspect there's no such thing as too much decoder current capacity, so it's horses for courses and each to his/her own!          ;)

 

Onward!

 

Pete 

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