# Installing Decoder in DC Locomotive



## DavefromMD (Jul 25, 2013)

Going to hardwire a decoder into a Walthers PH40 locomotive. One wire goes to motor+, the other to motor-. How do you tell which is the motor+ and motor- connection on the motor?


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## Brakeman Jake (Mar 8, 2009)

Motor+=orange,motor -=gray.


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## fcwilt (Sep 27, 2013)

Or temporarily connect the wires from the decoder to the motor.

Then with the shell still off and checking that no wires are shorted, test run the loco and see if the loco is facing in the desired direction when going "forward".


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## DavefromMD (Jul 25, 2013)

I guess I wasn't clear on what I was asking. I got the orange = +, grey = - part. What I was wondering was if there is a way to tell on the motor onto which pole the orange wire should go and which the grey should go.


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## fcwilt (Sep 27, 2013)

Yes - make the temp connections and verify that forward is "forward".


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## Brakeman Jake (Mar 8, 2009)

Right wheels +,left -.Motors are generally wired this way.


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## tr1 (Mar 9, 2013)

*NMRA standards will help in wireing*

orange wire, red wire, both are plus(+) black wire, gray wire are both negative(-).If I may
add. That is my understanding so far in researching DCC. Now, the NMRA standards sug-
gests, that the right side of rail(+) is supposed to be a red wire(+) and the left side of rail is a black wire(-). Some experts now claim to wire your layout for DCC, From the "get go".
I would think the wire motor lead wire locations would be in the directions. If not, trial and error should do nicely. Good luck. And regards, tr1


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## MrMoose (Dec 22, 2014)

Orange wire is the top of motor and gray is on the bottom of motor


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## Mark R. (Jan 26, 2013)

MrMoose said:


> Orange wire is the top of motor and gray is on the bottom of motor


Think about that statement for a moment .... if you rotate the motor 180 degrees top-to-bottom (not end-for-end) it still runs in the same direction, but now the gray wire is on top. 

You need to note which motor terminal is connected to the right hand rail (when looking forward) - that will be your orange wire.

If you do get it backwards, and don't want to re-do your wiring, just add 1 to the value in CV29 and it will correct itself.

Mark.


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## MrMoose (Dec 22, 2014)

Mark R. said:


> Think about that statement for a moment .... if you rotate the motor 180 degrees top-to-bottom (not end-for-end) it still runs in the same direction, but now the gray wire is on top.
> 
> You need to note which motor terminal is connected to the right hand rail (when looking forward) - that will be your orange wire.
> 
> ...


Why rotate it, just put it back in the same way you took it out. and alot of times the terminals on the motor won't let you rotate the motor or it won't go back with out clearance issues.


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## DonR (Oct 18, 2012)

When adding a decoder to a DC loco recently
I made the mistake of not marking the motor
orientation.

Thus I had a 50/50 chance of getting it wired wrong.
I lost.

Due to the unique chassis of that loco I elected
not to reverse the motor wires. Instead i reversed
the light board wires and then used my
DCC controller to tell the loco which way was
forward. (setting the CV). All is well and
the correct lights are on.

Moral: Mart the orientation of the motor before
you remove it.

Don


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## Mark R. (Jan 26, 2013)

I wasn't saying TO rotate it, I'm just making a point you need to note which wire went to which terminal on the motor BEFORE you tear it all apart. The orange wire isn't necessarily always the bottom terminal.

Mark.


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