# Athearn blue box install



## buck71usa (Dec 27, 2011)

To help a fellow forum member out and possibly others i decided to do a post on installing DCC in an athearn blue box. I hope this helps some people out. Im installing a simple dh123d digitrax decoder in a Rock island sd 40-2 but the wiring schemematics are virtually the same for most decoders but not all! please chime in if im wrong.









First carefully remove the shell









Next remove the clip from the top of the motor and throw it in a spare parts box wont need it again unless u go back to DC









Next wiggle the motor out. note units with white motor mounts take a small screw driver and push from underneath (mental note be careful sometimes they are lil boogers to get out and you can push to hard and when it pops out you could stab yourself with the screw driver. trust me i did it on my first one! lol) If you have the black motor mounts just remove the 4 screws from the bottom.









Next you will see this shiny spot where the motor rested you will need to cut a small piece of electrical tape and place on this spot while being careful not to cover ur holes. this is done to isolate the motor from the chassis!









After that i always shorten the copper stripe coming from the light that way it cant come into contact with the flywheel.









Next you will see i went ahead and soldered a few points early to make latter work easier! Dont get to much heat on the copper stripe to the bulb or it can melt the bulb. ( soldered both truck tabs, lil copper strip for light, and some sodder for the metal piece that holds the light up!









On the bottom of the motor you will see 2 lil tabs sticking up. you will want to cut these as short as possible plus file a lil to smooth out.Next i add a lil solder to the top and bottom of the motor on the clips. Be careful not to get these copper strips to hot it can cause problems.Once i get solder on it i try to blow on it to cool it quickly( You can remove the clips from the motor to ensure better results but i dont because there are lil springs that they hold in and i always lose them! you do it how you feel comfortable with.)









Now i have attached the GREY wire to the bottom of the motor and the ORANGE to the top.( You will notice i have shortened the wires plus removed others that wont be needed for this install. Ones that i have determined I dont need i shorten allot but leave enough i can always reattach a wire to for a future change such as LEDs and things.) I just hate having to try and crame a ton of wires in something if I dont need them. You may want to leave them long for your install to attach the decoder to your shell or some other mounting point depending on your decoder and your preference. 









Next i have added a lil tape to the top off the motor and a piece to the side to hold a wire and protect the top from shorts.









I have re installed the motor with the help of a lil pressure and some wiggling









Now i have added a jumper wire between both trucks plus shortened and attached the RED wire to the front truck.( it doesn't matter which truck you mount the red wire to. I just used the discarded VIOLET wire for my jumper you can use what ever color you want!)









Next I attached my WHITE wire to the lil copper strip and my BLACK wire to the metal post.









Now i have cut a lil tape to bundle up the wires to keep them out of the flywheel and to make it easier to install the shell.









Plug in my decoder. By attaching the harness to top of the motor the decoder kind of hangs in the air. I do this because it seems to help keep them cool and there seems to be enough strength in the wire to hold it up away from the fly wheel. Depending on your decoder and Your preference you can do this how you wish. Have left my wires longer in other installs and 2 sided taped the decoders to the top of the truck or to the shell!









Put my shell back on being careful not to have any wires caught up and making sure the trucks are free.









Powered up and ready for programming!









I hope this helps some people out. im sure there are better ways and maybe even neater ways to do these installs and as I learn more I will find these ways out thats part of the fun for me! THX for reading. Paul


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## NSHO (Dec 28, 2011)

Thanks for your time and posting this tutorial. I've done a couple 123d installs myself and do exactly as you have done. I try to keep the wiring as short as possible but still allow movement from the trucks. The biggest problem I run into is after putting the shell back on, inevitably a wire or decoder rubs against the flywheels causing either a squeak or rubbing noise, which is amplified by the shell. I've taken the shells off many a times and repositioned a wire or a slipped decoder.


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## NIMT (Jan 6, 2011)

All in all a good install job.
There are just a couple of things I will note: The way you hooked up the head light is called "half hooking it up" It works ok but can lead to problems. The better way is to isolate the bulb or better yet replace it with an LED and use the (-)white wire and the (+) Blue wire to power the bulb or LED.
Wrapping the motor case to insulate it is not required on this model because the case is not connected to the frame or the power leads. It can also have a detrimental effect on making the motor run hotter.
Like you said soldering to the motor brush clips must be done fast and I would recommend if you don't remove them when soldering have a damp rag /towel/ sponge at the ready to cool it down. 
There is a lot better decoder style that makes it easier to keep the wires out of the flywheels, it called an AT board.








Soundtraxx makes them in both sound and non sound models.
You just stick a piece of double stick foam tape on the top brush lead and top of the motor and then stick the decoder on top of that. It keeps all the wires out of the flywheels.


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