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Discussion Starter · #1 · (Edited)
Heres a guide for all dcc newbies out there who want to convert older Athearn locos to DCC. Please leave a comment on how helpful it was in the fourm aftewards.
Simple Guide for Converting Athearn “Blue Box” Locomotives to DCC

1.1 Preparation
First before starting make sure you have the following items:
Soldering Iron
Wire Stripers
DCC Decoder (of your choice)
Electrical tape
Small Screw

The motor must be Isolated from the frame and direct wheel contact so that the motor only takes power through the decoder which regulates it.
To do this first remove the metal clip touching the contacts on the motor and on the wheels. Discard this item because we will not be using it again.
Next take the motor off of the frame and take the metal tabs off being careful not to lose the motor brushes and spring. Next the tabs need to be swapped so that we no longer have contact with the frame. Also put a piece of electrical tape over the exposure of the frame.
1.2 Wiring
Make sure there is enough space between the decoder and the shell because the decoder may get hot enough to melt the shell plastic.Secondly comes the wiring, this step is essential to the wiring of DCC and if this is not done correctly you may short things out. Make sure you follow these directions carefully.
First you will need to make a spot to connect to the frame. Do this by drilling a small hole in the frame out of the way of the shell. Secondly put a small screw in the hole to solder to.
This is the tricky part. First solder the orange decoder wire to the top contact on the motor. Then solder the grey wire to the bottom contact on the motor. The red wire gets soldered to the back truck pickup and the black wire gets soldered to the frame screw pickup. Congratulations! You successfully wired the first half of the DCC decoder.

Next is the fun part. (Make sure when wiring the lights to put resistor on the lights!) The white wire gets connected to the head light. The yellow wire gets connected to the rear light. If you want to have ditch lights the green wire goes to the right light and the violet goes to the left light. (See my Ditch light installation guide to install your own ditch lights) Next the blue wire which is the lamp common gets hooked to all of the lights.

· Registered
1,483 Posts
ntrainlover, you forgot one tool, a hammer. So when you've lost all patience.........

Great job by the way.

One thing to remember. Those decoders get HOT!!! HOT!!! HOT!!! Be sure you have clearance for air flow and far enough away from the body as not to melt the plastic.

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49 Posts
WOW!! thats helpfull but i think i`ll need the hammer.

(ntrainlover, you forgot one tool, a hammer. So when you've lost all patience.........)(STATIONMASTER)

How bout if we all send our blue boxes to you and let you do them and pay you? Hmmm... sounds like a possible business venture huh?

Thakns for the info...

· Registered
241 Posts
This is great!!! Thanks for your contribution.

This will prompt my to install an Article system for the site, if it gets used.. You will also have to give us your real name at some point.
That would be a great idea, tworail!
I would be up to doing an articale on putting a decoder in the 2-6-0 I just finished. Really was dreading it, but once I got it started, really wasnt bad at all.
Also, I have 18yr+ in airbrush exp. would be willing to share also :thumbsup:


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527 Posts
I have put a DH123AT harness in a lot of older Athearns. It was not difficult...but not easy either. I like the quick-attach connections, but there is never really enough room under the shell for all that stuff. I found I had to get creative in cramming all that stuff under there. I haven't regretted it so far...DCC is sure nice.

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163 Posts
On YouTube, tommie022481 has some excellent videos on installing DCC into various HO diesel locomotives. His tutorials are well-thought out, clearly explaining the various steps necessary to install and program DCC decoders using Digitrax products.

10-30-2009 How to Install a Digitrax DCC Decoder into an Athearn SD40 - Part 1

11-03-2009 How to Install a Digitrax DCC Decoder into an Athearn SD40 - Part 2

11-04-2009 How to Install a Digitrax DCC Decoder into an Athearn SD40 - Part 3
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