As requested, below is a tutorial on how to install a DCC decoder in an Atlas 4-4-0. Overall I think it is a pretty easy little project.
Estimated time: 1 hour
First of all, the 4-4-0 is a beautiful loco. A lot of great detail. The train runs great too. I would highly recommend this train for anyone looking for an 1800s era loco. Check out spookshow's page for more perfomance info. http://www.spookshow.net/loco/atlas440.html
I with with the TCS Z2 decoder. I chose this particular one because I saw that someone else had done it which gave me confidence and the fact that it is one of the smallest decoders on the market.
On with the show:
Here is the before shot.
For this lesson, the decoder is going to go in the tender on this train. One other note, I am not going to be wiring up the LED even though the decoder can control it. The wiring for the LED control is just not worth it in my opinion.
The first thing we are going to do is take off the tender cover. It may be tempting to just pry it off, but I would strongly urge against that. If you flip the train over, you can remove the first and last set of wheels on the tender. This will expose 4 tiny screws that hold the tender cover on. Remove these 4 screws.
Now that you have the tender top off, you can see the components. What we care about are the motor in the center, the two wieghts on either side and the little loop that is ate the back corners on the weights.
We now need to remove the two weights. They just slide right out. You may need to use a small flat head screwdriver to work it loose a bit. You will see the brass rods underneath the weights that transfer the track power. One weight carries the inside rail and one for the outside.
You will also see two long bare wires coming from the motor. These wires power the motor from the weights. The wires are just wedged in between the weights and the motor body.
The next thing to do is cut the bare wires going to the motor. You COULD solder the deoder wire to this, but it will make your wiring unnecessarily long and you will have a lot more insulating to do with. just remove them. The loco is now prepped for install.
Now it is time to get the Z2 decoder out. There are 7 wires on the decoder. Yellow, Black, Grey, Orange, Red, White and Blue. We only need 4 of these. I snipped out the wires I didn't need (unless you want to attempt the LED lighting) and I also cut the other wires a little shorter.
Yellow - Not used
Black - track power (will go in one of the loops on the weights)
Grey - motor power (will be soldered onto one of the motor connections)
Orange - motor power (will be soldered onto one of the motor connections)
Red - track power (will go in one of the loops on the weights)
White - not used
Blue - not used
I decided to solder up the motor first. Just remove the motor from the tender. Pay close attention to the rod and the little components with it so that you know how to put it back together. It's really not that hard or delicate. Sounds worse than it is. It does not matter with connection the black and grey wire is soldered to. You can simply reprogram the decoder later on if you have them reversed. Strip the wires, thread through the little ring and dab it with a bit of solder. It doesnt take much.
Now, this next part is something I learned the hard way.... You NEED to insulate these solder points. Once you put the motor back in the tender and the weights get wedged it, your motor will instantly get full DCC track power and it will take off at full speed. DOH!
To solve this, I simply put a strip of electrical tape around the solder points. A better way would be to use some Kapton tape, as its not a gooey and it has better thermo properties. I didn't have any, so I just used electrical tape and it worked fine.
The next thing to do is take your other two wires and just thread them through the loops on the weights. This is where Atlas was really friendly to us DCC people. You don't need to solder the wires if you dont want to. Trust me, once the tender cover is back on, everything will be locked in pretty tight and wont budge around.
(Sorry, I dont really have a close up picture of this one)
You might have noticed that I have some more electrical tape strips around the inside of my weights. I put this tape there before I realized about putting it around my solder joints. I think if you put electrical tapes on your connections to your motor, you are probably good to go. Any more tape and its overkill and you might have difficulty fitting everything back together due to the thickness of the tape.
Wiring is now complete!
Now we need to make some modifications to the tender cover. Here is when you can start branching off and doing whatever you want cosmetically. I would recommend, however, to reuse the tender cover in some form. The key is that the four screws that we removed not only told the tender cover on, but they squeeze everything tight inside and push those brass rods from the weights down under the tender where they get the track pickup.
What I did was take a dremel tool and cut out a spot roughly the shape of the decoder. Make sure not to cut through where the screws go. Once you get your train running fine, you can come back here and hide the decoder by putting a bigger load in the tender. A bigger coal pile or some wood will work. (I havent done this yet)
I just put some tape on it to protect the decoder for now.
Go ahead and put the screws and wheels back on and you are done! Easy as pie.
If everything worked properly, your train will show up as loco 3 on DCC control. You can follow TCS instructions on setting CV values as you wish.