One of the last locos I bought came without a DCC decoder already installed. So, in my last order I included a Digitrax replacement decoder for it.
Since the loco it's an Atlas U25B I chose a Digitrax D163A0. There are few other type of decoder that are made specifically for that loco - from TCS and NCE if I remember correctly- but I thought the Digitrax is the best one and has a lot of features more than the others.
So, the last weekend I decided to start my first attempt at digitizing a loco. I was quite scared to damage the loco and the decoder in some way though I knew I had to try if I wanted to know how to do it and if I were able to do it.
The first step was to remove the shell and access the loco's splitted frame. The tank was pretty easy to remove but I had no idea on how to remove the shell. Then, I remembered articles, videos and photo on the internet where people started to remove the loco's cab first. So I begun to carefully remove the cab and after I unplugged the handrails from their holes in the cab it pulled out quite nicely.
The next step was the body shell. The rear side lifted very easily while the front side was a little more difficult. However pulling on the outside the walkway and handrails piece allowed the front of the shell to go up and been taken away. Finally, I removed the walkway from the split frame pulling it to the top o the loco.
At this point I had the factory installed PCB on top of the frame ready to be substituted by the snap-in decoder. To do that I loosen the two screws holding together the two frame halves and removed the PCB. This caused the two trucks to fall off the frame but that wasn't a real problem. It's very easy to put them in place.
Now it was the time to install the DCC board. Actually it was a little more difficult than expected since a had to be sure to put it into the right position and have the motor contact touching the corresponding contact pads on the board. However, I worked it out and put the two frame halves back together and tighten the screws. Don't forget to put the two trucks back in place before tightening the screws.
So, at this point the loco was ready for the very first test. I put it on the piece of flextrack I used for testing and selected the programming mode on my NCE PowerCab.
It worked at the first try. The PowerCab red the decoder type and version and the basic info correctly so I decided to exit the programming mode and try to operate the loco.
Headlights worked perfectly changing automatically from front to rear as changing the loco direction. Finally the most important test: running the loco. I increased the speed and it started moving perfectly slow and smooth. Everything was perfect, at least to me.
The loco moved very smoothly at very low speeds -it started crawling at speed-step 2 out of 128- and increased nicely up to full speed.
Last phase was mounting back the shell and all the remaining parts. It was a little easier to put all the pieces back now that I knew the correct order and how to do it. First the walkway then the body shell and last the cab. I put the handrails back into the cab's holes and that's it.
Now the loco was back on the test track for some more testing. I also reprogrammed few things in particular I added a small amount of momentum in order to have smoother speed transitions. The factory setting had no momentum set and wasn't very nice to see the loco stopping immediately when dropping the speed value suddenly to zero. I also changed the default short address 3 to the long 6702 corresponding to the loco's number.
Well, I'm very happy with the result of my first digitalization of a loco. Overall it wasn't that difficult mostly thanks to the use of a snap-in decoder that made the difficult part of the work very straightforward. A lease one point has to be improved, though. The front LED mounted on the DCC board is not shielded on the sides so the light emitted spreads into the whole cabin and not only through the headlight and number boards on the top front of the loco's cab. In fact the factory installed DC board has both the front and back LEDs covered with a black plastic film on the sides leaving only the tip of the LED free to emit light.
See you soon...
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