DCC and Lighting Upgrades

(James)

I recently completed an upgrade project with one of my locomotives.  When I say recently, I mean this morning.

Several weeks ago I acquired an Athearn F59PHI, in the Amtrak Cascades paint scheme.  This is a 2001 model, and so it did not come with Digital Command Control (DCC), or even as a "DCC Ready" model.  Seeing as I just got a DCC system up and running for my trains, I wanted to upgrade the model so it could be operated on DCC.  With "DCC Ready" models, there is usually a printed circuit board inside the model, with some sort of plug where a DCC decoder can easily be added.  The National Model Railroad Association (NMRA) has standardized DCC to some extent, and so most "DCC Ready" locomotives either come with an eight pin plug or a nine pin harness for the decoders.  It is quite simple to install them, as they only need to be plugged in and programmed and then everything is ready to go.

When a locomotive is not "DCC Ready," it can be a bit more involved to get a decoder inside it.  That is what this project was.  This was a very basic Athearn locomotive, with no wiring.  The electricity traveled from the trucks via metal tabs to the motor and the headlight.  The light and the motor were both grounded to the frame, which in turn was grounded through the trucks.  The headlight was simply a light bulb cradled in a metal post, bolted to the frame.  There really was not much to it, but it made the locomotive very simple and easy to work on.  Adding DCC required a few things though.  Since DCC requires all the electricity to be routed through a decoder, the motor and headlight would need to be electrically isolated from the frame of the locomotive.    Those metal tabs were removed, and electrical tape was placed along the frame, beneath the motor, so there would be something between it and the frame.  Leads were soldered from the decoder socket to the motor commutators and to the frame and trucks.  I chose to use a nine pin socket so I could remove the decoder if needed.  All the wires are color coded, and the color code is something else that is standardized by the NMRA.  That color code is the same regardless of who makes the decoder or the locomotive.

Once the motor was isolated from the frame and connected to the decoder harness, it was time to think about lighting.  This locomotive had one light bulb in it originally, which was on regardless of the direction the locomotive was going.  It lit the headlight and the cab windows.  I decided I wanted directional lighting, if nothing else.  Basically, when the locomotive would be moving forward, I wanted the headlights on, and in reverse I wanted the rear headlight on.  Since I had several headlights lying around from a different, simpler DCC upgrade, I decided to just use those.  As I was trying to figure out how to mount the headlights, I discovered that they fit perfectly into the holes that the light was supposed to shine through!  I figured putting a light bulb in each of those holes would be the easiest way to do it.  That's how they really do it anyway!  Since I was doing that, I figured adding marker lights, and programming them to operate in reverse, would not be that much more difficult.  I glued the headlights in place and then began wiring for that.  In all, seven light bulbs were added.  Two main headlights were placed in the center of the nose, and two ditch lights in the lower corners.  I also installed two red marker lights on the front of the locomotive, and a single headlight in the rear.

Once everything was in place, I tested it before I soldered anything.  The first good thing was that the locomotive moved in the right direction when I told it to do that.  Next was the lights.  I tested all the headlights and marker lights, and those seemed to work fine.  Since I had not actually programmed the decoder up to this point, the ditch lights acted a little funny, but they did operate.  Once all that check out, I programmed the decoder.  Since it was locomotive #468, that is the address it got.  I looked through the instructions on how to program the ditch lights to work with the headlights.  Once I got through that programming, they operated the way they should.  Once everything was programmed and operating as expected, I took the locomotive back to the workbench and soldered all the electrical connections.  I placed a bit of electrical tape over each connection to prevent short circuits inside the locomotive.

The next step was to put the locomotive back together.  This is a locomotive which once had no wiring in it at all.  After all that, there was quite a bit of wiring, and a decoder to cram in there.  It was getting pretty crowded!  That proved to be a bit more challenging than I had anticipated, but taping some of the excess wire in place did help.  Once everything had been reassembled, it was time for one more test, just to make sure I had not damaged anything as I was trying to cram it into the locomotive.  Everything worked.  To prevent light leaks, I added some putty for hanging posters around the back of the light bulbs, on the inside of the locomotive.  It was easy to install, and easy to form around the light bulb and seal the light out.

For anyone trying to upgrade a locomotive, here are a few reference items for you.
Red wire: Right (Engineer) side electrical pickup
Black wire: Left (Conductor/Fireman) side electrical pickup
Orange wire: This goes to the motor, where the right side pickup went.
Grey wire: This goes to the motor, where the left side pickup went.
Blue wire: Common wire for all lights.  If you use LED's, this goes to the positive side.  Make sure you install LED's correctly or they will not work.
White wire: This goes to the headlight.  If you use LED's, this goes to the negative side.
Yellow wire: This goes to the rear headlight.  If you use LED's, this goes to the negative side.  I also used it for wiring the marker lights, since I wanted them to come on in reverse.
Purple wire: This is a function wire.  Not all decoders have it.  If you are wiring ditch lights, wire this to the left side.  For LED ditch lights, this goes to the negative side of the LED.
Green wire: This is a function wire.  Not all decoders have it.  If you are wiring ditch lights, wire this to the right side.  For LED ditch lights, this goes to the negative side of the LED.

When you wire light bulbs, make sure you check the rated voltage and amperage.  You can operate 12 volt bulbs with no resistors, but there are also 1.5 volt bulbs out there and various LED's.  Light bulbs will explode if you let too much voltage through them, so make sure you use resistors if needed!  The amperage is also important, although the results are a little less drastic!  I used 30 milliamp, or 0.03 amp bulbs.  You want to watch these numbers so you do not fry a decoder.  They fry if there are too many amps.  Typically, on one function, you do not want more than 100 milliamps, or 0.1 amps.  In wiring my headlights, I had multiple light bulbs on each function, but I stayed under 100 milliamps.  On the white wire, I had two light bulbs, or 60 milliamps.  The green and purple wires both had one bulb, for 30 milliamps each.  The yellow wire had three lights on it.  The rear headlight and two marker lights were all on that one, for a total of 90 milliamps.  Make sure you are conscious of this so you do not overload your decoder.  The results could be fatal for it!

Now that the project is complete, I am a lot more aware of how DCC is wired.  I am by no means a professional, but it was a leap I had to take.  I was quite nervous about pulling apart a locomotive and rewiring everything.  It is not nearly as hard as I imagined it would be.  If you are nervous about taking the plunge and upgrading to DCC the hard way, I would recommend you start with an Athearn locomotive.  Since they are so basic and simple to start with, it makes life a lot easier when you go to upgrade.   They are very simple, and easy to understand, and they generally have a bit of space to work with inside them.  If it is the soldering that worries you, get some wire and practice a bit first.  It also helps if you have a 30 watt or less soldering iron and the thinnest solder you can find.  Another useful tool for troubleshooting is a multimeter.  It will tell you easily if you have isolated everything properly, and what is connected and what is not.  Once you do it once, you will not be nervous about it in the future.  Even on different locomotives, the principles are all the same, and you'll be able to do it again.

Programming can be a whole different beast, and we will cover that in a future installment.

For pictures of the project, check out our Facebook photo album.