DCC Stuff
I recently bought a NCE Powerhouse Pro system and have been busy setting it up as well as installing decoders in my small locomotive fleet. Here is some of the things I have learned.
  • Athearn RDC installation - NCE D102EU

  • This install was my first and easiest, although I will tinker a bit more with the lighting. Prior to adding a DCC decoder I had completed a couple of modifications to the base Athearn RDC. I had added an Earnst regear kit to this RDC. Also I had hard wired the top brush to the power pick ups. Here are the steps I took to add a decoder to this unit.

    The installation of an NCE D102EU into an Athearn RDC is pretty easy
    1. Remember that I protect all wire to wire connections from shorts by covering with heat shrink tubing.
    2. Pop off the body and the motor.
    3. Apply a piece of black electrical tape on the chassis where the contact on the bottom of the motor usually picks up power. This is fundamental to all DCC installations. The motor must be electrically isolated from the track.
    4. Use double sided tape to mount the decoder onto the chassis.
    5. Since I left the one side of track power pickup connected through to the chassis, I drilled and tapped a hole for a 2-56 screw in the chassis.
    6. I used this screw to connect the trimmed red wire from the decoder to that power pickup.
    7. I trimmed and soldered the black wire from the decoder to the other side track power which was picked up off of the metal strip coming up from the nearby truck.
    8. Remove the brush straps from the motor so you don't melt any components on the motor when you solder the decoder connections on. Trim and solder the gray and orange wires from the decoder to the straps that hold the motor brushes in place.
    9. Since I don't have headlights on this model and this decoder has directional lighting, I used the light outputs for interior lighting. Since lighting is directional, I connected both white (front) and yellow (rear) light outputs to one lead of a Minitronics 50 milliamp 12 volt lamp. I connected the other lead to a 33 Ohm resistor to prevent the power on power surge from eventually causing decoder failure and then on to the blue wire from the decoder. This lighting system is just temporary, as I think a string of 2 or 3 lamps will give more even lighting throughout this RDC.
    I also had the starting from stop problem with this RDC as described in the F7 decoder installation. I eventually solved the problem with this RDC.
  • Athearn F7 installation - Lenz 103XF

  • I had a lot of trouble with my first Athearn F7 DCC installation blowing up 2 decoders along the way. I am not sure even now what caused the decoders to blow, but in both cases, I was fooling around trying to solve an operating problem that occurred after the installation. Before I describe the installation, I will elaborate on both of the problems.

    Athearn F7 with decoder installed, weight in rear
    1. The first problem manifested itself as a pronounced slowdown when making a right hand turn when going forward, or left hand when going backward. After much fooling around - and blowing a decoder, I discovered that the wires soldered to the metal upright on the rear truck were rubbing on the rear flywheel when turning right (going forward). I simply bent out the wires to avoid this contact to fix the problem.
    2. The second problem was reluctance of the locomotive to start from a standstill without a five fingered push, despite the fact that I could control the lights. I tried cleaning the wheels and track, but this only helped the problem a little. Being new to DCC, I was wondering whether the decoders just didn't have the juice to kick start one of these engines. Along the way, I blew another decoder. Finally, while experiencing the same problem with my RDC, I tried cleaning the commutators on the motor. At last these locomotives started working correctly.

    Most Athearn owners have hardwired power pickups directly
    Now the the high points of the decoder installation.
    1. Install two wires for decoder power from truck to truck. This is the standard tune up technique for Athearn. Instead of connecting the leads to the motor, use the leads only to connect the trucks together. Remember that with DCC, the motor must be electrically isolated from the tracks. I use a 100 watt soldering gun when soldering to anything like track, truck or metal fitting. A lower power soldering iron takes too long to heat up the metal, resulting in nearby plastic getting melted. When soldering any delicate electronic component on a circuit board, do use a lower wattage soldering iron. File any tarnish off the metal fittings, before soldering wire to it. The solder will not stick very well if you don't.
    2. Add a piece of black electric tape in the well where the motor would normally pick up power, in order to isolate it.

    Side view showing decoder mounted to the rear of the motor and lead weight above
    1. Deciding how to install the decoder into the F7 took quite a bit of calculating. Most Athearn DCC installations in literature and on the web apparently don't consider maintaining the super weight on the F7. It became obvious rather early on that I couldn't maintain the weight as it came from the factory. After much deliberation and calculating, I came up with this modification. I mount the decoder on a chopped down piece of the metal strip that was originally used for electrical pickup. This strip snaps on the top of the motor and the decoder is attached to this strip behind the motor with double sided foam tape. I reverse the weight with the protrusion facing forward. I have previously replaced the Athearn "CAB" lighting with 60 millivolt 1.5 volt grain of wheat lights glued to holes drilled in the headlights, so the protrusion doesn't interfere with any lights.

    Weight showing piece to be removed already cut and how additional L weight hangs on the rear
    1. I then cut the last upright off the super weight as shown in the photo. Then I cut some sheet lead to form an L shape piece that will fit in the rear end of the locomotive. The long part of the L is actually 4 thickness of this sheet lead taped together with electrical tape for extra weight. The top most piece of the sheet lead forms the little part of the L and the lip that hangs on the modified super weight. I file a notch in the top of the original weight for the sheet lead to rest on. If you don't file this notch, the body will not fit all the way onto the chassis. Put electrical tape anywhere you think a short to the decoder may occur.
    2. The rest of the installation is pretty straight forward. Connect the track connections from the decoder to the each side's electrical pickup. Motor connections are the same as shown in the RDC.
    3. Connect the forward light to the blue and white wire adding an appropriate voltage dropping resistor. Test on the programming track.
  • Proto 2000 SW9/1200 - Lenz 103XF

  • Although I initially had a lot of trouble with the Athearn F7 installation described elsewhere, as far as space goes, this has been my most challenging installation. This is another confirmation that I would be going nuts by now, if I had chosen to model N scale. As you can see, I replaced the diode lighting board with a Lenz 103XF decoder. There is very little room under the hood in this model for extra wiring, resistors or anything else. You could remove the weight and make things much simpler, but with my 3.5% grades, I need all the weight I can get. Things are so tight that I actually had second thoughts about taking the top off again in order to take this picture. Here is a list of things I had to do, to fit this decoder.

    The SW 9/1200 decoder installation was a bit of a challenge
    1. The original diode circuit board was popped lose and the wires to it were carefully desoldered. The mounting tabs for the circuit board were cut off and top surfaces of the mount were filed to a level even with the motor. The decoder was stuck on the top of the motor with double sided foam tape.
    2. The left side power pickup wires from front and back were carefully shortened so that they meet as close to the rear gear tower as was reasonable to do. I left just enough extra wire to allow a second chance should I have made some sort of mistake. The black power wire from the decoder was cut to loop back and meet the pickup wires. Then heat shrink tubing was placed over the wires and then the wires were soldered together. The same was done on the other side of the decoder with the right side wires. You can see how the red wires run in the gap under the edge of the decoder and the top/side of the motor in the picture. The heat shrink tubing was carefully shrunk around the wires with a lighter only after testing on the programming track was complete.
    3. The bottom wire from the motor was shortened and spliced with the gray motor wire from the decoder. The wires meet along the left side of the motor. If I was to do this over, I would have soldered the motor wire directly to the decoder as I did with the other motor wire. The orange motor wire was desoldered the from the decoder before trimming and connecting the other motor wire directly to this solder pad on the decoder.
    4. Before connecting the lights, I tested the basic decoder installation in this chassis. I carefully covered the ends of the lighting leads from the decoder with black electrical tape to prevent shorts while doing this testing.
    5. As you can see in the picture, the headlight is disconnected from the shell, and left to rest in the depression in the weight. One headlight lead was also directly soldered to the decoder circuit board. That is, the white headlight wire was desoldered from the decoder and then one lead from the headlight was soldered directly to that pad on the decoder. The yellow taillight wire was shortened and connected to one of the taillight leads. I left enough spare wire to allow the body to be removed or attached, but not so much that it would prevent mounting the body, altogether.
    6. The other light leads were each connected through a 150 ohm 1/4 watt resistor to the blue wire from the decoder. This is the resistor specified on Tony's Train Exchange web site. I think that perhaps 180 ohm or so might work OK, and run a bit cooler, but I didn't want to repeat this installation if the lights didn't turn out to bright enough. In any case, if you have a melt down or have another problem such as a burned out bulb, don't blame me. Do check out the section on this page that deals with dropping resistors for more information.
    7. The resistors were wired such that the two resistors were connected inline with each other. One end of the pair was connected to the taillight lead and the other to the headlight lead. The blue wire from the decoder was connected to the point in the center where two resistors were connected. Heat shrink tubing was added before soldering. The end result is a slim inline unit that can be squeezed in the gap between one edge of the decoder and the motor. This unit can be seen in the picture just below the bottom edge of the decoder.
    Wires running to the rear of this locomotive must be kept to a minimum. Although there are appears to be some room around the cab area/rear gear tower, too much stuff in there will keep the rear truck from swiveling freely or could rub on the rear flywheel.. My initial attempt at wiring the lights resulted in this problem and I had to shorten some wires. You might try pushing on the wires inside the rear of an assembled SW9/1200 with a long skinny object by poking it through the gaps in bottom of the rear truck, if you are having trouble.
  • Atlas RS3 - NCE DA102US

  • One thing to watch for is that many railroads ran RS3s long hood forward. If that is the case for your road, the instructions below will result in a backwards running loco. Switching the direction bit in CV29 will not move the headlight to the other end. If you want to run long hood forward, you will have to reverse the motor leads and the lights from front to rear. Reversing the connections to the track pickups, will have no effect.

    This has been my easiest installation so far. Follow directions exactly as written on the NCE decoder instructions. The motor connections will be on the opposite side from the original decoder board, but just run the wire from the bottom brush between the decoder and the motor to the correct side. Test for shorts between the motor connections and the power pickups with an ohm meter before trying it out on the programming track. I tested my installation and ran it before soldering the connections to make sure it was correctly connected. After soldering on the wires, I used the original connector caps to protect the connections from shorting against the weights at either end. Also I trimmed the strap coming up from the bottom brush a bit, so it wouldn't short against the decoder, which is mounted face down. The included bulbs appear to be 30 or 40 milliamps, so I didn't bother using a dropping resistor with this installation.

  • Decoder installations - Things to keep in mind
    1. Initially I had used the full length of wire as provided by the decoder manufacturers. This is not a good idea. Long wires add to electrical losses and increase the possibility of pinches, shorts, or rubbing.
    2. Use heat shrink tubing to protect your soldered wires from shorts. Remember to put the tubing on the wire before you solder the connections. I used a lighter to shrink this tubing in place. I was very careful to prevent damage to the model while doing this.
    3. If your model slows down mysteriously when making left or right hand turns, you should check to see if something attached to a truck may be rubbing on a flywheel when it swivels.
    4. If your model sometimes will not start from a stop without a gentle push, check for dirty track, wheels and commutators.
  • Calculating dropping resistor requirements - Bulb amperage

  • If you have a voltmeter and a variable DC power supply like I do, you can easily calculate approximate bulb amperage and the size of dropping resistor required for that bulb. What you do is connect an 100 ohm resistor to one terminal of the power supply, one lead from the bulb to the other terminal of the power supply. Now connect the remaining lead of the bulb to the remaining lead of the resistor. Now slowly turn up the voltage on the power supply until the bulb seems to be at the brightness that you want. If you know the rated voltage of the bulb, check the voltage between each lead of the bulb. You should be running at or less than rated voltage to ensure long bulb life. Now measure voltage between each lead of the resistor.

    Using Ohms law, you can compute amperage of the light bulb.
    I = V/R (current in amps = volts divided by resistance)

    Assuming 100 Ohms and say you see 10 Volts between the 2 leads of the resistor.
    I = 10/100 = .1 amps which is also known as 100 milliamps. (1000 milliamps = 1 amp).

    While you at it, measure the voltage between the leads on the bulb to determine an approximate rating, if you don't know it already.

    If the output from the decoder on your layout happens to be 14 volts and you have 1.5 volt bulbs, you can now calculate the size of the dropping resistor required for these bulbs.

    Using Ohms law:
    R=V/I (resistance = volts/current)

    Subtract the bulb voltage from the output voltage of the decoder to determine the voltage to use.
    R=(14-1.5)/.1 = 125 ohms

    In the case of the Proto 2000 SW9/1200 I used this method to help determine the requirements of the dropping resistor.
    I connected a 250 ohm resistor in the circuit with the bulb. I turned up the power supply until the brightness was about what it should be. I measured the output of the power supply at 19.56 volts and 18.35 volts across the resistor.

    The bulb would then have the difference of these two measurements between it's leads.
    bulb voltage = 19.56-18.35 = 1.21 volts. Lifelike probably uses a 1.5 volt bulb in this locomotive.

    The current through the bulb is the same as that through the resistor and can be determined by Ohms law.
    I = V/R = 18.35/250 = .0734 amps which is about 75 milliamps

    Finally to determine the dropping resistor required.
    R = (14-1.5)/.075 = 12.5/.075 = 166 ohms which is a bit more than the 150 I've installed in my SW9/1200. Perhaps I would have been slightly better off with the 180 ohm resistors I was thinking of using.

    To determine wattage requirements multiply volts times current.
    12.5 times .075 = .9375 watts. Those 1/4th watt resistors in my SW9/1200 are really not rated for the job they are doing, but I couldn't fit anything larger. No wonder they run so hot! Perhaps I should think of another way of doing this task.