Converting Atlas N-Scale RS-3 Locomotives to DCC

· Buy Atlas Locos

Since the writer is a neophyte, almost everything I say that’s important should be ascribed to other writers and people. Some are Aztec’s John, David Popp, Don Fiehmann, Debbie Ames of Lenz, Tony’s Train Exchange, and others I’ve probably forgotten. Atlas personnel have been invaluable in giving general assistance where possible, particularly in providing replacement for parts lost, avoiding any advice specifically aimed at DCC conversion. Modifications to Atlas products void their warranty, consequently, Atlas can’t advise on modifications of any sort. But, short of that, they provide extraordinarily patient support. One assumes that to be their normal operation. Any mistakes are mine.

There would be no DCC modification of the N-Scale Atlas RS-3 without a modification to the frame providing space for a small decoder. The Lenz LE0 511 series will fit in the space milled by Aztec Manufacturing (2701 Conestoga Drive, #113, Carson City, NV 89706). Mr. John’s directions, provided with your frame milled for a decoder, are good enough for the accomplished N-Scale mechanic. If you are doubtful regarding skills or determination necessary for the job, hire it done by someone like Tony’s Train Exchange.
For your information, Tony’s uses Aztec milled frames.

N-Scale DCC conversion of the Atlas RS-3 is practical, but it is easier if pitfalls not covered in literature are known with means of overcoming them at hand. With a little preparation the job is almost simple. Extraordinary patience is required, along with some experience in soldering in close quarters. You don’t have to be an electrical engineer, but understanding DC motors, decoder wiring, shorts, and open paths will be beneficial. Taking care in the disassembly will pay off in assembly. Bearing blocks have distinguishing features and should be assembled as they were delivered from Atlas. Bearing blocks have a smooth face and a face with a tiny hole. One edge is marked with striations. Disassembly should be carefully done as reassembly can result in noisy operation not anywhere equal to the quality of the locomotive. And, make sure you notice that the magnet painted white or silver is down in the assembly. The down brush will receive the orange decoder lead, or the locomotive will run backwards with the headlight burning at the trailing end.

The peculiar Atlas design approach not covered by other written material warrants discussion. Atlas uses a split frame design. Each half of the frame is isolated from the motor and from its mate by bushings between the frame halves. Those bushings are not a problem. If lost, like most small parts, they are not easily found. Keep track of them. One can’t make the assembly without the spacer bushings. The motor is suspended between the frame halves by black plastic suspension rings seated on the motor and properly clocked, the gudgeons on the ring engage slots in the frame castings. Properly seated and clocked on the motor, the suspension rings align the motor drive and electrically isolate the motor from the frame halves. Problems arise when the suspension rings come off their seats on either end of the motor just inside the flywheels. This is big. They must be replaced and properly clocked for the gudgeons to engage the slots in the frame halves. Don’t be deceived. The gudgeons are small, and so are the cavities in the frame. Reseating and clocking suspension rings can be a difficult job, but patience must prevail. The rings can be pushed into place with a fine bladed hobby knife I found that a piece of hard plywood about 1/32 thick will also make a fine assembly tool for suspension rings adrift. Slot a 3/32 wide piece just enough to pass the drive shaft and insert this spade device between the errant suspension ring and the brass fly wheel forcing the ring back on its seat. Then it can be clocked so that the gudgeons fit into the cavities in the frames. These parts are small, so one is advised to have a good lamp with a magnifying lens to do all this. When trial assembly shows that both rings are seated and gudgeons ready to slip into the recesses in the frames, carefully secure them with a small amount of cyanoacrylate. If the rings are already in place, secure the rings with a small drop of cyanoacrylate.

When you receive Aztecs frames, you’re ready for an important disassembly not done before. Pry the caps off the brush holder and take care with the brushes, springs, and caps. These parts are small and can get lost quite easily. They can be found after much regret is few over losing them in the first place. Springs can be handled by lifting on a wood toothpick inserted in the open end of the spring. The gray and orange decoder leads, trimmed to the length specified by Aztec, are soldered to the brush caps as suggested. Caps can be held in an oversized hole in a piece of scrap wood while both hands are engaged in holding the lead and the soldering iron. When the caps have the gray and orange lead soldered in place the fun begins. A spring is placed in the brush cap, the brush slipped into the brush holder, and the cap holding the spring inserted into the brush holder. Repeat this operation with the other brush and spin the armature by hand a few revolutions to seat the brushes. I don’t know if this does anything in seating the brushes, but it might, and that’s good enough reason to do it. Then one is ready to layout the bearings, worm gears, universal joints and motor assembly in the right hand half of the frame maintaining orientation of these parts noticed when disassembly was made. You didn’t notice when you took the locomotive apart? One noted authority advised assembly of blocks so that the smooth sides faced into the frame halves while the sides with the hole should face into the split between the frame halves. I took his advice and my locos run at the speed of what I imagine would match the unhurried pace of an N-Scale man.

Now, be sure the spacers are in the right hand frame half and bring the left hand frame over the assembly you’ve made. Of course, you remembered to replace the Bearing Retainers on the left hand frame. The spacers keep the two halves separated, and one makes the assembly workable by tightening screws against the hex nuts inserted in the left hand frame. Do not tighten fully yet. Soldering is best done with a hot, really hot, iron.. Good and hot, the iron quickly melts solder, heats wires and circuit board material quickly, and results in less damaging heat flow than forever holding a luke warm iron to the wires to be soldered. If you use the blue and white leads to drive the headlights, voltage to the light will see slightly less than track voltage, and the blue lead will have to be isolated from track voltage or any other lead. I see no particular advantage to using the blue lead, except that Lenz shows that as a correct option. I’ve found it easy to solder leads to the board mounted loosely to the frame assembly. You may prefer soldering the leads with the board on the worktable. Dress the orange lead so that it doesn’t put a load on the motor assembly. There is only one place to put the decoder, and lead lengths recommended by Aztec are set to the decoder being placed on the shelf milled for it. But, along with mounting the decoder on a piece double adhesive backed sponge mounting tape, Applying a coat of liquid electrical tape to the edge close to the leads soldered into the decoder is a good idea as long as it is sparingly applied. The location is close to a bearing block and worm gear. Check all soldering by visual examination, a multi-meter or both. Insert trucks, tighten the machine screws and take it to a test track. Programming an address should give a hint of correct wiring. Give it a run. If you’ve done your part, prepare to be amazed at how DCC operates v DC. Everything functional, install the body and enjoy.

You may be disappointed with the illumination of the headlight. If it detracts from your satisfaction with having converted to DCC, there is a sure fire fix. Miniatronics markets what they call a YELOGLO LED with appropriate limiting resisters. I don’t have to be paid to say that these LEDs are wonderful and give a most satisfying headlight. Pull the LED and limiting resistor from Head Light Unit 461104 and replace with the Miniatronics LED and resistor. Your track voltage may be good enough to provide you with a satisfying headlight and this step won’t be necessary.

We welcome comments or suggestions from readers; please write or call.