Electronics and DCC

As most of you know, Atlas has offered some wonderful diesels models; some in our favorite railroad schemes. I model Seaboard Coast Line and the predecessors Atlantic Coast Line and Seaboard Air Line. Two of the Atlas offerings, EMD SD35 and its passenger sister, SDP35 were owned by SAL, ACL and acquired by SCL post merger. They are great models, but one major distinctive feature is missing. The SAL (and the one ACL ) SDP35 units were outfitted with a MARS light assembly between the number boards as shown below:

The clear GYRA light was used often when the locomotive was in passenger service or mainline express service. The red GYRA light could be used in an emergency or when stopped at a train station (passenger service). It was often used when a passenger train performed a backup move and the light noted the rear of the train ).

The following steps outline the modification to your Atlas unit; however these procedures may apply to other locomotive brands. Soldering experience, patience and a Opto-Visor are recommended. Have fun!

This sequence of photos outlines adding operating GYRA lights to a QSI OEM sound equipped SDP35 or SD35 locomotive.

Required Materials: TCS FL-4 function decoder; Ngineering micro Yellow-white LED 2-pack part number N1015-2; Tamiya Clear Red paint, part number X-27; Ngineering #38 Magnet Wire, part number N5038 or similar small gauge wire; Microscale Micro Kristal Kleer adhesive or Cool Chem Cyanopoxy system or similar clear drying adhesive; OPTIONAL: Miniatronics 2-pin micro mini connector, part number 50-001.

The directions pickup after the body shell and cab have been disassembled. The handrail ends attached to the cab can be hard to pullout; Try wetting the area around the mounting pin with Walther's Solvaset or Microscale MicroSol. The same goes for the numberboard/headlight assembly.

Separate number board into 3 parts

Cut the number board into three sections as shown with an Xacto snap saw.

Separate the lenses from the middle section.

Cut the headlight lenses from the middle section as shown. Note the size of the LED compared to the lens.

Attach LEDs to lenses with Micro Kristal Klear or Cyanopoxy.

Attach the LEDs to the lenses with Micro Kristal Klear from Microscale, Cyanopoxy, or similar adhesive. Do not use CA or Super Glue. When dry, paint the rear of the lens and the LED black to hide any areas that might bleed light. Paint the cut surface areas (inside edge)of the numberboards black.

Paint one lens red with Tamiya Clear Red acrylic paint.

Paint the remaining exposed area of ONE lens red using Tamiya CLEAR RED X-27 acrylic paint. Repeat 2 times. Allow each coat to dry before applying the next coat.

 

Install LEDs and number board halves in cab.

Install the LEDs and the numberboard halves into the cab assembly as shown above. To verify the lighting effect and to check for light bleed, you can apply power to each LED with a CR2032 watch battery. Add more BLACK paint to areas that bleed light. Secure parts with Kristal Kleer, Cyanopoxy, or similar adhesive.

Note: Install red lens in BOTTOM position.

On SEABOARD, Atlantic Coast Line and Seaboard Coast Line units the RED lamp is mounted in the lower position as shown.

Attach current limiting resistors and FL-4 decoder.

Attach the POSITIVE wires to the BLUE common decoder wire. Solder a 2.2K ohm 1/4 watt resistor to each NEGATIVE(Cathode)wire. Connect the other end of the clear lens LED resistor to the GREEN wire. Connect the remaining resistor lead to the PURPLE wire.

Splice decoder power leads into front truck harness.

Connect the Cab/LED/Decoder assembly to a DCC programmer and program the effects as follows:

CV35=0; CV36=0; CV37=64; CV38=128; CV51=34; CV52=34.

Program the loco's number into the decoder.

Locate the front truck wire harness. note which wire goes to the engineer's side. Cut the harness wires as shown and splice in the POWER wires from the FL-4 decoder. Connect the RED FL-4 power wire to the ENGINEER's side wire. Isolate the bare wire with heat-shrink tubing or BLACK vinyl tape. OPTIONAL: you can use a Miniatronics 2 pin micro mini connector set, part number 50-001, to connect the decoder to the front truck harness. This will allow total disconnection of the body from the chassis.

Secure the FL-4 to the inside of the locomotive shell, directly behind the cab on the inside of the roof with double sided tape or clear vinyl tape (not electrical tape). The clear vinyl tape from Ace Hardware is a great candidate. Reassemble the locomotive and test operation.

I hope you find this useful when upgrading your motive power unit requiring GYRA or MARS lights.

Happy Railroading!

Good stuff, Carl.   I'd like to see more of these types of threads posted by others in the future.

Tom

 Excellent presentation.  Any chance of a video clip to show them working?

duckdogger:

 Excellent presentation.  Any chance of a video clip to show them working?

I am currently between video recorders; I'll see if I can borrow one and make a video.

If you have a modern point and shoot, it might do video. 

NIce job on the tutorial, thanks for posting.  Those LED;s look really interesting.

 Carl,

A+ on your excellent step by step tutorial.   I have a P2K SD45 that I would like to apply your procedure on.

BTW: Please consider posting a picture of your unit with the finished gyra-lites illuminated. 

cmarchan:

Attach the POSITIVE wires to the BLUE common decoder wire. Solder a 2.2K ohm 1/4 watt resistor to each NEGATIVE(Cathode)wire. Connect the other end of the clear lens LED resistor to the GREEN wire. Connect the remaining resistor lead to the PURPLE wire.

I love the tutorial.

I was wondering if this is backwards?  I always thought the blue wire is the common and the negative side of the LED is attached to the blue.  The positive side is where the resistor and the function wire is supposed to go.  Am I right?

 Decoder functions (white wire, yellow wire, etc) are current sinks - the output transistor connects the wire to ground, so the function color are the negative lead in any sort of circuit where polarity matters. The blue wire is a common positive from the voltage regulator.

 It sounds backwards to a non-electronics person but there are several advantages to using current sinks with a positive common. First of all, for the same amount of current capacity, the sink uses a smaller transistor. Second, when the functions are current sinks, you can attach more than one function to the same circuit with no damage to the decoder. Say you wanted a red light that lights up when the train is in reverse OR flashes on demand by pressing a different function. You can hook the yellow lead to both the reverse light AND this read light, and also hook the F2 wire to the red light. So when you go in reverse, the red light goes on. Or when you activate F2, the red light flashes.

                                  --Randy

Thanks for the clarification.  I read the literature wrong that came with my TCS decoders.  I did install LEDs in a loco and everything turned out great.  It was a fairly easy project.

rrinker:

 Decoder functions (white wire, yellow wire, etc) are current sinks - the output transistor connects the wire to ground, so the function color are the negative lead in any sort of circuit where polarity matters. The blue wire is a common positive from the voltage regulator.

 It sounds backwards to a non-electronics person but there are several advantages to using current sinks with a positive common. First of all, for the same amount of current capacity, the sink uses a smaller transistor. Second, when the functions are current sinks, you can attach more than one function to the same circuit with no damage to the decoder. Say you wanted a red light that lights up when the train is in reverse OR flashes on demand by pressing a different function. You can hook the yellow lead to both the reverse light AND this read light, and also hook the F2 wire to the red light. So when you go in reverse, the red light goes on. Or when you activate F2, the red light flashes.

                                  --Randy

 

Well put Randy! You beat me to it; thanks for addendum