1. LOCOMOTIVE LIGHTING USING SURFACE MOUNT LEDs Jim Hinds RICHMOND CONTROLS

2. INTRODUCTION There are many ways to use surface mount LEDs to provide lighting functions in model railroad locomotives. This discussion covers illuminating headlights, signal lights, and ditch lights using the “603” size of surface mount LED, which measures approximately 0.060” x 0.030”.

3. WIRING CONFIGURATIONS

4. TERMINOLOGY In this discussion, the non-illuminated side of the LED where its contacts are located will be referred to as the “bottom”. The large light emitting surface on the opposite side will be referred to as the “face” or “top”. The term “mounting hole” is used to refer to any hole in the locomotive body shell or detail part meant to represent an empty light fixture, where an LED will be installed.

5. TERMINOLOGY

6. INTRODUCTION Installation generally requires a clear pliable adhesive and sealer, several drill bits, and highly opaque black paint. The mechanical LED mounting techniques are the same regardless of the type of power system and drive electronics used for the locomotive and its lights.

7. INTRODUCTION Several clear and pliable adhesives that also serve as sealers are available and recommended for this activity, including Pacer’s Formula 560 Canopy Glue and Micro-Scale Krystal Klear. Pactra Racing Finish black paint is a very effective and opaque black paint.

8. INTRODUCTION The user must insure that an appropriate current limiting resistor and any other appropriate protective components are used, PARTICULARLY if the LED is “white”. (“White” LEDs tend to be damaged more easily by voltage issues than non-white LEDs.)

9. INTRODUCTION Recommendations for electronic components for use with the LEDs can be found at www.richmondcontrols.com in the LED section. (All Richmond Controls modules have these components. Decoders generally have all necessary protective components.)

10. INTRODUCTION The selection of mounting arrangement for the LED is primarily determined by the geometry of the existing light opening and the ease with which factory-installed lighting components can be removed or modified. The installation approaches discussed are:

11. INTRODUCTION Mounting the LED’s face over an open light hole not containing a lens, Mounting the LED to the surface of a lens, Inserting the LED end-first into a hole, Inserting the LED face-first into a hole, Inserting the LED into a bezel and mounting this lighted bezel into a hole.

12. MOUNTING AN LED OVER AN OPEN LIGHT HOLE This approach is useful when the headlight holes are small and it is undesirable to modify them. Examples are the headlight holes in brass Z Scale and N Scale hood diesels. Simply glue the LED in position with the LED face over the hole. Example: AZL Z Scale C44-9W

13. MOUNTING AN LED OVER AN OPEN LIGHT HOLE

14. MOUNTING AN LED ON THE INSIDE SURFACE OF A LENS In some cases, the locomotive’s clear plastic lens cannot be removed gracefully, or it may be desirable to retain the lens. The LED’s face can be bonded to the inside surface of the lens. Example: Kato N Scale GS4

15. MOUNTING AN LED ON THE INSIDE SURFACE OF A LENS

16. A similar technique is to remove the backing from an MV lens that is somewhat larger than the headlight hole, insert the LED through the hole, glue the LED to the back of the lens, and then glue the lens to the front of the hole. Example: Kato HO Scale GP35

17. MOUNTING AN LED ON THE INSIDE SURFACE OF A LENS

18. INSERTING AN LED END-FIRST INTO A LIGHT HOLE An appreciable amount of light comes out of the LED’s ends. The LED will fit end- first into a #56 (0.046”) hole if its wires are configured to exit from one end of the LED, tucked against its bottom and insulated with a thin application of clear pliable adhesive. Example: Model Power N Scale RSD15

19. INSERTING AN LED END-FIRST INTO A LIGHT HOLE

20. Assuming the mounting hole is smaller than 0.046” after removing the stock lens assembly, use a #56 drill (0.046”) to drill from inside the shell to countersink the mounting holes. DO NOT LET THE DRILL BIT BREAK THROUGH TO THE FRONT SURFACE OF THE LOCOMOTIVE. Example: Intermountain N Scale SD45T-2

21. INSERTING AN LED END-FIRST INTO A LIGHT HOLE

22. INSERTING AN LED FACE-FIRST INTO A LIGHT HOLE This operation is the same as when inserting the LED end-first, except a #47 drill (0.078”) is used to countersink the light hole if space is available. This larger hole allows the entire LED to fit into the hole face-first. Example: Athearn HO Scale FP45

23. INSERTING AN LED FACE-FIRST INTO A LIGHT HOLE

24. If a #55 drill (0.052”) is used, the light emitting part of the LED will fit snugly into the hole, with the larger base outside the hole. Example: Athearn HO Scale C44-9W

25. INSERTING AN LED FACE-FIRST INTO A LIGHT HOLE

26. INSERTING THE LED INTO A BEZEL AND MOUNTING THIS LIGHTED BEZEL INTO A HEADLIGHT HOLE This technique is ideal for cab type locomotives in all scales, and hood type locomotives in the larger scales, where the headlight hole diameter is larger than about 0.075”. Example: Athearn HO Scale F7

27. USING A LIGHTED BEZEL

28. Another option is to countersink the back of the bezel as in technique #4. The LED can be permanently bonded inside the bezel, creating a “lighted bezel”, and then the lighted bezel can be installed in the locomotive’s mounting hole. Example: Kato N Scale F7

29. INSERTING AN LED END-FIRST INTO A BEZEL

30. FINAL STEPS Note that for each of these mounting methods, it is generally recommended that a clear pliable sealer should be applied over all exposed portions of the LED visible inside the locomotive. PACER’S FORMULA 560 CANOPY GLUE is ideal and strongly recommended.

31. FINAL STEPS The sealer should also be applied where it will wick between the LED and the inside surface of its mounting hole, to prevent the black paint applied later from being able to wick around to the front surface of the LED. After the sealer cures, an opaque black paint can be applied to control stray light, like Pactra BLACK Racing Finish.