MRC- LIMA Alco C420 (and/or similar) Electrical Diagrams

Model Railroader Electronics and DCC
1

I picked up one of those late 1980s-1990s MRC/Lima Alco C420 diesel RTRs a while back very cheaply. While missing some of the guardrails, it is unpainted and runs (DC) nicely as is. The lighting is the issue for me- it is wired with old-style larger bulbs (1/4" dia) for bi-directional lighting, which is weak at best. I want to LED it and run fiber optic strands into the dual vertical lights above the cabin and at the top of the rear hood. Has anyone come across a wiring diagram for this series of models- I tried the HO Seeker website but no luck and other general internet searches have not been helpful. Is there a quick shortcut to just “grafting on” an LED+resistor with wires to the wheel power assembly (and reverse wiring another one for opposite direction movement) without fiddling with the existing wiring- or has anyone come across electrical diagrams that might guide me?

Thanks for any help.

Cedarwoodron

2

For bulb to LED replacement in DC engines, I just replace the bulb with an LED with a 390 ohm resistor (each LED has its own resistor). LEDs are polarity sensitive, so they will be by nature directional. For the front, the long lead of the LED (positive) will go to the right rail, and the long lead of the LED will go to the left rail for the rear.

To assist in getting the LEDs to light quicker before the engine moves, I’ll install two jumpered bridge rectifiers in series with one of the motor leads. This means the motor won’t start to turn until it surpasses the 2.8 volt drop of the rectifiers, but is enough to light the LEDs before it begins to move.

Unless you have a habit of running your engines like slot cars, the 390 ohm resistor is plenty adequate.

Mark.