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Problem with Train Lights
Joel asks readers for advice:
“I have just fitted a decoder to my locomotive and now the lights won’t work. What do I need to do?”
SUBMIT YOUR QUESTION
Not all decoders are the same when it comes to voltages for the lights. You have to know that the bulbs are rated for the decoder’s lamp voltages, or you might burn out the bulbs. Also, the Blue wire should be the lamp’s common (front and rear). White for the front light, and Yellow for the rear light. Read the decoder’s specs to be sure you match the lamps to the decoder properly. If using LED’s, then you must have current limiting resistors in series with the LED. In my experience, most decoders have about 13.5 VDC for the lamp supply. For an LED this would require a 1.3 kilo-ohm resistor (R=E/I) R=1.3k, E=13.5v I=.01amp. I do believe that a 12v bulb will work fine on the 13.5v from the decoder. Make sure your lights aren’t too bright, or they will probably burn out. Also, make sure that you are commanding the lights on, typically with F10.
I had the same issue with a Bachman DCC ready engine.
It will work but with what I have experienced so far the bulb will eventually burn out and quicker than under standard DC. Some resistance Should be added to keep from over exposing the bulb to higher voltage. Just as LEDs need the resistors, So does the standard bulb but I don’t know the value you will need. I have already burned out regular con-decent bulbs on some of my engines and I went a head and converted them to the LEDs with their resistors which are brighter anyway.
from Newman
If this is an 8 pin decoder double check it is plugged in the correct way round (ie orange wire to pin 1). If the decoder is fitted the wrong way round only the motor will run. Also if the decoder is hard wired as opposed to plug in the above comments are valid.
If possible, operate the “Lights On” control with the loco body removed, and test the voltage coming from the light output connections. Ensure your lamp voltage is compatible.
Also, LEDs must be connected with correct polarity (or no light).