Lighting Problem

Discussion in 'DCC & Electronics' started by Freelancer, Jul 9, 2004.

  1. Freelancer

    Freelancer Member

    I am kicking myself for joining the third gauge layout party because I am back at working on DCC and am having problems again. I am trying to add a head light to an engine with a DH123D Decoder. However I cannot seem to get it to work. The bulb is 12 Volts 50mA, the instructions suggest that anything that has a stronger pull then 50mA needs a 22 ohm 1/4 resistor. I first tried the light without the resistor, the light wouldn't work and for some odd reason the engine would start going backward. The throttle wasn't turned or anything. When I put the resistor on, the engine doesn't move unless I move the throttle, but the light still doesn't work. CV49 is set for a flashing forward light, on one decoder, I then tried a brand new decoder with factory settings and still no result. Does anyone have any ideas as to why this is happening?

  2. toopoor

    toopoor New Member

    You might of

    blown that bulb when you connected without the resistor. I've done it a thousand times. Try a new bulb.


  3. Freelancer

    Freelancer Member

    toopoor, I wish that was the answer, but the bulb works just fine when I connect it to the command station. Thanks for the inpute though!

  4. Freelancer

    Freelancer Member

    I brought in another engine with the same decoder and tested the light with the resistor but wasn't successful, I then took the resistor off and the light worked. I then tested the other two decoders in that engine and they both didn't workn with the light. However when I installed the decoder that worked in the other engine the light didn't work. I suppose that my next step is to rewire the first locomotive and see if that works.

    I was looking at the instructions again and like I said before it says that a 12 Volt light pulling over 50mA requires a 22 Ohm 1/4 watt resistor. I noticed that the pack of resistors I have says that they are 22k Ohm 1/4 watt. So my question is, what does the "k" stand for and does it make any difference? Also, since the instructions say if it pulls over 50mA then add a resistor, do you think it would be ok to not put a resistor in since this light is at 50mA and not higher?

    Thanks, Freelancer
  5. Fred_M

    Fred_M Guest

    There's one of your problems, the k stands for 1000, so you have 22,000 ohm resistors. Also check to make sure the decoder power from the "frame" side is good. Sounds almost like the decoder was running the motor power backwards through the bulb to power the motor. But without being there=who knows :D As to 50 ma question, (dirty harry voice) "do ya feel lucky?" It is a flip of the coin. :) Fred
  6. Freelancer

    Freelancer Member

    Well now I feel like a horses petute. :oops: Got rid of the resistor, maybe later I will find the right one. Put in a new decoder and resolderd the ground connection and the light works fine. Now programing it to do what I want is another story. :confused: Thanks for the clarification with the resistor dash.

    Thanks for all your help, Freelancer
  7. Matthyro

    Matthyro Will always be re-membered

    Something I have been struggling with too but putting the loco on the programming track and going through the programming steps got the lights working for me again. Not sure what I did but as long as the lights work it's fine
  8. Freelancer

    Freelancer Member

    LOL that is always how it is, don't know how I did it, but somehow I managed to get it to do something that I wanted, and I definitely couldn't do it again if my life depended on it. I think that programing the decoder is the worse part of the whole operation.


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