Lighting Problem with DCC installation

Discussion in 'DCC & Electronics' started by Fluesheet, Oct 16, 2006.

  1. Fluesheet

    Fluesheet Member

    I need some electronics / DCC trouble shooting help.

    I am in the middle of a project to install a Tsunami sound decoder in a Heritage 0-6-0. The project has been going slowly, but with good success. My main issues to this point have been making things look tidy and planning for the future (firebox flicker / cab lighting). However, I ran into a problem today.

    I previously had installed an incandescent backup light which worked, but decided to switch to an LED to keep the heat down inside the tender shell (it's packed pretty tight). The problem is that after installation, the LED won't come on.

    The blue common is soldered directly to the LED, the function wire goes through a 680 ohm resistor prior to the LED.

    I did bend the LED leads around quite a bit to accomodate the location - could this have damaged the LED? The function lead itself seems to be OK as I am getting a reading of 10.74 volts prior to the resistor. The locomotive runs, the headlight / sound still work.

    What should I test / look for? I am unfamiliar with electronics to some degree and with LED's in particular, so I've attached a photo to illustrate where I am now.


    Attached Files:

  2. Fluesheet

    Fluesheet Member

    Found the problem. LED's are sensitive to polarity, and I had the above wired backward (function (yellow wire) to annode instead of cathod). Apparently I lost track of which was which when I had shortened both cathode and anode before marking which was which. I've now seen an LED light up in test, so I'm much happier now!

    A couple hours lost, but live and learn!
  3. Jim Krause

    Jim Krause Active Member

    sign1 Problem solved. Anything else we can help you with?sign1
  4. Fluesheet

    Fluesheet Member

    :D What would I have done without you guys?

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