Can I change out the LED's

Discussion in 'N / Z Scale Model Trains' started by KMInspector, Dec 7, 2007.

  1. KMInspector

    KMInspector New Member

    Hey all, I have a question about chaning out LED's. I recently had two UP Heritage units made for me and with those came the MRC sound decoder. All of my other locomotives have the digitrax decoders and they have a bright white LED, which in my opinion are more prototypical. The MRC has an LED that is very dim and has a blue tint or hue to it.

    My question is, can I change out those LED's to replicate or get closer to the brightness the Digitrax LED's have. Also, can this harm the decoder? I would really hate to sacrafice a sound decoder due to not liking the LED's but I am a stickler for details especially when it comes to getting my locomotives as close to prototypical as possible. Any help would surely be appreciative.

    Also I will try to add pictures of the difference in lighting between the two decoders.
  2. baldwinjl

    baldwinjl Member

    With the usual disclaimers, such as I'm sure once your soldering iron touches the board, any warranty is kaput, and that I don't have experience with that decoder, I don't think you should have any trouble. However, you might be disappointed. It is possible that the bigger difference is that MRC is limiting the current to a lower value, and that's part of the difference in the beightness. In which case, you'd need to change a resistor as well, and the task becomes much more challenging. I don't know that that is the case, but it is a possibility. I don't think damaging the decoder is likely, the current is still limited, and even if the LED forward voltage is a bit different, the limiting should still be safe, in my opinion.

    On the other hand, I'm not going to replace your decoder if I'm wrong!
  3. engineshop

    engineshop Member

    Don't unsolder the LED. Heat is really bad for a decoder board. Cut off the leads of the old LED as close as possible to the led. Attach small alligator clips to those leads so the act as heat sinks. Pre-solder the leads as well as the leads of your knew LED. Put the leads of the new LEDs on top of the old ones and (sandwiched with the alligator clips) and apply heat to the pre-soldered leads. It should only take a few seconds and you will noticed that the clips did not even get warm.
    LED usually are rated 3.5 - 5 V and I had never an replacement LED that burned out because the different rating but I also never changed a MRC board. You might want to call MRC and ask what voltage there LED is rated, just to be sure.

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