DCC-signal is swithed off approx every 2 sec

wideko May 15, 2020

  1. wideko

    wideko New Member

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    L.S.
    At the moment I'm in a test-phase with DCC++ and JMRI. The goal is to test a few kinds of Current-Transformers.
    JMRI DecoderPro at the moment is 4.11.9 running at the PC with Win7. The Arduino is connected via USB to the PC. The Arduino does have a Chinese motorshield. The test from DCC++ for testing the enable, the DCC-signal and the LED's is fulfilled without problems.
    The locomotiv (HO) with a decoder from TAMS can be read and written in JMRI via DecoderPro. With the Trottle the locomotive can be started to run (after switching from program-output to main-output).

    The motorshield is now powered with 12Vdc/1A power-supply, enough in my case of testing the CT's (I think)

    BUT what I see is that the lamps at the loco are interrupted approx. every 2 seconds. The signal - measured after the CT - is also reduced to the current of only the load of the loco-decoder powered without running.

    Is this an issue in the DCC++ unit ... or ... should I look for problems with the decoder???
    (I have to dig in my cabinet to find another loco with a decoder)

    regards,
    Willie
     
  2. Atani

    Atani TrainBoard Member

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    The power supply is likely your problem, 12V supply will yield around 10V on the rails which is not sufficient for HO scale. If you can bump the power supply to around 15V it should work better.
     
  3. wideko

    wideko New Member

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    At the power-supply is written that it is 12V/1A. But today I've measured it and my Fluke TrueRMS is displaying 15.2Vdc.

    It doesn't look like a Brown-Out situation of the decoder, because the loco keeps on rolling at the testbank. There is no hick-up in the loco to be noticed. And even with the loco set at any speed, the lamps keep on blinking. It is as if the lamps are in ditching-mode? I will try the factory-reset and start over. .... Yes, it was something like ditching, now it is gone.
     
  4. Atani

    Atani TrainBoard Member

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    That is pretty interesting, not sure where the extra ~3VDC is coming from unless that supply has an adjustment/limit resistor that has been adjusted to allow higher voltage.

    I haven't seen a decoder do that before but it is good that you found a cause for it. If you have any info on this it might be useful to document it in the DCC++EX troubleshooting wiki page.
     
  5. RCMan

    RCMan TrainBoard Member

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    Does the power supply show "Regulated" or "UnRegulated.

    1 amp power supply "Unregulated" may not be stable enough.
     
  6. wideko

    wideko New Member

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    Nothing mentioned.
    It's a OEM AC-Adaptor Model-no: AD-121ABDT
    Power at:
    - No load (Track-power = OFF) 16Vdc - and 40mVac
    - Loco standing (Track-power = ON) 15.7Vdc
    - Loco head-light 15.4Vdc
    - Loco running 14.5Vdc


    It's not clear what caused the 'ditching', but after the reset it was gone.
    Some of my friends have tried to configure the decoder as well in JMRI-DecoderPro.
    The Decoder-XML we have made our self almost 2 years ago, because it was not available in JMRI at that moment. But I don't have that XML here at home :(
    Now I'm trying to get my XML-file in good shape and try to have every function in that file.
     
  7. wvgca

    wvgca TrainBoard Member

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    With that much variance, it's definitely an unregulated supply ... it probably won't show that ..
     
  8. Atani

    Atani TrainBoard Member

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    A quick google search shows that this is a generic wall-wart style power supply and likely it is an unregulated supply. Meaning as load/demand increases the voltage and/or current available will drop.
     

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