Lights staying on after a show

Discussion in 'LOR DC' started by daunce, Dec 21, 2010.

  1. daunce

    daunce New Elf

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    After the show had finished for the night, i stuck my head out of the window, and noticed all 8 of my mini trees were still glowing.

    Using the hardware util, i turned all lights on/off but the mini trees were still glowing. It was more of 'glow in the dark' kind of light coming from the minitrees. With the hardware util, i couldn't fade the lights to give that same effect. And it was only that it was very dark that I could see the glow.

    I have a set of red lights, and they were completely off, it was only the green mini trees that were glowing. The minitrees are each on a different channel and have a common positive between all of them.

    I checked 4 hours later, and they were still glowing.

    Any ideas as to why there was still light coming from these ones? I recall people having similar issues with the AC boards, but didn't think it was an issue with DC boards.

    Cant recall seeing the glow any other night.. it did rain a fair bit last night...

    Using ~27v PSU, CMB16D-QC. All leds are from BigW this year.

    -daunce
     
  2. David_AVD

    David_AVD Good news, everyone!

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    Sounds like a slight leakage caused by wet wiring or boards. It doesn't take much at all to make LEDs glow visibly in total darkness.

    It could also be the controller. Next time you notice it, disconnect that channel's wire on the LOR board. Just the -ve one. If it goes off, the channel is leaky. If it stays on, the wiring must be wet.

    The only other thing I can think of is induction caused by running mains AC cables next to the LED wiring.
     
  3. OP
    OP
    daunce

    daunce New Elf

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    We haven't had much/any rain over the last few days, and the minitrees go off completely now. So it appears as it was definitely a water issue, but with no rain, i've been unable to do any further testing..
     
  4. darkeyrie

    darkeyrie Light-O-Rama User

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    Daunce,

    I have the same effect here and it is definitely water sitting in the lights. Easiest way to test - forget to turn the automatic sprinklers off and accidentally give the rig a soak :)

    We haven't had as much rain as the eastern states but we have had some here in Adelaide and that too caused it. I only noticed it mostly on the green and blue LEDs here which I hit with 36V.

    The main reason is that the DC boards are all "common positive" which means there is permanent voltage across the lights - with the faders working to raise the "negative" line up to the positive common voltage. This has the effect of turning off the lights as the voltage across each light drops to zero when their "common and positive leads" are at the same potential. The problem with this is when you create another leakage path to ground - which is why they start to light by themselves - e.g. get them wet and give the volts another place to flow to ground through.
     

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