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Dead to Death Pixels

Discussion in 'New Members Say Hello' started by Sam Stone, Feb 18, 2019.

  1. Sam Stone

    Sam Stone New Elf

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    I'm newly returning to seek help. Looking through the forums, I can't tell you how impressed I am with all the opportunities here. I am disabled, therefore poor, and in desperate need of assistance.

    The question: outside of obviously burned to death pixels, can I test 12V 12mm led pixels with ws2811 chips by the strand instead of having to cut each pixel out individually?
    The story: I spent 20 years last October - November building a 12V 8,000 led pixel matrix testing every 12mm 100 pixel strand as I went along. I used 400W power supplies and inserted at the beginning/end of each strand. Tested perfectly. I cut 6 foot 2 wire extension cords in half and use the male end for the strings and attach the female end to bring the juice from the PSU. After I finished a little showing off using X-Lights to prove it was awesome, I puffed out my chest and left it a few days basking in my glory. Two days later my son wanted to show it to his friends but didn't understand the male plugs were supposed to connect to the PSUs and plugged them directly into the wall. I came running when I smelled the smoke and unplugged the power strips as quickly as I could, but it was too late. My son is devastated and I love him for being proud, all the help he gave me building this thing, and just being a really great kid. In fact, I erroneously thought someone else made the mistake but that's an even longer story.
    The results: Several strings weren't connected and are fine. Others flicker, maybe one or two randomly spaced pixels light on a strand with no apparent consistency, some will come to life if I cut pixels out, etc, etc., but I can find no way to locate good and bad pixels without chopping the stands up, sometimes down to one pixel at a time. I'm getting the 12V at the end and random pixels light and random pixels don't when connected to the controller.
    Thoughts: Would it be possible to connect just the data cable to my Falcon V3 controller and run the pixels in front of a small store bought Tesla coil to identify the good ones? I've tried visual inspection and can weed out the obvious ones, but nothing else I do other than cutting and testing them one at a time seems to work consistently and I'm burning through fuses.
    Final: I very much want to turn this into a more positive result more for my son than anything else. If I had to, I guess I have the time to test thousands of pixels one at a time, but I also would like to learn. I've seen others who have similar problems on a thankfully smaller scale and to date have not found any solution.
    If anyone has any suggestions I would be extremely grateful.
     
  2. David_AVD

    David_AVD Bite my shiny metal ass! Community Project Designer Generous Elf

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    Hi Sam,
    If I read your post correctly, you used mains plugs and sockets for the pixel strings and they accidentally got plugged into 120V AC ?

    Assuming that's correct, I doubt any of those strings could be used in the future. Even if some of them still work now, they will likely fail before long.

    There's no easy way to test individual pixels while in circuit. Your idea of using a Tesla coil could only finish the poor things off.

    The importance of using the correct (and safe) plugs and wiring is the big take away here.
     
    Last edited: Feb 18, 2019
  3. lithgowlights

    lithgowlights Senior Elf

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    To be honest, using 120V plugs (and for us here in Australia 240V plugs) for anything other than 120/240V should never ever be considered. I personally don't even use extension cord cable for anything other than 240V, as that way I know what cables are what in my yard. While your son did make a mistake by plugging a 120v plug into the wall, ultimately it was your error in building it using mains plugs in the first place, so let this be the main thing that everyone learns from your accident - USE THE PROPER PLUGS.

    Now back to your issue, any pixel that was powered by 120V should be thrown away. If it's not dead now, it wont last long in the future so should never be trusted. Yes you might find some that work, but they have had over 10x their rated voltage (Actually the peak is more like 170v, so closer to 15 times their rated voltage), so the components have really been seriously stressed, and these pixels do occasionally fail and overheat, so by knowingly using these pixels you do really risk your display failing in a seriously bad way.
     
  4. battle79

    battle79 Full Time Elf Generous Elf

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    You could get yourself a bed of nails type alligator clip and use that to clamp onto the data cable before each pixel. This is assuming the ground and 12V still run through them all as original. Could make testing easier.
    That said I agree that all strands that got plugged into 120V would be highly likely to have issue after issue in the future.
     

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