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Thread: Injected pixels instantly light up bright white when plugged in with pc power supply

  1. #21
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    Default Re: Injected pixels instantly light up bright white when plugged in with pc power sup

    Hi, @ MartinMuller2003.
    The data line is regenerated at every pixel and is "With Respect to" the ground at the pixel generating the data.
    You are correct. If I may offer another variable to consider, given that the pixels use PWM to control the light output of the LEDs the load on V+ and ground can vary significantly when viewed momentarily and the load can be specific to a particular part of a string dependant to the sequence. This can be even more complicated by differences in the specific light output of each pixel and the PWM that it runs in comparison to its neighbours.

    Most faults with regard to injection manifest in pixels working when in test – red then blue then green works and white fails. The follow up to that is to add injection and this mostly cures the problem but if the injection is boarder line this can still result in random spot errors when the PWM of a group of pixels combines to load and unload the power lines as data is being passed.

  2. #22
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    Default Re: Injected pixels instantly light up bright white when plugged in with pc power sup

    Thanks. The Permutations are almost endless. The final hint though is: Make sure you have clean and plentiful power. Make sure your data is clean. After that failures are caused by broken pixels.


    2019 - Going to visit my Daughter in New Zealand (again). I will be dark for the 2nd year in a row. Sigh..

  3. #23
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    Default Re: Injected pixels instantly light up bright white when plugged in with pc power sup

    Make sure you have clean and plentiful power. Make sure your data is clean. After that failures are caused by broken pixels.
    Hi, good advice.

  4. #24
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    Default Re: Injected pixels instantly light up bright white when plugged in with pc power sup

    Quote Originally Posted by MartinMueller2003 View Post
    Thanks. The Permutations are almost endless. The final hint though is: Make sure you have clean and plentiful power. Make sure your data is clean. After that failures are caused by broken pixels.

    Thank you for the info. The pc power supply wasn't a first choice, but one out of necessity when I realized it was a gong show trying to run injection from the other meanwell supplies. But, from what I've read, these pc supplies are great for many things specifically because they supposedly have a very clean and stable output seeing as they normally power mission critical pc functions and data. The data probe to find a dead pixel is a great Idea, but how would I go about testing if my data is clean or corrupted? Is there some kind of reader or trick to use?

  5. #25
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    Default Re: Injected pixels instantly light up bright white when plugged in with pc power sup

    Sequence errors is one sign of data issues whether it is visual on the pixels or
    error counts visible in the controller's config .

    I have read some here post about noise- even ringing and reflections on the data line , but you need to have extremely
    large ears to hear it and one heck of a humongous mirror to see the reflections .

    Seriously though , without a logic probe or a scope you are limited in doing any technical data quality testing .

  6. #26
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    Default Re: Injected pixels instantly light up bright white when plugged in with pc power sup

    process of elimination. Assuming you have clean power:

    If some lights work fine and the rest flicker: You have a bad pixel. Replace the last good and first bad pixels (I always do both. 50/50 chance if you replace only one. Murphy makes sure those odds are 100% wrong choice).

    If the very first pixel in the string is flickering (and the rest are as well), Plug a string directly into the controller. If it does not flicker then you may have a run too long issue or the first pixel in your string has gone bad.

    Take your pixels and plug them in as close as possible to each other (or into a known working controller). If the lights work then you need to place a null pixel or driver in the longer run. If they still flicker then you have a bad first pixel.


    2019 - Going to visit my Daughter in New Zealand (again). I will be dark for the 2nd year in a row. Sigh..

  7. #27
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    Default Re: Injected pixels instantly light up bright white when plugged in with pc power sup

    Quick update, still having the issues with the flickering, but the great news....Think I've finally figured out the very last always on white tree issue. Throughout this thread, i've gone froma few, to 4 to 6 all the way back down to 1 mini tree with issues, slowly but surely being resolved for different reasons. In terms of the last all white tree remaining that I swapped to last spot....I looked at both ends studying it closely, the pixels were the right direction, connections were good etc...Then, around the middle of the string something caught my eye, the arrow that's supposed to be facing the data exit point of the flow looked to be facing the wrong direction! Looked at both ends and a chunk of pixels at beginning and end, both correct directions, and I confirmed that none of the pixel wires were twisted or anything but flat between pixels to explain a reversed pixel. Looks like that particular run I got some really bad luck, and somehow a section of 7 pixels near the middle of the string were in backwards! yeah...That would do it. So I cut it out and reversed it and re-soldered it and will test it shortly and confirm success here Flickering still being a bugger though

  8. #28
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    Default Re: Injected pixels instantly light up bright white when plugged in with pc power sup

    Quote Originally Posted by XmasinVancouver View Post
    Quick update, still having the issues with the flickering, but the great news....Think I've finally figured out the very last always on white tree issue. Throughout this thread, i've gone froma few, to 4 to 6 all the way back down to 1 mini tree with issues, slowly but surely being resolved for different reasons. In terms of the last all white tree remaining that I swapped to last spot....I looked at both ends studying it closely, the pixels were the right direction, connections were good etc...Then, around the middle of the string something caught my eye, the arrow that's supposed to be facing the data exit point of the flow looked to be facing the wrong direction! Looked at both ends and a chunk of pixels at beginning and end, both correct directions, and I confirmed that none of the pixel wires were twisted or anything but flat between pixels to explain a reversed pixel. Looks like that particular run I got some really bad luck, and somehow a section of 7 pixels near the middle of the string were in backwards! yeah...That would do it. So I cut it out and reversed it and re-soldered it and will test it shortly and confirm success here Flickering still being a bugger though
    Wow, so those pixels came that way from the source?! Not good. Flickering issue: if your ground and data connections are solid and you are not trying to go a long distance form the controller to the first pixel, you may have electrical interference issues. These can be overcome by using twisted pair wires for data. The easiest way the do this is use Cat 5 cable which has 4 sets of twisted pairs. One of the pair is connected as data and the other ground. The twisting causes induced signals to be canceled out.
    Ed
    Happily retired

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