Determining which pixel is faulted

Discussion in 'RGB Lights - Intelligent Pixels and 3-Channel RGB' started by abundy, Aug 4, 2014.

  1. abundy

    abundy New Elf

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    Hi all..
    Just wanted peoples idea's on the following scenario


    2801 pixel string of 40 pixels.


    Pixels up to pixel 12 work. Pixels 13 is red then the rest don't work.


    I would like to remove the "bad" pixel from the string.


    One way would be to cut the bad pixel out. However which pixel is the bad one? DO i assume that it is pixel # 13, or could it be a bad output from pixel 12?


    Or


    Is it possible to mark the pixel as a null pixel? This would save a bunch of cuts/solders heat-shrink/silicone moments.
    The string is attached to a pixelite 16.


    Any thoughts would be appreciated.
     
  2. Superman

    Superman I Have C.L.A.P and its very infectious Global Moderator

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    it may be 13, it may also be 12 not passing on the data. cut and resolder both is the best practice
     
  3. davrus

    davrus Silent Elf

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    Setting it as a Null Pixel will not help, as the problem is almost certainly a physical electronic one, rather than just the data.
    If Pixel 12 is faulty, turning it off doesn't help to get the data out, and make the electrical connection better. You can see that if you do a test where you only try and turn on any of the pixels AFTER the faulty one.
    Have a good look at the potentially faulty pixel, you might be able to see something odd. I had one where the pixel wasn't pointing straight up, it was at an angle. Looking inside, I could see that the pixel was perpendicular to the board, as the board was at an angle, with the output side being high. This probably had caused a bad connection on the output wires.
     
  4. arw01

    arw01 Full Time Elf

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    Some people have had some luck with a test clip and a needle to hop over a pixel, and then some clear nail polish to seal the tiny hole left in the wire.


    Does not always work depending on what the "bad" pixel is putting on the line, but seemed to be pretty effective in finding the proper pixel with the issue.


    Alan
     
  5. fasteddy

    fasteddy I have C.L.A.P Global Moderator Generous Elf

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    As a rule I will generally change both pixels because more times than not its the output of the IC for the LED that is still working that has failed, but this is not all the time, sometimes the LED that is not working has the failed IC.
     
  6. damo1271

    damo1271 Full Time Elf Generous Elf

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    I agree with Fasteddy - replace both.
    I spent ages replacing pixels on my mega tree and most of the time it was the output from the last pixel that was lit, but then after being up there, cutting, soldering and heat- shrinking in the new pixel its such a pain to find out it was the input on the next pixel that was fried.
    I did use a jumper lead but found you had to cut the data wires to get a reliable output if the driver was a dud. Again by the time I cut the data lines before and after the the supposed dead pixel, connected jumper lead and tested, then soldered and heat-shrunk to repair the 'damage', it was quicker and easier to replace both!
     
  7. AAH

    AAH I love blinky lights :) Community Project Designer

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    It's always worth checking that you don't have a configuration screwup too. Any number of people get the channels and pixels wrong and think that they are putting out the right data but aren't. Your 40 pixels is reasonably close to the 40 channels that you appear to be controlling. You're controlling 36 channels (12 pixels) plus one (red) assuming you've got the numbers right.
     
  8. OP
    OP
    abundy

    abundy New Elf

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    Thanks for the input guys...


    I learnt a lesson the hard way from last year, and decided to test everything this year before putting anything up.
    I found this using the da_131 test utility so i know it aint a channel count issue, as the other 15 strings all checked out.
    I will cut pixel 12 and 13 out and stick them at the end of the string where they will have the least amount of impact.


    Cheers..
     

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