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Diagnosing pixel string short

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What is the fastest way to determine which pixel(s) have a short.  There is continuity between the 12v and ground wire on a 50 RGB pixel string.  I am hoping this is a problem with a single pixel, but not sure how to go about this without cutting each pixel from the string.  This is a new string and I am getting credit from the vendor, but I would like to determine if there is a way to find where the short is.   I originally tested to make sure I had continuity from ground to ground and 12v to 12v, but did not check 12v to ground until I blew 2 fuses on my pixel controller.  I would appreciate any ideas.

Thanks

Rick

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Start off with a very careful visual inspection.  See if you see anything that looks like damage to wires or pixels.  If you don't see anything, then you likely get to cut in half and see which half it's in, keep repeating until you find it.  All that is assuming that you DON't have a Time Domain Reflectometer.  If you have one of those, it will give you the distance to the fault to within a few inches.

 

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Wish I had a TDR!

 

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30 minutes ago, Vince4xmas said:

Wish I had a TDR!

They do come in handy!  I don't own one, but have access to them.

 

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Another Idea

If you have a current regulated supply, set it to a low, 'safe' value for your strings conductors/traces  and use an IR camera or probe to read the temps along the string. Where it goes cold, is near the problem

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20 minutes ago, TheDucks said:

Another Idea

If you have a current regulated supply, set it to a low, 'safe' value for your strings conductors/traces  and use an IR camera or probe to read the temps along the string. Where it goes cold, is near the problem

Good suggestion.  I should have thought about that one - I have access to a fairly decent Thermal Imaging Camera...

 

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Found the bad pixel.  Took Jim's advice and looked at the wiring 1st.  Noticed the wiring for one of the pixels was twisted.  I cut on one side of this pixel and checked the continuity.  The section without this pixel did not have continuity and the section with this pixel had continuity.  I then cut the pixel out of the 2nd section and checked continuity again on this section.  No continuity.  I believe I found the bad pixel, but have not had time to power them up.  Thanks for everyone's help.

Rick

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Glad you found it.  Sometimes people forget the obvious.  Just taking a detailed look can often find a problem - with all kinds of stuff...

 

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Yep. I struggled last year with an issue and finally found 2 wires switched on a pixel node from the factory!

 

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