Need suggestion on fixing freezing pixels.

[roberth58]

I have started having problems with pixels freezing on random props. It is happening on K16, K32 and smart receivers, running FPP 8.4. The prop can freeze during a sequence with all the correct pixels lit, it can be a single or multiple pixels randomly on the prop in random colors. If I unplug the prop and plug it back in a few seconds later everything will start working again from 10 minutes to 3 days. I have changed cables from controller to prop, swapped all pixels on 2 props, rendered all sequences again and uploaded. So far nothing has helped. The weird thing is the show runs 5 hours a night and some nights it will run without a single glitch. Any suggestions on what to check?

thanks

Bob 

[jnealand]

If you can figure this one out let us all know.  You will be a certified hero to us.

[Poporacer]

Sounds a lot like moisture intrusion.

[roberth58]

Weirdly this is probably the driest December in NW Florida in a long time. Only been one rainy night and that was 2 weeks ago. If moisture is the problem would pulling the plug for a few seconds fix it?  

[darylc]

intermittently faulty pixels, super common

[LedMutt]

If moisture is a problem like Poporacer suggested, try using dielectric grease on the connectors, I have been using it for years now, it could be a little messy but it helps alot...

[roberth58]

thanks, I'll try the grease in the connectors. I have found one thing that was causing problems, heat shrink solder connectors. I have replaced some custom length extensions I made with those connectors, using standard 5/10/20 cables from wired watts. So far I have changed cables going to 6 props and freezing and glitching seem to have stopped. If this lasts I'll change all my custom extensions. Still having some weird problems unfortunately, like a 350 pixel wreath, first 103 working perfectly then dead until pixel 297 which is stuck on blue and everything after is dead.

[JonD]

like a 350 pixel wreath, first 103 working perfectly then dead until pixel 297 which is stuck on blue and everything after is dead.

Assuming these were working at one point, it sounds like a bad pixel.  Replace the first pixel that is not working (104?) and the working one before it (103?).

[roberth58]

I have done the replace last good one and next one hundreds of times. The result can be 1,10,20 all pixels working or any other combination. I had a 99 pixel candycane thats had 17 pixels die, that's 34 pixels replaced, when it started glitching again a week ago I yanked out the bullets and replaced them with EVO's, hoping they survive longer. Whats freaking me out about the wreath is how is 297 getting power when 104-296 are dead.  

[JonD]

Replacing the first broken and the one before it is typically the first place to start.  If you have programmed 99 pixels in xLights and/or your controller settings, and you attached a 297 pixel light string, of course only 99 pixels are going to work.  Assuming 297 were working at one point, and they all of a sudden stopped working, it is probably a bad pixel.  Yes, I question this myself sometimes, and I have to convince myself to follow the rules, and the 2 pixel repair fixes it almost every time.

If this issue was at my house, I would use the below tester, set it for 297 pixels, and plug the light string into the tester to see if the lights all work.  If they don't work on the tester, it is most likely a string issue.
https://www.holidaycoro.com/DMX-to-SPI-Smart-Pixel-Decoder-Controller-p/614.htm

If the strings play correctly on the light tester, I use the F-test to make sure I am getting signal for 297 pixels.
https://pixelcontroller.com/store/diy-controllers/85-F-Test.html

If you don't have a tester, you might want to consider getting one.  Doesn't need to be one of the above.  Just something reliable that you know it works every time and that you can carry it outside for testing.

Whats freaking me out about the wreath is how is 297 getting power when 104-296 are dead.   

This will happen when there is a bad pixel sometimes.  Most light strings need to be power injected at around 170-200 pixels.  Are you power injecting these?  Some lights will work under powered, but at the cost of a greatly reduced lifespan.

[roberth58]

Jon, I have been talking about a 99 pixel CANDYCANE and a 350 pixel WREATH. There is nothing with 297 pixels. Yes I have a tester and also there is a tester builtin to the K16 and K32. My pixels are the low wattage resistor style and I have no problems running 300-350 at 30% with no power injection, I run 600 with power balancing, over that I add power injection. Most of my pixels that are causing problems were bought in 2020 and I think they are just flaky and I am slowly replacing them with EVO's. As an example, 2 days ago a spiral tree with 121 pixels had a problem. Pixel 68 started flickering and 69-121 would freeze randomly. I replaced pixel 67 and 68, using clickits instead of heatshrink solder connectors. Started working again. Last night the same tree had pixels 98-121 dead.

[k6ccc]

I have found one thing that was causing problems, heat shrink solder connectors.

Why does that not surprise me?  I have never used those and would not trust them.  Even when done with a proper soldering iron with a proper amount of heat, just laying the two wires next to each other and melting a blob of solder over them is NOT considered a good solder joint.  Then add the complexity by not even properly heating the wires, and you are asking for a crappy connection.  The wires need to be mechanically connected (twisted or wrapped together) and then the wire needs to be heated enough to melt solder - NOT melt solder with the iron and have it blob over only warm wires.

[JonD]

"I have been talking about a 99 pixel CANDYCANE and a 350 pixel WREATH"  I had just pulled numbers out of thin air, and was not referring to your candy cane.  The 2 pixel repair is cutting out the last working pixel and the first non-working pixel and replace them both.  The problem is going to be one of two.  It is easier to replace both than try one and then have to do it again if you guessed the wrong one. 

"Whats freaking me out about the wreath is how is 297 getting power when 104-296 are dead."  I have seen random pixels lit after the actual break on multiple occasions.  This happens and should not be freaking you out.

"I have no problems running 300-350 at 30% with no power injection" 300-350 lights is a lot of lights without power injecting.  Just because you have not noticed any visual problems, does not mean they do not exist.  What matters is if you have placed a multi-meter at the end of your string and verified the remaining power exceeds the manufacturer's recommendations.  If you are running them under powered, it is possible this will greatly reduce their lifespan adding to your problems.  If power is still meeting manufactures recommendations then that suggestion would not apply.

Wind is not your friend.  Make sure your pixels are not swaying in the wind as much as possible.  If you bend a solid wire enough times it is going to break.  Stranded wire will do the same over time.  I originally had to make a half dozen repairs to my deck matrices every season.  I noticed that the wind was really pushing them around and started zip tying them to the railing so they could not move.  I don't think I have repaired them since.  If your pixel wires are flopping in the wind, you are most likely going to have to repair them more often.

"I replaced pixel 67 and 68, using clickits instead of heatshrink solder connectors"  The 2 pixel repair would have resolved this as the bad splice would have been between the last working light and the first dead one.  "I think they are just flaky and I am slowly replacing them with EVO's."  The 2 pixel repair also fixes flaky lights.  I once had to do the 2 pixel repair 4 times on one strand, but the light string was working once I completed all of the repairs.  If you have to repair all the time, it certainly might make sense to replace the entire string, but the 2 pixel repair will resolve this until you decide to do so.

[roberth58]

"I replaced pixel 67 and 68, using clickits instead of heatshrink solder connectors"  The 2 pixel repair would have resolved this as the bad splice would have been between the last working light and the first dead one

I don't understand this. 68 was the first bad pixel and 67 was the last good one. I replaced then both, a splice before 67 and a splice after 68. I did not replace the 2 pixels individually.  Are you saying that 68, the flickering pixel was the last good one and I should have replaced 68 and 69.

[k6ccc]

When there is a bad pixel that is killing or distorting the data signal, there is a question on which one it is.  It can be the last properly lighting pixel, or it can be the first failed pixel.  Without some more involved testing, you can't tell which one it is.  Since pixels are fairly cheap and it takes time to swap them, most of us just replace both (my time is more valuable than the cost of replacing one extra pixel).