Author Topic: WS2811 pixel flicker only on white  (Read 478 times)

Offline rickswa

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WS2811 pixel flicker only on white
« on: July 28, 2018, 02:51:38 PM »
I just finished putting together my megatree for this year but have a problem I cant get rid of.  The tree is 36 strands of 60 pixels each.  The data output drives 6 strands each and every other strand is injected with power with the first two (data feed end) being physically isolated on the power side from the remaining 4.  There are no PSU's that end up being connected on the v+ end since each is isolated with the data feed that way.  I checked each PSU and they are both putting out 12v at the source.  I run a 5' extension that I cut one end off of to attach to the distro board and then connect to the strings.  At the end of the 2 string run, the voltage is 9.75.  One power supply is drawing 18v on full white and the other 14, a third is only used for 2 of the data segments so it's a very low load on that one.  Everything is fine until I go to full white.  I have the F16 set at 30% brightness but I keep getting random flicker on various full strings and/or random individual pixels.  I had thought maybe I had a grounding issue, but all 3 supplies are tied in together on the v- side and I also tried to cut the v+ and v- on a couple of the strings to isolate each two string run but that really didn't do anything.  It seems its worse at times than others and I just cant get it figured out.  I'm wondering if the location (utility room) causes interference but It seems to do this regardless if the a/c kicks on or not.  There is also a wire to a light right above it, but I turned the light off and same results.  Is it possible that the 5' run with the extension and then 2 60' strings is too long for that gauge wire?  Any ideas on what else I could try to get this to stop flickering?  Thanks for any help.
Here's a short video of the issue
http://www.youtube.com/watch?v=tXxzed-Wx1Y&feature=youtu.be
« Last Edit: July 28, 2018, 02:59:13 PM by rickswa »

Offline Ebuechner

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Re: WS2811 pixel flicker only on white
« Reply #1 on: July 28, 2018, 04:16:43 PM »
I looked at your video and I had a similar problem with some of the nodes that I got from Ray Wu.
Just like you everything worked fine until I put it on full White and then I would have random flickering that I was able to trace down to just a couple bad nodes that would corrupt the data and send it on when it was on full White.
I replaced the first node that was acting up in the string causing the flickering which cured the problem going down the line. I think I was running into about one out of a hundred that would cause the problem.
Not saying that's what your problem is for sure but that was my experience.


Offline rickswa

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Re: WS2811 pixel flicker only on white
« Reply #2 on: July 28, 2018, 09:26:23 PM »
Thank you for the reply.  After dreading the bad pixel issue you had, I looked at it some more.  It seemed to flicker by strip or set of strips rather than one pixel.  After messing around some more, I think I may have a grounding/interference issue.  I used 2 V+ and - outputs on 2 of the PSU's and one output on the other.  To connect the V- among the supplies, I just used one wire and connected it to one of the active outputs.  To test the issue, I disconnected those V- wires between the PSU's and essentially the entire tree quit working.  I then got a dristro block and connected all the V- outputs to that.  The flickering substantially decreased and just when I thought I had it, it would act up again.  I did notice that the romex for the light in the ceiling was only 2-3" from the top of the tree and the top clips and topper I use are metal so I tried as best I could to move it a little further from that wire.  It wasn't much of a move, but it seemed to decrease the issue even more and the only flickering is among the two strips that are closest to the romex above.  I'm going to try it again tomorrow to see if this really helped or if I'm back to square one.  Do you think I should cut the V+ or V+ AND V- between the set of 4 strips so that each set of two strips is isolated as far as power is concerned?  Where there are 4 strips that are powered from each end of the set of 4, the PSU is the same for all 4 strips.  Thanks again for your help and advice.

Offline aknflyer

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Re: WS2811 pixel flicker only on white
« Reply #3 on: July 28, 2018, 11:46:54 PM »
I had the same issue with random flickering on my megatree. I put it to full white and found 2 flickering pixels, replaced them. Then ran each color in test mode. Found 2 more bad pixels. Replaced those. Problems all solved, ran great all winter.

Offline Emuney18

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Re: WS2811 pixel flicker only on white
« Reply #4 on: July 29, 2018, 05:37:27 AM »
Just a clarification. Are you keeping the ground wire constant and unbroken coming from the controller along with data?  This is the correct way and I couldn't understand from what you wrote if that was true.


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Offline rickswa

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Re: WS2811 pixel flicker only on white
« Reply #5 on: July 29, 2018, 09:27:52 AM »
Ohhh.  After reading that question, I think my issue may be somewhat self induced.  So for each "chunk" of 6 strings on the tree, I ran the data and voltage from the expansion card to string one (plugged in at the bottom of the tree).  Then at the top, string was is connected to string two.  Now here is where I may have done a bad move.  Thinking it would be easier to use 2 core extensions for injection, I cut both the v+ and v- on string 3 and soldered a 2 core pigtail on it.  So on string 3 there is both the original 3 core (with data passing thru it only) and the two core for injection.  This is then constant and unbroken all the way thru string 6 where a 3 core extension (using only v+ and v-) is connected at the end.  Then this repeats for the rest of the groups of 6 lights around the tree.  Was cutting both the v+ AND v- not such a great idea?  In some of the sections of 6, the same PSU is powering all strings, but in others, string one and two use a different PSU than 4-6.  I know it's probably not much more clear the way I described it, but I've attached a crude drawing of what I think is a big error now..... I tried to show both the single psu section setup and the ones that use two.  On the ones that use two, psu 2 is connected to an 8 way distro board and powers strings 4-6.  on the single psu setup, psu 1 powers the expansion card that goes to string 1 and thru 6 but also is connected to a 4 way distro board that powers 4-6.
« Last Edit: July 29, 2018, 09:40:43 AM by rickswa »

Offline Ebuechner

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Re: WS2811 pixel flicker only on white
« Reply #6 on: July 29, 2018, 11:23:48 AM »
Trying to keep this explanation simple.
The only wire you need to sever is the positive when the power is coming from a secondary power supply.
If everything is coming from a single power supply you can tie the power to power and negative to negative together at multiple points without an issue.
My mega tree has three strips per output on my controller and I use a 16 gauge Three core wire to feed all 3 strips and the power feeds into the base of each of the three strips so I don't have the need for additional wires for power injection.

Offline Emuney18

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Re: WS2811 pixel flicker only on white
« Reply #7 on: July 29, 2018, 06:01:04 PM »
Rickswa try wiring the negative back together even if that's just twisting them together temporarily on one of your 6 strand sets and see if it fixes it.    Basically add a blue or red line, whichever is V-, with your single yellow line in the drawing.   I hope that's your problem and then do it permanently for all strands.


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Offline rickswa

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Re: WS2811 pixel flicker only on white
« Reply #8 on: July 29, 2018, 06:05:51 PM »
Thanks again for taking the time to help me out with this.  After much frustration at myself, I went back to the strings where I injected both the v+ and v- and cut and resoldered the v- back to the 3 core "string to string" pigtail with the data.  This allows only v+ to be injected into that point and keeps the ground and data consistent thru the 6 string runs.  SO FAR this seems to have fixed my issue.  I've tried it a few times throughout the day to make sure it wasn't going to act up again, but so far it seems this might have fixed the flickering issue.  Thanks again for helping me out and hopefully this was the fix I needed.

Offline rickswa

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Re: WS2811 pixel flicker only on white
« Reply #9 on: July 29, 2018, 06:06:49 PM »
Thanks Emuney.  It seems we were posting at the exact time lol.  Thanks again for being such a help.  I REALLY REALLY appreciate it.

Offline Emuney18

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Re: WS2811 pixel flicker only on white
« Reply #10 on: July 31, 2018, 06:24:27 PM »
From the injection power supply you still will want to have V- from that power supply connected to your strings somewhere. If they are all connected through some type of common ground it will be fine, such as a ground bar or extra wire that connects the power supplies V- together. It's usually easier to just connect the V- at the site of injection in line with the existing V- of the string.

 

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