Sk6812 strips initially Unstable

I’ve had a 2 meter strip set up and working beautifully for maybe a year.

Now, when they first startup they flash random colors but after a minute or so will eventually stabilize with only the occasional relapse. The worst of the flashing tends to be on the side furthest from the controller (Wemos D1 mini).

A single 5v 20A power supply is used for the strips and the Wemos d1 mini, and the d4 pin if the mini passes through this level shifter: and then a 470 Ohm resistor.

I have changed the 1000 uf capacitors, and added a third power injection point at the far side of the strips, checked various contacts, fiddled with settings, even switched the pins on the level shifter, and I still can’t get the dang thing to work like it used to.

LED # 25 seems to constantly be the point where the correct color stops (it itself is off), and down the line goes wild. Led #25 was for some time the location of a rather sharp turn in the strip. When the rest of the strip stabilizes, this LED turns on as expected.

Additionally, the webui has occasionally been unresponsive recently.

What do you guys think could be going on?

My next port of call considering you’ve already tried a few things would be to try another strip. Issues can sometimes arise when a pixel or pixel IC goes faulty in some way. I’ve had this myself on one occasion. It can sometimes happen over time when led’s are driven hard at full brightness. Maybe start at pixel 25-26 as a faulty pixel could be generating noise to the remainder of the strip.

Other than that have you placed any RF equipment close to the controller in recent times which could be inducing noise into your setup?

Thank you so much for your response.

I was worried this might be the case, I’m sorry it’s happened to you as well. I would love to learn more

No big RF changes recently, but the controller sits on top the 20A supply and there are quite a few A/V cables surrounding the strip. However, it was working before in this configurarion which fits well with your wear and tear description.

I spent a bit more for the 144 led/meter and it wouldn’t be financially responsible for me to replace them. Do you think It would be viable to sever the suspect pixel from the strip with some flush cutters/razor?

Also, why do you think they eventually stabilize? Heat? After maybe 1-2 minutes everything stops seizing and I regain control.

This situation has been boggling my mind for 2 days, I would love to understand it better.

Thanks again

These intermittent faults can be a pain to solve.
Heat could be an issue especially when displaying white and other static colours at full brightness. This could be creating a poor connection on a weak solder joint across a certain data line. Dry solder joints are often common on components that heat up over time. It’s something to explore although could be tricky to actually find.

Another suggestion before you start dismantling your strip. Perhaps try re-flashing your Wemos D1 mini or flash another one and see what happens. Worth a try and won’t cost anything.

Good luck and let us know how you get on

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My recommendation is along the lines of what you are already thinking.

Here’s the what:
Repair damaged strip around pixel 25 by removing any damaged sections of the strip and stealing replacements from the ends of the strip and insert around the damaged section but this time, instead of allowing the strip to bend between pixels 24/25, have wire going around the bend.
Here’s the how:
Cut the strip before the sharp bend between pixels, presumably between pixel 24 & 25.
Inspect both sides of the strip for damage a couple pixels away from the cut.
You will now remove and replace (perhaps cutting from the far or near end of the strip) any pixels that are surrounded by visual damage or signs of overheating (localized discoloration).

Now prep some heat shrink (and hot glue / epoxy / resin to coat the exposed strip for outdoors applications) and solder wires between all the cut pieces of the strip (around pixel 25 and around any removed pixels as needed). Don’t heat shrink it all together just yet.

Power up the strip and update the WLED pixel #, reducing by how many pixels were removed to repair the bend. Restart WLED after updating pixel #. Pay particular attention to temperature and color consistency around pixel 20 through maybe pixel 35. Maybe take a picture with your phone, and then do some magic with a PC program to capture “pixel” color values around each of those pixels (if it’s to subtle or if you’re even a little color blind).

Now you can objectively know whether all the pixels are getting full current and outputting properly if they are all about the same color value (I use Micro$oft Paint and click on pixels to see their value).

If everything is acceptable, heat shrink the connections and maybe add a wire fastener over the center of the heat shrink (away from the solder joints) so it does not move around.

The strips are bendable, but as you have seen, bending them weakens them permanently. Some weakening is fine, but if you want full power, any weakening is going to eventually generate a hot spot and failure point.

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Incredible responses guys, thank you so much for all your support.

The wire around the bend idea is great, now I know to go with that from the start whenever I set up another one. Also I love the idea of digitally checking for color consistency, very well put.

Interesting bit about the dry solder joints. After I open it up i might reflow some of the suspect pins just to see.

Also to satisfy some curiosity, reflashing and switching D1 minis was part of the troubleshooting I’ve done since. Even changed the power supplies. Same same. Looking more and more like an issue with the strip.

I’ve contacted the manufacturer on aliexpress (BTF-Lighting), they’re interested in seeing a video for product improvement .

I’ll probably get after the repair this weekend. I may just abandon the bend alltogether. Will get back to you with an update soon.

Thanks again. Very helpful :smiley:

I followed the above advice and excised 6 LEDs across the two 144 LED/m strips, all of which were off and marked a transition in color, and everything is now working again as expected.

Only three of these were located close to the bend.
The other three were located in seemingly random locations.

In an effort to preserve the longevity of the LEDs remaining I have limited the estimated current limit to 6000 mA.

Did you see any visible signs of damage around the removed pixels?