Strange Flickering issue

Issues
1

Hi everyone,

I’m hoping someone can help me troubleshoot a very persistent issue with my WLED installation.

Hardware

  • Controller: GLEDOPTO ESP32 WLED controller

  • WLED: Latest stable version

  • Signal amplifier: GLEDOPTO WLED Signal Amplifier (installed on Output 1)

  • Power supply: Mean Well UHP-350-5 (5V, 70A, 350W)

  • LEDs: SK6812 RGBW (5V)

Installation

Total LEDs: 1677

The controller has 2 independent outputs.

Output 1

  • Island 1

  • Island 2

  • Island 3

Approximately 800 LEDs total.

A GLEDOPTO signal amplifier is installed directly after the controller before Island 1.

Output 2

  • Island 4

  • Island 5

  • Island 6

  • Island 7

  • Island 8

Approximately 877 LEDs total.

Both outputs are powered directly from the PSU and share a common ground.

Main issue

Most animations work perfectly.

However, with some heavier animations (for example color chase animations where almost all LEDs are active), I get a subtle brightness flicker.

Originally I suspected the PSU, so I replaced my generic 5V 40A power supply with a Mean Well UHP-350-5 (5V, 70A).

Replacing the PSU made absolutely no difference.

Initially I thought both outputs flickered perfectly synchronized, but after observing more carefully this doesn’t always seem to be the case.

Sometimes:

  • only Output 1 flickers

  • only Output 2 flickers

  • sometimes both

The flicker is subtle. The controller does not reboot and the LEDs do not completely reset.

Additional issue

Yesterday I resoldered the data connection going into Island 2 because it had been showing corrupted colours.

After resoldering, everything appeared to work correctly.

However, around 4 AM I was woken up because the first few LEDs on Island 2 suddenly turned on bright white by themselves.

At that moment:

  • WLED was OFF

  • no animation was running

  • no commands had been sent

The only way to turn them off was to disconnect power from the PSU.

This morning I powered the installation back on.

The white LEDs were gone again and all normal animations worked correctly, except for the heavier animations that still produce the subtle flicker.

So this issue appears to be intermittent rather than permanent.

Things I’ve already tested

  • Replaced the power supply with a Mean Well UHP-350-5

  • Replaced the transport cable between Island 1 and Island 2

  • Verified continuity on all three conductors of the transport cable

  • Measured 4.88V directly on the input pads of Island 2

  • Bypassing Island 2 allows Island 3 to work correctly

  • Resoldering the data connection into Island 2 greatly improved the previous corruption issue

  • Signal amplifier installed before Island 1

One thing that confuses me is that the problems seem to appear and disappear without me touching the hardware. The installation can work perfectly for days or even weeks before the issue suddenly returns.

Questions

  1. Has anyone seen this type of subtle flicker on larger SK6812 installations?

  2. Since replacing the PSU made absolutely no difference, what would you investigate next?

  3. Has anyone experienced LEDs turning on by themselves while WLED is OFF?

  4. Could this be related to the GLEDOPTO controller, the signal amplifier, grounding, or signal integrity?

I’ve been troubleshooting this installation for several weeks, so at this point I’m trying to understand the root cause rather than continue replacing parts randomly.

Any ideas would be greatly appreciated.

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2

enable off refresh, disable automatic current limiter and test

3

tested it. Still flickers. I think it started to do this a couple of weeks ago, maybe after an update.

10

?? I am happy it improved preformance for you, but how does that explain why my setup is doing this? I dont understand the comment.

12

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13

Reply

I’d need a bit more detail to help narrow this down, but flickering issues usually come down to a few common culprits.

First, what’s your refresh rate set to, and does the flickering happen consistently or randomly. If it’s intermittent, that often points to a driver issue rather than hardware. Try rolling back your graphics drivers to a previous version—sometimes the latest update causes compatibility problems.

If it’s constant flickering, check your monitor cable connection. Loose or damaged cables are surprisingly common and will cause exactly this symptom. Try reseating it firmly on both ends. If you’re using HDMI or DisplayPort, test with a different cable if you have one available.

The refresh rate mismatch is worth investigating too. Go into your display settings and make sure your refresh rate matches what your monitor actually supports. Running mismatched rates creates exactly this kind of visual artifact.

One more thing: monitor your GPU temperatures while the flickering happens. If your graphics card is throttling due to heat, it can produce flickering as it adjusts performance. Use something like GPU-Z to check.

Also note whether it happens across all applications or just specific ones. If it’s only in games or specific software, that suggests a driver or application-specific issue rather than a hardware problem.

What monitor are you using, and what GPU. That context would help me give more targeted advice. Also, when did this start—was it after a system update or driver installation.