Only first quarter of strip lightened and random blinking random colors


I can’t get my setup to work, only the first quarter of my led strip lightens up with random blinking and random colors, rest of strip stays off.

It’s a 128 led HD107S (21+20+46+20+24) driven by a lolin32 and a relay. Lolin is powered by micro usb and led strip uses 5V15A supply.
Board+relay+strip share the same ground. Clock and data are 20cm length.
When set to power I measure ~~5V at each corner. From board to first strip solder I measure ~~0 ohms on data and clock line. No short between +5/data/clock/gnd at each corner.
First led segment starts with the led paired with resistor.
Trying to solve this issue I’ve replaced everything with brand new, except relay and led strip #2,3,4 and 5.
I triple checked pins are correct: clock on 0, data on 2, relay on 12, relay power on 3V and gnd on gnd.
Here’s WLED setup:

Of course WLED is set to solid warm white.

Note if I change total led count to eg 130, then switch on/off through WLED, the whole led strip enlightens with random flicker.
Unplugging/replugging board from usb returns to previous state of first quarter enlightened.
Weirdly rebooting this way also reset WLED power switch to on.

I’m totally lost with this issue and don’t understand where’s the fail.
Help will be greatly appreciated !
Thank you !

PS: 2 aside questions:

  • is it mandatory to start the strip with the led paired with resistors ?
  • is there a way to check with a multimeter that data and clock are ok along the strip the same way you can check gnd and +5 continuity and voltage ?

Inject power (voltage +/- pair) from the far end of the strip and in the middle of the strip. That should fix the flickering.
How many segments do you have configured? If you only have one segment, make sure the segment 0 start / count values match the # of LEDs.

Hi and thank you huggy-d1
I just tested to inject 5V close to the middle and it doesn’t change.

My strip is cut in 5 pièces each for one side of my monitor and 2 for the bottom.
The way I understand WLED settings, each WLED segment is connected to different data/clock pin.
As my strips are driven by the same data/clock line on GPIO0/2 I set WLED to one segment only, as shown on picture.

I think I misused “flickering”, my leds are randomly blinking in random colors. Sorry I’m not native english I don’t know the correct word for this behaviour.
I edited the title and first message to be more clear.

Thank you.

How many LEDs are configured in segment 0?

set to 128 as shown in picture

In the posted picture (I looked multiple times thinking I missed it), the 128 number is the number in the entire strip.
There is a different configuration for segments. How many segments are configured and what are the start / count values for segment 0 - once you find the segment configuration screen.

AFAIK segments are set here under led outputs and you add segments with “+” button.
I configured 1 segment of 128 leds starting by 0.
Should I set 5 segments of 21/20/46/20/21 leds ?

Found ! It was a couple of dead leds.

So glad you figured it out. Those types of problems are tricky to find. Good job!