ws2812b external power - lights are weird and doesnt work- works from USB

I have a 1M 144 WS2812b strip.
I can upload sketches and run them just fine using ON BOARD USB power.

But if I just plug in an external power supply, all the lights turn on a light shade of blue.
Plenty bright - not a very low, hazy, flickering amount.
YES, I disconnect internal power to the strip when trying this.

I have a PS I bought off ebay 5v, 8a
and a old Linksys Router wall brick, 5v, 2a

The 8a, when plugged in blinks 3-5 LEDs quickly. Then nothing.
The 2a turns them all on.

Sorry, I’m looking for my Voltmeter.

There’s a pigtail on the strip for external power - which is where these plug in. And on the 3 wires from the CORRECT end of the strip, only Signal and Ground go to my breadboard. So, the grounds are ties together (as both are soldered together at the strip)

Any ideas?
thx

What kind of Arduino? Post your schematic, we need to see what resistors and capacitors you have connected.

Thanks for asking, but the strip shouldn't just light up all bluish-white just because I applied power... with no MCU attached to it.

I have a 6.3v 270uF cap across power lines coming into the strip on the external power feed.
And the resistor on the data pin. I've read all the precautionary and setup info on this.

Jaymer:
the strip shouldn't just light up all blue just because I applied power... with no MCU attached to it.

Some do. Some don't.

What about my other question?

oh, sorry. i have a mega.
edited: am using a NodeMCU now - forget the Mega.

Ok, so it's a 5V Arduino. Many people have problems controlling these strips with 3.3V Arduino like NodeMCU, MKR1000 etc. A logic level convertor of some kind is often needed with 3.3V Arduino.

Can you post some pics? Close-up and well-lit & focussed. Also your test code (Use code tags please).

How long is the data line from the Mega to the strip?

Are you ok with cutting one or a few LEDs off the far end of the strip? You can use these for testing on the breadboard using usb power.

not going to cut off leds.

I also have a NodeMCU v1.
Using this, the strip works fine with a sketch - in fact, a complex FFT music blinking reactive thingy.

Works fine on usb on-board power.
Issue is on external power.

And, as stated, the issue is BOTH external power supplies - doing weird things with the LEDs, even when its not plugged into anything, even data.

With USB connected, I have power & ground going to LEDs.
All works fine.
Green LED turns on after the program has connected to my network.
The capacitor is still in the circuit on the external power input, even though its not plugged in.

If I try external power (disconnect USB), the program still starts and connects to network and turns on green LED.
But no signal control is seen on the LED strip.
Using the 2a PS still turns on ALL Leds to faint bluish-white (R G & B are all on a tiny amount).

I has a similar issue with my WS2812B strip this week it would flash a neon blue color or neon green and it was because i had a short on my ESP8266, worked fine for a steady color but no fast speed pulsing, though the same code worked fine on an Arduino Nano or Uno and ESP32. I suggest you check your earth and data is clean and that you are at least have a 200 Ohms resistor on the data line too else try another pin i guess.

Back in post #2 you said

I've read all the precautionary and setup info on this

which gave the impression you were a meticulous and careful person. But now you posted pictures of an led connected directly to an Arduino pin with no series resistor.

I admit I don't have any idea why your circuit is not working, but I have to say I now wonder if you damaged something through carelessness.

KawasakiZx10r:
I has a similar issue with my WS2812B strip this week it would flash a neon blue color or neon green and it was because i had a short on my ESP8266, worked fine for a steady color but no fast speed pulsing, though the same code worked fine on an Arduino Nano or Uno and ESP32. I suggest you check your earth and data is clean and that you are at least have a 200 Ohms resistor on the data line too else try another pin i guess.

hey, thanks for the reply.
you can see from the new pics posted below, that I have (2) 1k resistors in parallel giving me 500 Ohms on the data line. (those were the only ones I had)

remember the [data] pin works fine and lights the strip perfectly using USB power. So data isn’t the issue, nor is my Greed LED signal.

My external power is always coming from the supplied pigtail - maybe I’ll try powering from the other end.

applied power from the other end and get exactly the same results.
doesn't look like a ground problem.

Jaymer:
applied power from the other end and get exactly the same results.

Hang on, it is not a matter of applying power from one end or the other - you should apply power to both ends and preferably every 50 (3 Amps) or so LEDs.

The series resistor and capacitor should be at the connection to the strip itself if there is any significant length of wire between power supply or Arduino and the strip, though this is not likely your present problem.

I would like to see the voltage measurements taken at the power connection to the strip in each of the cases you describe. I don't think I have seen them specified so far.

"Hang on, it is not a matter of applying power from one end or the other - you should apply power to both ends and preferably every 50 (3 Amps) or so LEDs."

Yes, sure, under real operation and to prevent brightness decay.

But now, I'm just trying to figure out why when I use external power (ONLY + and -), I get all LEDs turning (blueish-faint-white).
Yet, normal operation (fastLED set to 50% brightness max) when MCU is driving them.

But now, I'm just trying to figure out why when I use external power (ONLY + and -), I get all LEDs turning (blueish-faint-white).

Like you were told [ scouse accent] "they do that don't they". [/ scouse accent]

It means nothing and there is nothing you can do about it.

Get over it.

  1. propa wazzock in a fettle. si doon (geordie accent)
  2. well, the lights always stay on, even when i'm running my sketch, so its not like I can 'get over it'

Jaymer:
2) well, the lights always stay on, even when i'm running my sketch, so its not like I can 'get over it'

Why eye but thars nit what you sarn in yem’s last post

But now, I'm just trying to figure out why when I use external power (ONLY + and -), I get all LEDs turning (blueish-faint-white).
Yet, normal operation (fastLED set to 50% brightness max) when MCU is driving them.

Is that a 3V3 processor you have there? You need a driver to boost the signal to 5V if it is.