Is my Neopixel Strand fried?

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thejennabird
 
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Is my Neopixel Strand fried?

Post by thejennabird »

I have an Adafruit Neopixel LED Dots Strand—4" pitch (https://www.adafruit.com/product/3631) connected to a pre-programmed WS2812B RGB LED controller I purchased from Amazon (product B07FSFXJ1S). The power source is currently a 5V 2.1A USB charger. I initially hooked everything up to a wall outlet charger I thought was 5V, but wasn't at home with a multimeter to check. I suspect I'm now paying for that foolish assumption.

When everything is connected to the 5V USB charger, the blue and green lights in the first Neopixel glow faintly. No other lights, no response to the controller.

The wires appear to be correctly oriented and connected:
  • the 5V wire on the controller goes to the red wire on the 'IN' side of the first Neopixel
  • the 'D' data wire on the controller goes to the middle wire on the 'IN' side of the Neopixel
  • the 'G' ground wire on the controller goes to the final wire on the 'IN' side of the Neopixel
Multimeter confirms the LED strand is getting ~4.65 V from the controller. Testing for continuity at the first Neopixel, the measured value was consistently around 100 ohms, no beep = resistance fail.

Did I accidentally fry the strand with the first charger? Is there any way to salvage the LEDs at this point, or did I just spend $30 learning to never again assume the voltage of a power source? Thanks in advance for any help!
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Faint blue and green glow in first Neopixel of strand when connected to pre-programmed controller, 5V USB power.
Faint blue and green glow in first Neopixel of strand when connected to pre-programmed controller, 5V USB power.
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dastels
 
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Re: Is my Neopixel Strand fried?

Post by dastels »

First, verify that the connections are correct.

Dave

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thejennabird
 
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Re: Is my Neopixel Strand fried?

Post by thejennabird »

Thanks, the connections are exactly as I listed (see photo). Note that the green 'D' line comes from the bottom of the controller and goes to the middle port on the JST connector. This then connects to the middle wire on the Neopixel strand.

Edit: 4.65 was the voltage as measured on the far (output) end of the strand.
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dastels
 
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Re: Is my Neopixel Strand fried?

Post by dastels »

That looks good. You should insulate where you have then soldered to the connector wiring.

Is it possible to test the strand with an MCU board like a Feather or even an Arduino UNO? The controller is an unknown.

What voltage was the wall charger that you first used?

Dave

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thejennabird
 
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Re: Is my Neopixel Strand fried?

Post by thejennabird »

The markings are worn off, but I got 7.5V from the wall outlet charger when I finally measured. The whole LED setup was plugged in for about a minute while I checked the connections and tried to get the strand to turn on. Would that be enough time to fry the entire strand? Would the voltage-mismatch prevent the lights from turning on at all? I suspect yes to the first question, not sure about the second.

For the heck of it, I just tried removing the first Neopixel in the strand to see if the second one worked. No luck, LEDs remain dark. The weatherproof casings make it difficult to check the remaining Neopixels to see if they've all gone bad.

The controller does seem to be a wild card in all this. I'll see about getting a Feather M0 Express and another LED strand while I'm at it.

I have zero Python experience and was hoping to avoid programming if possible. Unfortunately there doesn't seem to be a "plug-and-play" widely spaced (10 LEDs/m) 5050 LED strand that isn't already diffused by globs of epoxy. Like pre-programmed fairy lights, but bigger and without the blobs.

I guess I'll be learning CircuitPython. Thanks again for your replies!

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dastels
 
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Re: Is my Neopixel Strand fried?

Post by dastels »

If the over voltage fried the strand it would likely be pretty instant. 7.5 isn't a lot more, but those things are only rated to 5v, so anything more than a couple tenths of a volt above that is likely a problem. If the LEDs or their controller chips (in each Pixel) got fried then it would be permanent.

Dave

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thejennabird
 
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Re: Is my Neopixel Strand fried?

Post by thejennabird »

Roger that, thanks for the info. I learned the hard way this time but won't make the same mistake again!

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Disciple
 
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Re: Is my Neopixel Strand fried?

Post by Disciple »

The pixels may not be dead. ("I'm not dead yet!")
I see the controller label indicates that 5-12V is its input range, so I'd figure that a regulator is in there somewhere. Whatever the problem is, seems like 7.5V wouldn't be my prime suspect. Once you get your CircuitPython system completed, the original strand may respond to it. Lots of people have taken a liking to CP, and I believe you will, too. Best of success.

Hallelujah!
Disciple

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dastels
 
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Re: Is my Neopixel Strand fried?

Post by dastels »

Yes. trying it with the Feather is the first step. Power it with 3.3v from the Feather. That should work fine for 20 pixels and will avoid needing a level shifter.

As for the controller having a 5v regulated output, the product listing on Amazon says:
must use DC5V power supply .Input voltage=output voltage.
With that in mind, the controller might be fried as well.

Dave

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Disciple
 
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Re: Is my Neopixel Strand fried?

Post by Disciple »

dastels wrote:As for the controller having a 5v regulated output, the product listing on Amazon says:
must use DC5V power supply .Input voltage=output voltage.
With that in mind, the controller might be fried as well.
Ouch. Listing versus labeling. Still, if it were me, I wouldn't recycle the strand just yet. As you see fit.

Hallelujah!
Disciple

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dastels
 
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Re: Is my Neopixel Strand fried?

Post by dastels »

Yes, definitely try it with the Feather. You never know.

Dave

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