NeoPixel 12 Discs

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junctioninc
 
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NeoPixel 12 Discs

Post by junctioninc »

Hello,

I have a large number of these discs (200), arranged in strings up to around 15 discs. I am getting an alarming failure rate (10%+) and issues with them. They are being driven from an Enttec Pixie driver (4off). Professional DMX to WS2812B signal converter with a built in PSU (110W @ 5v). To eliminate the drivers as being a problem we have swapped the drivers around to a working circuit and the problem persists, so I think it is safe to assuem the fault is with the discs or wiring.

Wiring is a power bus using 2.5mm2 cable with a 7x0.2 data wire. Bus length is <8m no data length is >4m. Usually 0.75m between discs.

Out of 8 strings currently installed, 2 are functioning without error. The others have all had pixel failures and 2 consistently fail. Pixels stick on and don't respond to data input. Resetting them fixes the issue for a short time and then the error returns.

Sometimes tapping or pressing the faulting pixel chip fixes the issue, suggested the issue is with the bond wire to the IC.

Some units supplied have not been reflowed, dry solder paste, and others badly.

Ideally someone from Adafruit Tech Support would get in touch.

But beyond this any real world experience with the installations of large numbers of these discs would be appreciated.

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adafruit2
 
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Re: NeoPixel 12 Discs

Post by adafruit2 »

hiya, thanks for the reply, if you see dry solder joints thats not good. if its the *first* pixel in a ring that's dying, its usually associated with having input voltage spikes on the data lines. this isn't nearly as common since we added a resistor but still can happen with data wires longer than a meter or so. if the pixels are breaking in the *middle* of the ring then that sounds like an actual failure.
can you post any pix showing the failures? It will help us debug them.
we can send you new rings, email [email protected] with a link to this thread and the # of rings

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junctioninc
 
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Re: NeoPixel 12 Discs

Post by junctioninc »

Hello,

It is not been the first pixel failing at any point. Always some way down the line. 3-10 discs in so a fair number of pixels.

I will send you some photos showing the non- reflowed units, but they just look like non reflowed pcbs. The components are attached because the paste has dried out.

The other failed units, will work after a power reset and then fail again. Often in a similar area. I'm drving to have a look at this this evening so will know more.

The issue with pressing on the chip to make it work feels like an issue with the parts?

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davidl13
 
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Re: NeoPixel 12 Discs

Post by davidl13 »

The issue with pressing on the chip to make it work feels like an issue with the parts?
Pressing on a chip to make it work implies a marginal/bad connection between the pixel package and the ring PCB, not necessarily an issue with the pixel itself. Many have resolved this by some touch-up soldering at the pads.

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