NeoPixel Ring Blues

EL Wire/Tape/Panels, LEDs, pixels and strips, LCDs and TFTs, etc products from Adafruit

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Barry914
 
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NeoPixel Ring Blues

Post by Barry914 »

I have been working with your support staff (Mike and Rick)* on getting my IDE to talk to my Gemmas, which bore (Ada)fruit today. That's the good news. The bad news is I have found more NeoPixel rings that don't work. It's possible that I killed them, maybe by reversing power and ground, but I don't think so. Is there some way I can check to see if I am the executioner or if they were DOA?

(edit)
OK, I'm looking at 3 of the non-functional rings and I see SMT devices (cap? resistor?) standing up on end, others cantilevered over it's pad on one end, and some other questionable connections. Looks like I'm not guilty, at least as far as these go. I have one other that looks OK but stopped working after a while. Want them back?

(Another edit)
Make that 5 bad rings. I was running the earring code (off a LiPo battery, no USB) and another ring became erratic. If I flick the ring with my finger, its behavior changes - some pixels will work, some will stay on, others will stop lighting up.

_______
* These guys deserve medals for not trying to convince me I should find a new hobby and stop bugging them. Or worse. Thanks again guys.

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adafruit_support_mike
 
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Re: NeoPixel Ring Blues

Post by adafruit_support_mike »

Please post photos of the rings that have the oddly positioned components. From your description, that sounds like something called 'tombstoning', which can happen during the reflow process. Our QA tests should catch any tombstoned parts though.

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Barry914
 
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Re: NeoPixel Ring Blues

Post by Barry914 »

This is a typical example of 3 of the 5 defective rings. The cantilevered components are much more difficult to photograph. The other 2 behave erratically when the board is flexed slightly or tapped with a fingernail. The 1 good one can be banged on the table with no change in behavior.

I should add that the original 2 rings I received from you (which you have already replaced) both failed while running strandtest, even though they had been running earring code for many hours. I suspect it was a heat related issue, also caused by poor solder joints. I did not see any tombstoned components on those rings however. So this makes 7 out of 8 bad rings. A bit disturbing.
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Barry914
 
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Re: NeoPixel Ring Blues

Post by Barry914 »

Just wanted to add I am about to place an order for some 12 pixel rings and a couple of more Gemmas. What, me worry? I assume these problems are not what I can normally expect from your products. Maybe it's time to get rid of the keg ... :lol:

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adafruit_support_bill
 
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Re: NeoPixel Ring Blues

Post by adafruit_support_bill »

That does look like a tombstoned component there. I will make sure manufacturing is aware of that. In the mean-time, please contact [email protected] with a link to this thread for replacement.

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Re: NeoPixel Ring Blues

Post by adafruit »

Thanks for the note, we do have all Rings pass test here - theres a bunch of capacitors on board, they're helpful for power management but not required so if one or two are tombstoned it *doesnt* affect functionality. Don't forget to add a 330 ohm resistor between DIN and DOUT pins and between your microcontroller & neopixel DIN pins *especially* if you have long wires!

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Barry914
 
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Re: NeoPixel Ring Blues

Post by Barry914 »

You mean in series with the data line to the NeoPixels? This is the first I have heard about this. Is this an impedance match thing or to reduce transients or something like that? At what wire length does that become necessary?

As for the tombstoned capacitors, I can see how losing a couple of bypass caps wouldn't seriously affect performance, but might that indicate issues with other reflowed parts? Based on the intermittent nature of the problems I've experienced I am guessing that is what's going on here.

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Barry914
 
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Re: NeoPixel Ring Blues

Post by Barry914 »

I was perusing the forums and I came upon someone who had problems with his NeoPixel rings. I tried what he tried; I removed pixel 0 and jumpered its input and output pads on the board. Now I have a gap-toothed but otherwise OK ring. So what did I do to kill it? If I had reversed Vcc and ground I suppose I would have fried them all. Connecting power and ground to data in and something else maybe?

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adafruit_support_bill
 
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Re: NeoPixel Ring Blues

Post by adafruit_support_bill »

There are a few known ways to kill them. Most involve a voltage spike either at power up, when connecting or something induced on the signal line. Based on feedback from users, we have been updating our guides with the recommended 'best practices' for handling and wiring. http://learn.adafruit.com/adafruit-neop ... -practices

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Barry914
 
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Re: NeoPixel Ring Blues

Post by Barry914 »

I probably violated every one of those best practices multiple times. Expensive lesson learned :(

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