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Monthly Science: Final WS2812 Failures

My “exhibit” at the MHV LUG Mad Science Fair consisted of glowy and blinky LED goodness, with an array of vacuum tubes, bulbs, and the WS2812 and SK6812 test fixtures:

MHVLUG Science Fair - Chastain - highres_463020980

MHVLUG Science Fair – Chastain – highres_463020980

They look much better without a flash, honest. The cut-up cardboard box threw much needed shade; the auditorium has big incandescent can lights directly overhead.

Anyhow, what with one thing and another, the two LED test fixtures spent another few dark and cool days in the Basement Laboratory. When I finally plugged them in, the SK6812 RGBW LED array light up just fine, but three more WS2812 RGB LEDs went toes-up:

WS2812 LED test fixture - more failures

WS2812 LED test fixture – more failures

That brought the total to about 8 (one looks like it’s working)  out of 28: call it a 28% failure rate. While WS2812 LEDs don’t offer much in the way of reliability, running them continuously seems to minimize the carnage.

So I wired around the new deaders and took that picture.

Flushed with success and anxious to get this over with, I sealed the tester in a plastic bag and tossed it in the freezer for a few hours …

Which promptly killed most of the remaining WS2812 chips, to the extent even a protracted session on the Squidwrench Operating Table couldn’t fix it. When I though I had all the deaders bypassed, an LED early in the string would wig out and flip the panel back to pinball panic mode.

It’s not a 100% failure rate, but close enough: they’re dead to me.

As the remaining WS2812 LEDs on the various vacuum tubes and bulbs go bad, I’m replacing them with SK6812 RGBW LEDs.

For whatever it’s worth, freezing the SK6812 tester had no effect: all 25 LEDs lit up perfectly and run fine. Maybe some of those chips will die in a few days, but, to date, they’ve been utterly reliable.

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  1. #1 by scruss2 on 2017-08-01 - 17:26

    So I’m wondering: while you’ve learnt (and taught lots of others) of all of the possible failure modes of these cheap LEDs, wouldn’t it have been cheaper overall to buy the expensive ones in the first place …?

    • #2 by Ed on 2017-08-02 - 13:50

      All that fun: priceless! [evil grin]

      I always wonder if upping my spend would deliver better parts or a better return policy. Given the aggravation of rip-and-replace repairs with those vacuum tubes, getting a sack of replacement LEDs (or a refund) wouldn’t make me feel much better, particularly with onesie-twosies failures over the course of a year.

      The SK6812 LEDs, another bottom-dollar eBay purchase, seem to be holding up fine, so it’s time to ramp up production again …

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