Archive for February 13th, 2017

Cheap WS2812 RGB LEDs: Continuing Failures

Three more knockoff Neopixels failed in the last few weeks, including one that can’t possibly suffer any thermal stress:

Halogen bulb brass cap - overview

Halogen bulb brass cap – overview

I wrapped the halogen bulb in a shop towel, laid the ersatz heatsink against an anvil (actually, it was a microwave transformer on the Squidwrench operating table), whacked a chisel into the epoxy joint, and met with complete success:

Failed WS2812 LED - ersatz heatsink

Failed WS2812 LED – ersatz heatsink

Having epoxied the PCB and braid in place, there was nothing for it but to drill the guts out of the brass cap:

Failed WS2812 LED - drilling

Failed WS2812 LED – drilling

Which produced a pile of debris in addition to the swarf:

Failed WS2812 LED - debris

Failed WS2812 LED – debris

The brass cap emerged unscathed, which was just about as good as I could possibly hope for.

The base LED in this 21HB5A also failed:

21HB5A on platter - orange green

21HB5A on platter – orange green

Soooo I had to unsolder the plate lead and Arduino connections to extract the bottom PCB; fortunately, that was just a press-fit into the base.

I should mount a 3.5 mm stereo jack on the platter and run the plate lead into a nice, albeit cheap, knurled metal plug, so I can dismount both the tube and the plate lead without any hassle. Right now, the tube can come out of the socket, but the plate lead passes through the platter.

For whatever it’s worth, all of the dead WS2812 LEDs pass the Josh Sharpie Test, so these failures don’t (seem to) involve poor encapsulation.

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