The Smell of Molten Projects in the Morning

Ed Nisley's Blog: Shop notes, electronics, firmware, machinery, 3D printing, laser cuttery, and curiosities. Contents: 100% human thinking, 0% AI slop.

The New Hotness

  • Vacuum Tube LEDs: Failed Tape, Failed USB Cable

    While packing the vacuum tube LEDs for the HV Open Mad Science Fair, I noticed the knockoff Arduino Nano inside one had come unstuck from the base. It seems the double-stick foam tape I’d used had lost its sticky:

    Vacuum Tube LEDs - unstuck foam tape
    Vacuum Tube LEDs – unstuck foam tape

    Replacing it with my now-standard black 3M outdoor rated tape ought to solve the problem forever more.

    For whatever it’s worth, the SK6812 RGBW LEDs have had exactly zero failures in the last two years or so; I finally turned off the test fixture.

    Before reassembling the light, I plugged the USB cable into the bench supply and watched the Nano reset erratically. Careful poking showed the USB cable was intermittent, so I carved it up:

    Failed USB cable - autopsy
    Failed USB cable – autopsy

    As far as I can tell, the black wire (supply common) was cut mostly all the way through, with just a few strands remaining, before I peeled the insulation back.

    A closer look at the solder joints doesn’t inspire much confidence in their QC:

    Failed USB cable - solder joints
    Failed USB cable – solder joints

    If those pads tarnished along with their solder blobs, the overmolded plastic isn’t the right stuff for the job. If they started life like that … ick.

    I must up my cable spend, although I have no confidence doing so will improve the quality.