When I plugged the LCD into the RAMPS board, the USB current jumped from 70-ish mA to about 700 mA, which seemed odd. Eventually the problem followed the “Smart Adapter Board”, which has no active components and simply rearranges two pin headers into two ribbon cables, so what could go wrong?
This stared me in the face for a while until I recognized it:
Yup, that trace is supposed to run around the corner without merging into the ground plane and, of course, it carries the +5 V power supply to the LCD board. Just another production goof and, I’m certain, the boards don’t get any testing because they’re so simple.
Two cuts, a bit of scraping, a snippet of Wire-Wrap wire, and it’s all good:
The white-on-blue display is reasonably legible in person, even if it’s nearly invisible here. Might have something to do with polarization vs. the Pixel’s camera.
Everything else on the LCD board works fine. I set the beep to 50 ms and the tone to 700 Hz, which suit my deflicted ears better than the defaults.