The ↓ (“down”) button on one of our lift chairs stopped working, although the ↑ (“up”) button worked fine and, as you’d expect, verifying this problem left the chair in a rather awkward position.
The usual power cycle and unplugging / replugging the control had no effect.
This control is the one I couldn’t pry apart to dim its LEDs, so I tried various combinations of pins until this scribble emerged:
I have no idea of the correct pin numbering, but the scribble looks into the connector pins with the keyway on top:
The more intricate control for the other Pride lift chair has only four pins in its connector, so I couldn’t just swap them to see what happened.
The polarities are for the continuity / resistance test probes.
The takeaway: The two buttons did similar things to two different connector pins, so the control seemed to be working correctly and the fault lies elsewhere.
The control sports a USB jack for powering / charging your favorite device and I’m reasonably sure the control has a microcontroller tucked in there for good reason, implying the circuitry is surely more complex than maybe a rectifier bridge and some resistors.
So I shoved the chair into the middle of the room, deployed some test equipment, reconnected the control, plugged the chair power supply into the outlet strip, and … of course both buttons worked perfectly.
Soooo the chair is back in place and we’ll see what happens next.
Speaking of Heisenbugs, the HQ Sixteen continues to work fine, too.
The Smell of Molten Projects in the Morning 