So, we had our monthly Repair Cafe (in #Regina, #SK, #Canada) on Saturday. Geez, how did almost a week go by before I got to write this up...
At my table, there was the usual assortment of electronics and small appliances (containing electronics in most cases...). In many of those, after testing every common mechanical, electrical, and sensor failure, the problem was narrowed down to the main logic board. And every testable component on those boards tested fine, and there were no physical signs of problems (leaky caps, soot marks, etc). Almost certainly a failed microcontroller or its support circuitry.
So frustratingly, the answer in those cases is "The board is bad, it's specific to this model (or some small number of similar models), it can't be ordered from the manufacturer and would cost too much if it could, the best you could hope for is to find someone selling one ripped out of another unit, but that one's probably being stripped for parts because the board went bad in that one, too". So off to the landfill these items will probably go.
It's annoying. In many cases, there's an obvious design flaw that leads to these early, unfixable failures.
Some fixes, and one interesting case. A portable dog toy thing that wouldn't take a charge at all - but probing around its logic board appeared to kick its battery-management system into life (due to the tiny current from the meter I was using) and it started charging. I hope it worked once charged.
#RepairCafe