Today's act of divvery was a modern classic. I was poking around inside the electric fan that lives in our bedroom. A relatively posh model with an electronically controlled DC motor that goes down to almost-silent, IR remote control that's frustratingly directional, silly
BLUE LEDs, etc.
I was so amazed discover the control board connected to the fan driver board by a 4-pin cable marked '0V' '5V' 'TX' and 'RX' that I momentarily forgot
Oscilloscope 101. A bang and a flash later, and I'm sitting in a dark room with the fire alarm beeping and barakta asking if that was supposed to happen.
With power restored, I resignedly work my way along the trail of blown fuses to the inevitable dead semiconductor. Astoundingly, this turned out to be a pair of M7 diodes, and not some unobtanium MOSFET or microcontroller. Even more astoundingly, I have a 50 of the things in a selection box of Chinesium diodes I purchased a couple of years ago, so was able to replace them. Powering up the controller board with everything else unplugged did not result in further light-emitting fuses or the release of magic smoke. For good measure I checked that the
FULL BRIDGE RECTIFIER was functioning properly by sticking my sweaty finger across the reservoir capacitor.
Once I'd regained sensation in my hand, I confirmed everything now worked, and spent some quality time reverse-engineering the comms (with the benefit of an isolated power supply). The fan is now reassembled, with all screws accounted for, and programming an ESP to man-in-the-middle the communications is now left as a project for Future Kim, when normal karma and divvery levels have been restored.