If you are going to power a LED from USB, remember to put an appropriate resistor in series with the LED to limit current.

Looks like a QFN-20 package to my untrained eye but beyond that no idea.

On version 6, activating High Contrast twice (pressing H on default keybindings) actually hides the other layers completely. So it's now a tri-state (normal-dim-hide).

Maybe you are just in an EM field which triggers it? Have you tried to troubleshoot with a multimeter?

The make, model and year of manufacture for the radio would probably go a long way here...

Doing this fully in the analog domain certainly has a beauty to it but from the practical and especially v2.0 development perspective I'd definitely drop a microcontroller in there. You can also apply correction curves, calibration etc very easily with one.

Any idea why this arrangement i.e. how does the main winding in series with the cap affect the auxilliary winding? Also, I am reverse engineering this to implement a replacement speed control, the original PIC microcontroller seems to be dead. So I am wondering about start-up sequencing mainly to make sure I don't fry the motor.

@TonyStewartEE75 my searches before posting indicated that a start cap for a 250W motor should be somewhere in the 60-80uF range which is 10x more than what's in the circuit. Or does the multi-speed nature of the motor somehow play into this is and the start cap can be much smaller?