A friendly reminder to protect your electronics from dust/shavings/etc!
A pair of power distribution boards was returned for failure analysis - both failed at competition in ways that severely affected the match outcome. In the unit pictured, the 12V boost regulator was not boosting, and instead passed battery voltage (minus a diode drop) to the radio. This “works” fine until the battery voltage sags and reboots the radio, taking the robot out of the match for many seconds.
When I opened the board I found many forms of swarf, including metal dust, wire clippings, wood shavings, hair, and onion skin. There were at least 3 candidate short circuits caused by swarf, though it is impossible to be certain which fault was active as they can move during shipping or during game play.
This is a rev 4 - the original shipped version. More recent versions have a protective conformal coating, which reduces but does not eliminate this problem. The other returned board was this year’s version, and shows signs of swarf interference.