Registered: 1443021001 Posts: 184
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I saw a new (to me) failure mode for Cortex at Dallas BEST Game day.
Symptoms: - "Robot drives funny" since one wheel is under powered - Robot on jackstand so wheels can spin, drive forward, and hold wheel back by hand ** wheel on port 2 stalls and shakes; Other wheel on port 9 is pulls harder until it stalls. Diagnosys: - Changing motors didn't change behavior, so its not the motor - Same behavior both forward and backward wheel rotation, so it isn't just half-bad Hbridge. - Changing MC29 controllers didn't change behavior, so its not the Hbridge at all - Swapping wheel motor ports from 2 to 9 moves problem to other wheel, * Problem is on port 2; Hypothesis: port 1-5 thermal fuse is tripping too quickly. - Additional tests not yet performed: try other ports on that fuse, ports 1,3,4,5 Workaround: swap out cortex for a different one, Lesson Learned: always have your programming computer ready to program a spare cortex, since a spare cortex without your program is nearly useless.