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Unread 12-01-2012, 18:17
Unsung FIRST Hero
Al Skierkiewicz Al Skierkiewicz is offline
Broadcast Eng/Chief Robot Inspector
AKA: Big Al WFFA 2005
FRC #0111 (WildStang)
Team Role: Engineer
 
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Rookie Year: 1996
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Re: Banebots RS-775 Case Short

J,
What you describe is exactly what will happen with the Crio shorted to frame. It will only occur when the motor is run in one direction. What occurs is that the motor drive signal is opposite polarity to the power input to the Crio. When the motor is turned on in that direction the motor voltage bucks the Crio power supply through the #18 AWG wiring causing the Crio to reboot. The resulting voltage is less than the Crio minimum power input of 19 volts. If the Crio didn't reboot (disabling all outputs) the resultant current path would eventually burn open the #18 wiring. If you had mounted the Crio on an insulated mount, it may have shifted so that the chassis contacted robot frame or something was pushed against the Crio mounting hardware from underneath. When another official I looked into your robot during finals, I did not see anything obvious. I did not turn it over and look at it from underneath. It is also possible that when your arm moved, a wire was pinched in the mechanism and it was not the fault of the motor at all.
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Good Luck All. Learn something new, everyday!
Al
WB9UVJ
www.wildstang.org
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Storming the Tower since 1996.