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Unread 11-04-2009, 17:01
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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Re: What Happens When Metal Gets Into A Jaguar (SMOKE!!!!)

Gary,
I have seen enough failures to recognize a metallic short as a cause in many failures in either Jag or Victor. The good news is both controllers have FETs that are capable of higher currents than we demand. Although there is some good protection of the boards, a metallic fragment or a lot of filing dust causes a nice path between the gate and source. That said, the Jaguar one direction only failure is not one of these that appears to be caused by metal. The gate driver chip is failing without a FET failure. Everyone should remember that the fan blows down against the FETs so any metal on the top gets moved by fan action. In the Jaguars, the fan runs whenever there is an output and for up to 10 seconds after the command ends. The Victors run all the time.
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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.
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