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Unread 16-02-2011, 09:22
Jim Wilks Jim Wilks is online now
Electrical Engineer
AKA: Jim Wilks
FRC #1360 (Orbit Robotics)
Team Role: Mentor
 
Join Date: Feb 2008
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Location: Oakville, ON
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Re: Banebots RS-775 Case Short

We had 2 of 5 motors with case shorts. One was 1k ohm and the other was about 2 ohms. We applied 12VDC from a current limited power supply set for 25A max. On the 1k ohm motor, the problem cleared immediately. The 2 ohm motor let loose with some nice blue sparks, but then was good.

We remeasured both motors and both still had some high resistance (~20K ohms) to ground. We than ran each motor for a few minutes while applying + to the case. We then repeated this with - to the case. Both motors are now showing >20M ohms. I guess that's a fix!

No debris was seen at any point in the proceedings.

However, I must echo the points above about being careful when doing this as a short which does not clear could be very dangerous, particularly if your voltage is not current limited to a "safe" level.

Banebots has really "missed the boat" on this years offerings to FIRST.

JW