I have recently received a RC car from Hobbyking, the 1/10 Quanum Skull Crusher 2WD Brushless Monster Truck, very powerful, very fast and it actually roars like a monster. Comes with a 35A (190A burst) brushless ESC and a 3650 size 2700KV brushless inrunner motor, these parts are getting very hot when running (and the ESC needs an extra cooling fan).
During a run, the ESC accidentally fails. The motor just flips back and forth rapidly and can not make a full rotation, which suggests one of three phases fails.
A quick check reveals that the “red” phase has no output, i.e. when disconnecting black or yellow phase the motor stops, but disconnecting the red phase the problem repeats. Maybe the MOSFETs for that phase are dead. Time to open it up!
The picture shown here is the backside of the ESC, which has 6 MOSFETs (4833N 191A Power MOSFET), 2 for each channel. Using a multimeter (diode test mode, first touch the red lead at the Gate then touch the Drain while keeping the black lead one at the Source), all 6 MOSFETs appear functioning correctly. However the continuity test between the red phase’s transistors to the red cable reveals that the connection is open, somewhere in the middle of the PCB. So the quick fix is to attach a wire between those to points, and yayyyy IT WORKS!
And the monster now can roar up and high again.
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