Easy way to test a 4 pole, 3 phase brushless motor?

Thread Starter


Joined May 21, 2018
I'm working on a piece of lab equipment with the 57BL116 motor listed on this datasheet. The device works perfectly except that the motor never begins running. I've tested the power supply under load and found it to be fine so assumed the issue was likely with one of the FETs on the control board since I've seen that a lot in the past. After replacing the board the motor still doesn't run. Occasionally it will twitch slightly on startup, but that's it. I'm wondering what I may be able to do to confirm the motor is bad since it will likely be pretty expensive to replace. I've tested the resistance between the different coil points and they seem more or less normal, definitely not failed open at the least, but Im not sure what else to try since running these motors takes a fairly complicated circuit. What are the odds a failed hall effect sensor inside would lead to total failure of the motor to move vs just erratic movement? Also, it seems the odds of a hall effect sensor failing are lower than most things, but maybe that's not the case? Thanks in advance for any ideas!


Joined Jul 18, 2013
You can test the hall devices manually by supplying the correct power to them and rotating the armature, use a meter or a scope to see each pulse as rotated.
Also the stator and halls timing can be seen on a double beam scope, if you have one by back feeding the armature by external means, another motor or hand drill etc at about 200rpm.
see PDF.