Sorry to ask off topic but this group is the most knowledgeable in all things geeky ;-)
Please read this using a fixed font so the ascii timing diagram is correct. I am trying to rebuild a damaged bldc motor It had built-in controller, and water damage blew fet traces right off the pcb. The pcb also had 3 hall sensors SS41 and the rotor has a ring magnet. A quick check showed the halls could still be energized and output 5V signals. I brought the UVW coil wires and the Hall wires out for a new external bldc drive. But when I tested the halls closely I saw the nice 3 phase ripple wasnt continous for 360 mechanical degrees. I repeated checking many revolutions and saw a repeating failure in 3rd of 4 quadrants of the magnet ( 4 cycles to 360 mech degrees ) I think I need to replace the ring magnet. Has anyone here any advice ( besides buy a new 400$ motor ? :-) I've asked the manufacturer but they seem out of business since 2015 here's the letter to the mfctr... Hello Please read this using a fixed font so the timing diagram is correct. I have a cyclone motor with built in control. I have water damage and fets blew damaging the pcb. I have little money, so I try to fix. I examined and see the HALLs still work and decided to use an external BLDC drive. I cleaned the motor and bring out new UVW and Hall and 5V/gnd for halls. I applied 5V and use 10Kohm pull up on each hall output, then record the signal as I turn the motor by hand thru each detent (cog) for 360 mechanical degrees. The motor shaft can be turned by hand and has definite positions where the magnets hold the shaft. I call these positions 'cogs' or 'detents'. I tested the outputs of the hall sensors at each cog of the motor turning CW. There are 24 positions in 360 degrees of motor shaft ( no gearbox connected ). There are 4 cycles of the Hall pattern in 360 degrees. Each 90 degree cycle has 6 'cogs'. The halls actt differently in quadrant 3 of 4. I suspect the magnet is damaged cog count hall 1 2 3 4 5 6|1 2 3 4 5 6|1 2 3 4 5 6|1 2 3 4 5 6| <-- 4 sets of 6 cogs is 360 mechanical degree _ _ _ |_ _ _ | _ |_ _ _ U |_ _ _| |_ _ _ _ _ _| |_ _| |_ _ _| 3 3 | 3 6 1 2 3 3 not 3 3 3 3 3 3 3 3! the 3rd set is wrong | | | _ _ _ | _ _ _ _ _ _ _ V _ _| |_ _ _| |_ _ _ _ _| |_ _ _| |_ ..2 3 3 3 5 1 3 3 1.. again 3rd set is wrong | | | _ _ _ _ _ _ _ _ _ _ W |_ _ _| |_ _ _| |_ _ _ _ _| |_ _ _| ..1 3 3 3 3 5 1 3 2.. again 3rd set is wrong | | |
|<----NG----->| 3 small signals
since this repeats in many tests and the 3rd quadrant is always different I think the magnet ring is damaged ( depolarized almost ) in that quadrant. Can I get a new magnet? Can I repair the magnet? Does the magnet need aligning?
Sorry for the complex question, hope you can help me. Thanks Tom Powderly
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