Hall sensors · BLDC and EV motors

Hall sensor repair and alignment for BLDC motors

Brushless DC motors in fans, pumps, compressors, conveyors and EV hub motors use three Hall sensors to tell the controller where the rotor is. A failed or shifted Hall sensor makes the motor stall, vibrate, draw high current or run in one direction only. We test the Hall sequence, replace failed sensors and align the Hall board to the motor's back-EMF.

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BLDC blower motor being tested with a tachometer

Repair turnaround you can plan around

Send a photo of the nameplate first. We confirm whether the motor is repairable, and the quote, the same working day.

Emergency: same day

For a line-down motor, where the fault and parts allow. WhatsApp us before you send it so the bench is kept free.

Urgent: 3 working days

Repair, encoder alignment and test, counted from the day the motor reaches the bench and the quote is approved.

Standard: 7 working days

Full repair, encoder alignment, run test under load and a printed test report.

Free repairability check from a nameplate photo
Printed test report with every motor
Written warranty, terms stated on every quotation
Pickup can be arranged; parts that must be imported are quoted with their own timeline

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01Checks

What we check

Check	Good result
Hall supply	Rated voltage, typically 5 V, up to 24 V on some industrial motors
Output switching	Each output switches cleanly, no stuck or noisy line
Sequence	Six valid states per electrical cycle, no invalid 000 or 111 state
Spacing	60° or 120° electrical, matching the controller setting
Alignment to back-EMF	Hall edges line up with the zero crossings of the motor's generated voltage
Run test	Smooth in both directions with normal current

02Applications

Motors we work on

EC and BLDC fans and blowers in HVAC, cleanrooms and data centres
BLDC pump and compressor motors
Two- and three-wheeler EV hub and mid-drive motors
Industrial servo motors with Hall and tach feedback: Siemens 1FT5, Indramat MAC, Baldor, ABB PH, SEM HD and HJ, Kollmorgen Seidel SM56
BLDC motors on textile, packaging and lab equipment

03Related

A board that powers up is not the same as an aligned motor. Our article on EC and BLDC vibration after a board swap explains why. For new motor designs, see choosing feedback for a new motor.

04FAQ

Hall sensor questions

How can I tell if a Hall sensor has failed?

With the controller disconnected and the Hall supply on, turn the rotor slowly by hand and watch the three outputs. Each should switch cleanly between high and low, and together they should step through six states per electrical cycle. A line stuck high or low, or a missing state, points to a failed sensor or wiring.

What is the difference between 60° and 120° Hall placement?

It is the electrical spacing between the three sensors. The controller must be set for the same type; 120° is more common. A 60° motor on a 120° controller will not run correctly.

My BLDC motor vibrates after a controller or board change. Why?

The new board may be fitted a few degrees off, or set for the wrong Hall pattern. The Hall edges no longer line up with the back-EMF, so commutation is early or late. Realigning the board usually fixes it.

Do you repair EV hub motors and controllers?

Yes. We repair two-wheeler and three-wheeler BLDC hub motors, including Hall sensors, and their controllers at component level.

Free downloads for your maintenance file

Printable one-page sheets from our bench. More on the resources page.

Motor feedback selection guide

For motor makers and machine builders: Hall sensors, incremental encoders, absolute encoders and resolvers compared on cost, resolution, temperature, noise immunity and drive compatibility.

PDF · 1 page · 4 KB · free, no sign-up

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Encoder alignment checklist

What to record before removing an encoder, the order of checks after refitting it, and the readings that tell you commutation is right before the motor goes back on the machine.