The motor in the hard drive is a three-phase AC motor, with three wires, with four wires. The coil connection mode is star. The 3-wire is used to seal the neutral line inside the motor. This is the neutral line for a 4-wire. And this kind of motor is hall-free, relying on the surge of U,V,W3 coils to measure speed and self-test phase.
The hard drive has a drive chip on it. Because the hard disk motor belongs to a precision motor. Very high speed requirements. So most of the driver chips are programmed to turn.
If you want to drive this motor, you can't use the chip on the original hard drive.
1, can use a single chip computer to do a phase shift circuit to achieve
2, can be driven by the driver chip on the optical drive. If there is no Hall, the chip on the optical drive only needs to short-circuit the corresponding signal line to drive the three-phase motor.