jcb JS200 Service Manual page 122

Electrics
Section C Section C
4 - 2 Engine Control 4 - 2
Stepping Motor (continued)
Driver Circuit (driver)
The driver circuit of a stepping motor consists of a logical section which forms and distributes a pulsed signal from an oscillator
and an amplifying section which amplifies and supplies the signal to the motor.
Stepping motor principle (if 1st - phase is on drive)
The wound phases of A, B and C are rolled on the stator.
When a pulse enters A phase, rotor is in (1) condition and A-a, A-c are energised. The excitation of A phase breaks down and
then the pulse of B phase enters, B-b, B-d are energised and results in (2) condition. When the rotor rotates in a counter
clockwise direction it sets up the condition (A-B-C). When a pulse is registered in the order (C-B-A) the rotor is rotating
clockwise.
9803/6400 Issue 1