Toshiba e-studio550 Service Manual page 181

<Control signals>
(1) DEVCK signal (LGC DEV-MOT: input)
This signal is a reference clock signal for the developer motor to rotate at a fixed speed. The frequency
of the reference clock is 821.2Hz.
When the cycle of the FG pulse deviation from the reference frequency is within +6.25%, this state is
specified as lock range (normal rotation). Also, at this time, the LED "D4" light comes ON.
(2) DEVON signal (LGC DEV-MOT: input)
This signal is the motor ON/OFF control signal. When it becomes "L" level, the motor rotates.
Signal level for motor circuit
Signal "H" level "L" level
DEVCK Reference clock (821.2Hz)
DEVON Motor OFF Motor ON
e-STUDIO550/650/810 DEVELOPER UNIT 12 - 8 JUNE 2002 © TOSHIBA TEC