User manual

95.08.23.11.29
Color LaserWriter 12/600 PS Basics & Theory 1–39
Scanner Motor
Circuit
The scanner motor is a three-phase, 8-pole DC brushless motor with a
hall element. It is incorporated in a single unit with the scanner driver
which controls it so that the motor rotates at a constant speed. When
the printer is turned on, the oscillation frequency of the crystal oscil-
lator (X103) is divided by the gate array (IC109) and the resulting
signal is sent as the
SCNCLK signal to the scanner driver. When the
/PRNT signal that is sent to the CPU (IC101) on the DC controller goes
“L,” the CPU sets the
/SCNON signal to “L” via the gate array and
rotates the scanner motor. When the scanner motor reaches the specified
speed, the scanner motor ready signal (
/SCNRDY) goes “L.” The CPU
on the DC controller issues the print sequence command to the CPU on
the mechanical controller when the
/SCNRDY signal goes “L.” The
CPU on the DC controller monitors the
/SCNRDY signal via the gate
array to determine whether or not the scanner motor is rotating at the
specified speed. If the scanner motor fails to reach the specified speed
within 30 seconds after it starts rotation, the CPU will stop it and notify
the I/O controller of this scanner failure.
CPU
(IC101)
Gate
Array
(IC109)
/PRNT
SCNCLK
+24V
J102-10
J108-29
J102-11
J102-9
J102-6
J102-8
X103
9
/SCNON
/SCNRDY
+5V
J102-5
J102-7
10
148
66
138
DC Controller Board
Scanner
Driver
M