User manual

95.08.23.11.30
Color LaserWriter 12/600 PS Basics & Theory 1–108
Drum Motor
Drive Circuit
The drum motor is a two-phase stepping motor controlled by the drum
motor driver (Q2002) on the mechanical controller. It drives the photo-
sensitive drum and the transfer drum.
Upon receiving the print sequence command, the CPU (Q2001) in the
mechanical controller sends the drum motor control signals (
DRMPHA,
/DRMPHA, DRMPHB, and /DRMPHB) and the drum motor rotation rate
select signal (
DRMICH) to the drum motor driver (Q2002) 0.2 second
after the main motor starts. The Q2002 sends the drive signal to the
drum motor based on these signals. 24 VC power supply is used to
drive the drum motor. In order to slow down the paper feed speed
through the fuser assembly in the transparency mode, the CPU sets the
DRMICH signal to “H” to drive the drum motor at a low speed. If the
transfer drum top sensor signal (
TOPREG) remains unchanged for six
seconds or more (12 seconds in the transparency mode), the CPU
recognizes it as a drum motor error.
Mechanical Controller Board
J2015-1
-2
-8
-4
-5
-6
+24 VC
AO
/AO
BO
/BO
COMA
COMB
Drum Motor
12
8
1
11
18
7
6
5
16
17
(Q2002)
(Q2001)
CPU
Drum
Motor
Driver
DRMPHA
/DRMPHA
DRMPHB
/DRMPHB
DRMICH
47
52
51
50
49
M4
TOPREG
PS8
Transfer Drum
Top Sensor
+5V
14
3