Epson Stylus PHOTO 2000P Service Manual page 51

EPSON Stylus PHOTO 2000P
PTS (Print Timing Signal) production
The circuit produces PTS signal (cycle: 1/360 inches) by dividing
waveform cycles of Phase A. The print timing signal is used to eject
ink at a correct timing.
1/180"
Phase A Phase A
Phase B Phase B
1/360"
Figure 2-18. Print Timing Signal and Linear Encoder Phase A
OPERATING PRINCIPLES
PF motor driver circuit
A DC motor is used as the PF motor in this printer. In addition to the CPU
and ASIC, a slave CPU is mounted on the C304MAIN board. Since the
slave CPU is exclusively used to control DC motors, it reduces duty of
CPU and ASIC to offer faster data processing. The block diagram for the
PF motor driver circuit is as shown below:
CN12
PE Encorder
Slave CPU (C90A26CA) controls paper feeding amount by referring to the
encoder pulses sent from ASIC (IC18). It sends a proper drive current
value to the motor driver. Based on the control signal from the slave CPU,
the motor driver (IC19) outputs drive current to the PF motor.
Unlike a stepping motor, this DC motor can not detect paper feeding
amount by referring to the pulses given. For this reason, a loop scale is
Electrical Circuit Operating Principles
IC8
IC15
E05B70CD
C90A13CA
ENA
NMI
CRPHAA
NMI
CRENBA
RD1
P31
ENB
TD1 P33
CRBI3 P32
CRPHAB
P30
CRENBB P64
CRAI2 RES
MD2
P17
P15
CRBI0 P20
P21
CRAI3
CPU
P25
Figure 2-19. PF Motor Driver Circuit Block Diagram
Revision A
42V
SCON
IC19
A3958SB
C116
MODE
PD3
0.22U
PHASE
PD1 OUTA PF-A
PF-B
OUTB
PD0 ENABLE
C119
0.22U
CP1
PD4 RANGE
CP2
REF
C120
022U
VREG
OSC
PD6 SENSE
CLOC
C137
0.1U
GND
DATA R113
PD5
GND
0.24
GND
STOROBE
PD7
-
R138
IC24
DA0 4.4B
M62552FP
R139
4.99B
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