Epson Stylus 1500, Service Manual

Page: 62 / 185

Carriage Motor Driver Circuit
The SLA7043M carriage motor driver IC (IC15) outputs a constant current to drive the carriage
motor. The E05B16 gate array (IC2) determines the motor phase and speed and then sends a signal
to the carriage motor driver IC using the 4-bit serial transmission line.
The first bit indicates the motor rotation direction. The other three bits are current duty data for the
motor speed of each printing sequence. The SLA7043M motor driver can select the reference
voltage based on these three bits of current duty data. It also receives these signals by two serial
transmission lines for the two motor phases (A and B). As a result, the carriage motor can drive in
micro-step sequences (a minimum of 1/720 inch).
The SLA7043M motor driver reads the 4-bit data using four clock counters from the E05B16 (IC2)
clock. Each bit is read at the falling edge of these clock pulses. As a result, received serial data is
placed in the shift register and then shifts the latch register. When the strobe pulse becomes active
from the E05B16 (IC2) clock, serial data is moved into the reference voltage selection circuit and the
voltage is changed. Therefore, when the printer is in constant-speed mode, this strobe pulse
becomes inactive.
E05B16
(IC2)
S L A 7 0 43 M
(IC15)
R E F A
R E F B
3
14
80
101
102
CRV
CR A
C R _ A
CR B
C R _ B
A
B
11
18
5
16
2
+5 V
C L K B
13
X CR CL K
81
X CR S T B
D A TA A
D A TA B
8
1
C R C O M
+42 V
6
17
C R V 0
~ C RV 6
CR AS ERI
CRBSERI
CR Mo tor
C L K A
STBA
STBB
B
A
Figure 2-24. Carriage Motor Driver Circuit Block Diagram
Operating Principles
EPSON Stylus 1500 Service Manual 2-21