Epson 2080 - LQ B/W Dot-matrix Printer, Service Manual

Page: 27 / 55

LQ-2080 Revision A
Operating Principles Control Circuit 27
2.3.3 CR Motor Driver Circuit
The CR motor driver circuit is shown below.
Figure 2-6. CR Motor Driver Circuit
The carriage motor driver circuit controls the CR motor, using an
open-loop, constant drive arrangement. 2-2, 1-2, and W1-2 phases
excite the motor. A 2-2 phase step is equivalent to a 1-2 phase step
doubled. Ports 1, 8, 11, and 18 of the SLA7024M are used to change
the excitation phase, depending on the selected print mode. Table 2-2
in the following page describes the motor driver modes.
The SLA7024M (IC11) CR motor driver circuit detects and regulates the
amount of current flowing in the carriage motor coil. The current flowing
through the coil varies, depending on the speed of the CR motor. The
CPU sets the amount of current and signals are sent via ports 32 to port
35. The SLA7024M sets the coil current, depending on the CR speed.
C P U ( I C 4 )
P G O 0
P G O 1
P G O 2
P G O 3
1
2
3
4
6
5
1 7
1 6
/ I N A
/ I N - A
/ I N B
/ I N - B
A
- A
B
- B
S L A 7 0 2 4 M ( I C 1 1 )
C N 1 1
C R A
C R - A
C R B
C R - B
8
1
1 1
1 8
1
2
3
4
R F A
R F B
3
1 4
G A ( I C 3 )
C R R F A 0
C R R F A 1
C R R F A 2
C R R F A 3
1
2
3
4
R 1 2 2 - R 1 2 5
R 1 1 6 - R 1 1 9
C R R F B 0
C R R F B 1
C R R F B 2
C R R F B 3
1
2
3
4