Rev.D
Product Overview Appendix D-57
TM-U675/U675P (with autocutter) Service Manual
Confidential
Carriage Motor Drive Circuit
The carriage motor for this printer is a two-phase stepping motor. Constant-current drive is
provided using 2-2 phase excitation as the drive method. Therefore, a dedicated constant-
current drive chopping driver (U14, A2917SEB made by Alegrow) is used.
Figure D-53
Since the driver is of the constant-current type, the motor can be directly driven by setting the
peak current. The peak current is set as described below, using the logical level of terminal I0
and I1.
At this time, VREF uses the DA output of the CPU (U3), and is set to an arbitrary value (0 - VCC)
by firmware. RS is the resistance value (0.68
Ω)
of R78 and R101. Accordingly, the current to the
motor is calculated by the logic level of I0, I1 (judged by VREF1, 2 terminal voltage).
Table D-10 Logical level of terminal I0, I1 and output current
I0
I1
Output Current
L
L
VREF / (10
×
Rs)
H
L
VREF / (15
×
Rs)
L
H
VREF / (30
×
Rs)
H
H
0
24VC
VCC-PWR
M
CR_B-
CR_B-
CR_A+
CR_I11
CR_B+
CR_A-
CR_PH2
24VSW1
CR_I10
CR_PH1
CR_A+
CR_DA
CR_I21
CR_I20
CR_A-
CR_B+
R97
R83
Q18
U14
OU
T1
A
6
E1
5
SEN
SE1
4
OU
T1
B
3
I1
0
2
I1
1
1
VR
EF
1
44
PH
ASE1
43
EN
ABL
E1
42
RC1
41
LOGIC
S
P
LY
40
OU
T2
A
18
E2
19
SEN
SE2
20
OU
T2
B
21
LO
AD
SPL
Y
22
I2
0
23
I2
1
24
VR
EF
2
25
PH
ASE2
26
EN
ABL
E2
27
RC2
28
G
29
G
30
G
31
G
32
G
33
G
34
G
35
G
36
G
37
G
38
G
39
G
17
G
16
G
15
G
14
G
13
G
12
G
11
G
10
G
9
G
8
G
7
C45
R99
R78
R81
C126
R100
C47
D19
D18
D14
C48
D15
C46
R101
C36
C34
Summary of Contents for U675 - TM Color Dot-matrix Printer
Page 2: ......
Page 4: ...Confidential ii Revision Table ...
Page 34: ...1 22 Troubleshooting Rev D Confidential ...
Page 168: ...2 134 Assembly and Disassembly Rev D Confidential ...
Page 180: ...Appendix A 2 Service Tools and Lubricants Rev D Confidential ...
Page 270: ...Appendix D 82 Product Overview Rev D Confidential ...
Page 322: ...Appendix J 2 Screw Types Rev D Confidential ...
Page 324: ...Appendix K 2 Parts Layout Rev D Confidential Main Circuit Board Unit Solder Side memory board ...
Page 325: ...SEIKO EPSON CORPORATION Printed in Japan EPSON ...