2.3.4 CR Motor Driver Circuit
TheCR motor drivercircuit is shown below.
Thecarria gemotor drivercircuit controls theCR motor, using an open-loop, constant drivearrangement. 2-2
and 1-2 phasesexcite themotor. A 2-2 phasestep is equivalentto a 1-2 phasestep doubled. Ports 1 to4 of
theSLA7024M are usedto change theexcitation phase, dependingon the selectedprint mode. Table 2-8
describesthe motor driver modes.
Table 2-8 CR Motor DriverModes
Speed Mode Print Speed
(CPS)
Drive
Frequency
(PPS)
Excitation
Phase Applications
8/3 440 5280 2-2 Super Draft
2 330 3960 2-2 Draft
16/9 293.3 3520 2-2 Super Draft and Copy 2
50/33 250 6000 1-2 Bit imageand head hot
mode
4/3 220 5280 1-2 Super Draft, Draft, Copy 2,
and Power down
1 165 3960 1-2 NLQ,Draft, and Power down
25/33 125 3000 1-2 NLQ, Super draft, Copy 2,
and Power down
2/3 110 2640 1-2 NLQ, Draft, Copy 2, and
Power down
1/2 82.5 1980 1-2 NLQand Power down
1/4 41.3 990 1-2 NLQ, Copy 2, and Power
down
TheSLA7024M (IC12) CR motordriver circuit detects andregulates the amount of currentflowing inthe
carriage motorcoil. Thecurrent flowing throughthe coil varies, dependingon thespeed of the CRmotor.
TheCPU sets the amount of currentvia the Address /Dataline. Signals are sentto ports 3 (RFA) and14
(RFB) of theSLA7024M. The SLA7024Msets the coil current, dependingon the CR speed.
CPU CR A
CR-A
CR B
CR-B
Gate
Array
IN A
IN B
IN-B
6
5
17
16
IN-A
1
2
3
4
PG00
PG01
PG02
PG03
R73
R74
R75
R76
+5V R72
C31
R68
R67
C29, 30
R71 R69, 70
RFA
RFB
RSA
RSB
GND A
GNB B
A
-A
B
-B
3
14
9
10
4
15
CRI0
CRI1
CRI2
CRI3 62
63
64
65
+35V
CRCOM
SLA7024M
Address
Data Line
Figure 2-35 CR Driver Circuit
FX-2170 ServiceManual Operating Principles
Rev.A 2-25