Service manual
Operating Principles
DEX-5000+
Service Manual
Carrige
transfer direction
3
t
““””””””””-””””-
SP2
1
Carrige
transfer direction
[
Right
~
Left
t
3
‘“---””””””--”””
SP2
1
Figure 2-26. Measurement Sequence
2.3.5 PF Motor Driver Circuit
Stepping motor driver
SLA7026
(IC1l)
drives the
PF
motor. Figure 2-27 shows the
PF
motor driver
circuit block diagram, and Table 2-6 provides the
PF
motor specifications.
Gate Array
E05A87
(IC7)
PFI
Ref. voltage
setting circuit
(Q23)
I
I
PFA
CPU
TMP96C141
(ICI)
PGOO
A
I
‘GO’~
\
‘“3t-----
SLA7026
(ICI 1)
r+
&
4.7 VDc
ANA
A~
PFA
I
/lN-A
-A
1=
PF B
ANB
B
PFC
IN-B
-B PF D
I
<<
cnoY
*a
-.J
=P
Figure 2-27. PF Motor Driver Circuit
The motor pulse switching signals are transmitted from CPU ports
PGOO
to
PG03.
The
PF
motor is
controlled using open-loop phase switching based on the specified time data, and the phase
driving method is 1-2 phase excitation. (When the
PF
motor is held, the phase driving method is 2
phase excitation.) The CPU selects the most suitable driving mode from the modes below
according to conditions such as the paper feed step number and the pull tractor condition.
D
Micro feed (adjust) mode
LI
Normal speed mode
Q
Middle speed mode
Each phase switching FET in driver
IC1l
is an open collector. When the phase switching data is
HIGH, the motor is turned on. The
PFA
port of the gate array monitors the phase A signal of the
PF motor and checks whether it is operating normally. The
PFA
port is used as the WDT (watch
dog timer). If PF motor operation is abnormal, the gate array outputs the
RSTOUT
(reset request)
signal to the CPU and the +5 V system reset
IC
(IC9).
2-30
Rev.
A