Drivers; Pf Motor Driver - Tally Dascom 7010 Series Maintenance Manual

2-2. Operation of Control Parts

2-2-4. Drivers

(1) PF motor driver

This is a driving circuit to drive the PF Motor (stepping motor). The following illustration shows
a simplified circuit. The PF Motor is driven by the unipolar constant current chopper method.
The exciting method for the motor is the 2-phase method.
The power to the PF Motor is supplied by turning ON the FET Q4. This is accomplished by
activating the monostable multivibrator U16A. When U16A is triggered, Q5 turns ON and FET
Q4 turns ON. (TEMPOFF signal is normally at "High". If the PF motor temperature rises
excessively, TEMPOFF signal goes "Low" and the output from U16A is inhibited. Thus, +24V to
the PF Motor is shut off. For TEMPOFF signal, refer to 2-2-3
sensor".)
PFMA, PFMA, PFMB and PFMB signals are the exciting pulses to drive the PF Motor.
The digital-to-analog converter (U4) is used to control the PF motor current by applying its
output to pins 3 and 14 (REFA and B) of the motor driver (U18).
From U1 CPU
From U14 Custom IC
From U1 CPU
From PF Motor Temp.
Sensor Circuit
TMPOFF
DACIN
From U1 CPU
DACCLK
CS_DAC
From U14 Custom IC
U16A
Monostable
Multivibrator
PFCLK
1
13
Q
A
PFON
2
B
GRESET
3
CLR
74VHC123
1
4
2
U17
From U14
Custom IC
BH2227
U4
1
PFMOTCU
12
AO1
DI
11 AO2 2
CLK
AO3 5
10
CSB
Low: Turns on Q4 to supply
power to the PF motor.
R105
Q5
DTC114EM
U18
Motor Driver
7
VSA
12
VSB
PFMA 6
INA
PFMA 5
INA
PFMB
17
INB
16
PFMB
INB
R106
3
REFA
14
REFB
C71
R107
SLA7033MPR
2-32
"(6) PF motor temperature
+24V
R104
Q4
XP132A11A1
PFMTCOM
8
OUT A
C69
1
OUT A
18
OUT B
C70
11
OUT B
[Main PCB]
J4
5
2
4 PF Motor
1
M
6
3