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[b] Reset circuit
This circuit generates reset signals for the CPU and the external G/A, and is composed of IC6 and its peripheral circuits.
IC6 is provided with the reset function activated when the power is turned on and when the power falls below +5V.
The reset state is maintained until a certain time passes from when the power voltage reaches about 4.3V after supplying the power. The reset
maintaining time depends on the capacity of C9.
This circuit is also provided with the watch-dog timer function.
The watch-dog timer is built in the G/A (IC7) and is operated when RES2 turns HIGH. It monitors hung-up or other abnormalities of the CPU. RES2
is reset for the watch-dog timer in the G/A, and is separated from the CPU and RES1 of the G/A by D2. Therefore, the CPU reset and the G/A RES1
do not turn HIGH prior to RES2.
For monitoring, data (initial values) are written from the CPU to the G/A once for every 5ms. (Resetting to the initial values every 5ms.) The data are
counted down inside the G/A. Since the values are reset to the initial values every 5ms, the count normally does not fall to zero. If, however, a
hung-up of the CPU occurs, the data are not reset to the initial values, and the counter becomes zero. At that time, resetting is performed from the
G/A to the CPU and the G/A (RES1), and retry is performed until the CPU is resumed.
To main body via
interface cable
[c] Paper feed motor (DFM) drive circuit
This circuit controls the paper feed motor rotation and stop and the rotating direction. It is composed of the G/A (IC7) and the exclusive hybrid IC
(IC10), etc.
The motor rotation, stop, and rotating direction are controlled by the combination of binary logics inputted to the G/A through the data bus from the
CPU.
This provides control signals to the G/A 65 ∼ 68 pins.
The G/A 65 pin and 66 pin are for the PWM output for speed control. (Normal rotation, 65 pin; reverse rotation, 66 pin)
These signals are inputted to IC10.
IC 10 is a hybrid IC including 4 power MOSFET's, and drives the motor by taking the G/A output 65 ∼ 68 pins.
The motor operates as follows by the combination of 25 ∼ 28 pins.
—
65
Before start
0
CCW
0
CW
PWM
Brake
0
In the brake mode, the both terminals of the motor are shorted, generating a great braking torque to stop the motor.
G/A
(IC7)
67
MIH1
65
MIL1
68
MIH2
66
MIL2
72
CHGCLK
+5V
R61
4.7K
DF3-6P-2DSA
R52
RESET
CN9-6
4.7K
C43
0.1µ F
C4
1000PF
66
67
68
0
0
0
PWM
1
0
0
0
1
0
1
1
IC10
4
INA
OUT1-1
2
INB
OUT1-2
6
INC
OUT2-1
3
IND
OUT2-2
1
CLK
+5V
13
VCC2
VZ
VCC1-1
16
SG
VCC1-2
C72
0.1µ F
STK681-050
To power control circuit
Paper feed motor drive circuit
+5V
R58
4.7K
D6
Q5
2SC2712
DSA010
R30
10K
+5V
+5V
R9
IC6
7
IC5.3
10K
D2
VCC
6
5
6
C
OUT
GND
SB02-030
HD74LS06FP
C9
4
M51953BFP
0.33µ F
Reset circuit
10
DF1B-9P-2^5DSA
72µ H
L2
11
DFW1 CN5-1
SK-BMS-5H
6
L1
72µ H
7
DFW2 CN5-2
SK-BMS-5H
2
FD+24V
9
C34
8
1µ F
C68
0.1µ F
PGND
10 – 8
CPU
TP18
(IC11)
7
*RESET
C44
0.1µ F
G/A
(IC7)
37
RES1
C42
+5V
0.1µ F
TP23
R9
10K
5
38
WDT
39
RES2
Paper feed
DFM
motor
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