Sharp SF-2220 Service Manual page 162

Pin Used
Sig. Name I/O Active
No. Port
42 A6
43 A5
44 A4
45 A3
46 A2
47 A1
48 A0
49 D0
50 D1
51 D2
52 D3
53 D4
54 D5
55 D6
56 D7
57 P4-0 DPFC O
58 P4-1 DRRC O
59 P4-2 PS O
60 /RD
61 /WR
62 /AS
63 /CLK
64 /WAIT
(3) Stepping motor (PAM1, PAM2) drive circuit
The write data is latched by the HC374 at the writing timing of exter-
nal address. When the stepping motor output signal (P6-0) becomes
LOW, the excitement signal of the stepping motor is sent to the
transistor array IC of IC2, 3, driving PAM1 and PAM2.
Write address Data bus
H'FF80 D0
H'FF80 D1
H'FF80 D2
H'FF80 D3
H'FF80 D4
H'FF80 D5
H'FF80 D6
H'FF80 D7
* The power source is driven by VB.
Note
Address signal
Address signal
Address signal
Address signal
Address signal
Address signal
Address signal
Data signal
Data signal
Data signal
Data signal
Data signal
Data signal
Data signal
Data signal
H Take-up roller clutch signal
H Transport roller clutch signal
— Not Used
ROM READ pin
Stepping motor data
WRITE pin
Address strobe pin
(H-lev. fixed)
System clock pin
(H-lev. fixed)
Wait pin (H-lev. fixed)
Drive signal ACT
PAM1 A H
PAM1/A H
PAM1 B H
PAM1/B H
PAM2 A H
PAM2/A H
PAM2 B H
PAM2/B H
MC-Service
Stepping motor time chart
A
B
A
B
A
Phase A
+24V
Phase A
A
A: Stepping motor phase A coil drive circuit
B: Stepping motor phase B coil drive circuit
A: Stepping motor phase A coil drive circuit
B: Stepping motor phase B coil drive circuit
(4) ADU motor (DDM) drive circuit
The CPU supplies signals of two systems, which are process by the
hardware to drive DDM.
Drive and non-drive speed control is performed with DDM_PWM, and
normal/reverse rotation of the motor is performed with DDM_DIR.
When paper enters the ADU, DDM is driven with DDM_DIR at LOW,
Q3 ON, and Q1 OFF.
When paper enters the ADU, DDM is driven with DDM_DIR at LOW,
Q3 is turned ON and Q1 is turned OFF.
When DDM_PWM is HIGH, Q2 is turned OFF and Q4 is turned ON
by Q3.
In IC8, therefore, A-OFF, B-ON, D-OFF. The motor current flows
through VH → B → M → C → GND to drive the motor.
The motor rotation is controlled with the PWM control.
When paper is discharged from the ADU, DDM_DIR is HIGH, Q3 is
turned OFF and Q1 is turned ON.
When DDM_PWM is HIGH, Q4 is turned OFF and Q2 is turned ON
by Q1.
In IC8, therefore, A-ON, B-OFF, C-OFF, D-ON. The motor current
flows through VH → A → M → GND to drive the motor.
The motor rotation is controlled with the PWM control.
When the motor is not driven, DDM_PWM and DDM_DIR are LOW.
12 – 20
Phase B Phase B
B +24V B