Sharp SF-2220, Service Manual

Page: 162 / 163

Pin
No.
Used
Port
Sig. Name I/O Active Note
42 A6 Address signal
43 A5 Address signal
44 A4 Address signal
45 A3 Address signal
46 A2 Address signal
47 A1 Address signal
48 A0 Address signal
49 D0 Data signal
50 D1 Data signal
51 D2 Data signal
52 D3 Data signal
53 D4 Data signal
54 D5 Data signal
55 D6 Data signal
56 D7 Data signal
57 P4-0 DPFC O H Take-up roller clutch signal
58 P4-1 DRRC O H Transport roller clutch signal
59 P4-2 PS O — Not Used
60 /RD ROM READ pin
61 /WR Stepping motor data
WRITE pin
62 /AS Address strobe pin
(H-lev. fixed)
63 /CLK System clock pin
(H-lev. fixed)
64 /WAIT Wait pin (H-lev. fixed)
(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 Drive signal ACT
H’FF80 D0 PAM1 A H
H’FF80 D1 PAM1/A H
H’FF80 D2 PAM1 B H
H’FF80 D3 PAM1/B H
H’FF80 D4 PAM2 A H
H’FF80 D5 PAM2/A H
H’FF80 D6 PAM2 B H
H’FF80 D7 PAM2/B H
*
The power source is driven by VB.
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.
A
A
B
B
Stepping motor time chart
B B +24V
Phase B Phase B
A
A
+24V
Phase A
Phase A
12 – 20
MC-Service