Sharp SF-A57 Service Manual page 35

B. Solenoid drive circuit
[a] Paper feed solenoid (DFSOL), reverse solenoid (DRSOL) drive circuit (DRSOL --- SF-A57 only)
This circuit drives the weight plate which presses the bundle of originals on the tray, the paper feed solenoid which drives the paper feed section
shutter, and the reverse solenoid which drives the reverse guide to lead an original to the reverse path when reversing. The basic composition is the
same. The drive signal (ON at HIGH) from the gate array is inputted to the gate of FET (Q14, Q15).
The ON duty of the drive signal can be varied from 0 to 100% (255 steps). The frequency, however, is 20kHz.
G/A
(IC7)
15
PWM2
14
PWM1
C. Fan motor drive circuit
The fan motor is provided with the lock detection function to cool the power source and the control PWB.
When a HIGH level is outputted from the gate array (IC7-20pin), the transistor (Q16) conducts to drive the fan motor. At that time, the lock detection
signal is outputted from the fan motor. In normal operations, a LOW level is outputted and transmitted to the gate array (IC7-58pin).
In case of abnormal operation, a HIGH level is outputted.
G/A
(IC7)
20
PWM7
58
P5
SS14
TP28
Q14
2SK1726
R88
1.0K
PGND
SS14
TP36
Q15
2SK1282-Z
R82
1.0K
PGND
Solenoid drive circuit
TP48
C
R88
B
1.0K
Q16 E
RN1427
PGND
R16
10K
CRG10G103J
CRG10G103J
C27
GRM40B103K50PT
0.010µ
GND
Fan motor drive circuit
+24V
173981-7
D8
+24V CN8-4
DRSOL CN8-5
FD+24V
DF1B-9P-2^5DSA
D7
+24V CN5-4
DFSOL CN5-3
DC+24V
D10
SIG
173981-8
+24V CN8-7
A K
DRSOL CN8-8
+5V
R15
4.7K
R17
CRG10G472J
10K 173981-8
FANARM
CN8-6
– 34 –
Reverse
DRSOL
solenoid
Paper feed
DFSOL
solenoid
CFM
Fan motor