Reset Circuit - Casio 120CR Service Manual

A
B
A
Power ON 9.65 VAC 10.52V
Plug out 0
Voltage level is measured at the following condition.
1. Plug the power cord in AC outlet.
2. Mode switch position : REG, display 0.00
3. Put in the memory protection batteries.
4. Plug out : Plug out the power cord , the memory protection batteries in.

5-2. Reset circuit

RESET
Pin No.17
C N 8
A C IN
AC I N
1
7
G N D
H OT
5
1
6 1 0
T 1
C 1
B - 2
C 3
C 2 B -3
C -2
4 1
V F 2
C - 3
D - 3
F - 1
F - 2
C1 7
C 1 6
C28
E266-1
A C29
B-15
B C D
5.76V 10.45V
0 0 0
VDD
CPU does not work properly when the VDD is unstable.
The reset IC,S-80728AN, is used to know if the VDD is
S-80728AN
stable or not. When the VDD voltage becomes 2.8V or
more, the output of the reset IC becomes "H" level.
GND
— 9 —
D
ZD1
R2
B E
C10
R3
Q1
CN1
B-1
1 2
ZD2
Q2
C11
Q3
E B
C7
D6
E B
R4
R7
C5
D5 E B
Q4
C4
ZD4
D7
R 5
VN
T 2
R10
20 CN 3
C13
B-4 VF1
1
D-2
DISP1
Q5
E B
BZ1
C19
VDD
C- 3 Q6
X1
E
R13 B
R15
µPD 78 043 AGF
VP
C-11
X2
ZD5
R17
GND
B-10
C-21
C-22
C-15
C-23
C-16
C-17
E B
Q7
C-18
B-14
C-19
A-3 L2
C-20
A-4
IC4
LBI268
A-1
C31
A-2
L1
C30
E F
0.78V 0.12V Pulse
0 4.13V
C
G
I
H
GND
E
F
G H I
5.07V -23.9V
0 4.30V 0