Read Sharp ER-A310 (serv.man2) Service Manual online
7. Keyboard circuit
The keyboard performs key scanning with the eight strobe signals
ST1-ST8, and returns the nine return signal KR1-KR9 to the CPU.
ST1-ST8, and returns the nine return signal KR1-KR9 to the CPU.
The mode switch performs scanning with the eight strobe signals
ST1-ST8, and returns the return signal KR10 to the CPU. When the
mode switch is at SRV position, the reset signal /RESET is outputted.
ST1-ST8, and returns the return signal KR10 to the CPU. When the
mode switch is at SRV position, the reset signal /RESET is outputted.
The one hole cashier switch performs scanning with four strobe sig-
nals ST1
nals ST1
∼
ST4, and returns the return signal KR11 to the CPU.
8. Display circuit
The 7-segment LED is used in the display. The operator display uses
10 digit signals, and the pop-up display uses 7 digit signals.
10 digit signals, and the pop-up display uses 7 digit signals.
9. Power supply circuit
10. Battery voltage monitor circuit
The battery voltage signal is inputted to the CPU P10 and the com-
parison reference voltage VCC (+5V) is inputted to the CPU VREF to
monitor the battery voltage. When the input to P10 falls below
7/10VCC=+3.5V, the low battery display is made.
parison reference voltage VCC (+5V) is inputted to the CPU VREF to
monitor the battery voltage. When the input to P10 falls below
7/10VCC=+3.5V, the low battery display is made.
IC2
CPU
ST8
ST6
ST4
ST2
ST1
ST7
ST5
ST3
KEY MATRIX
KR1
KR2
KR3
KR4
KR6
KR7
KR8
KR5
KR9
RA2
56K X 8
R102
56 K
D 9
D11
D13
D15
D16
D10
D12
D14
MODE SWITCH
ST1~ST8
/R ESET
KR10
C11
M104
R40
56 K
56 K
D17
1SS133
ST 1 ~ ST 4
KR 1 1
R5 2 56K
D 1 8~D 2 1
ONE HOLE
CASHIER KEY
DIG1'
DIG9'
DIG10'
DIG2'
A,B,C,D,E,F,G,DP
DP'
G'
F'
E'
D' C'
B'
A'
A',B',C',D',E',F',G',DP'
A',B',C',D',E',F',G',DP'
DIG1-DIG10
FND5
FND1
FND4,3,2
IC2
CPU
+6V
POP UP
DISPLAY
DIG1'-7'
Operator Display
DP~A
REGURATOR
CIRCUIT
POWER
TRNSFORMER
F1
T1AL/250V
P-OFF
CIRCUIT
REGURATOR
CIRCUIT
BATTERY
CITCUIT
VP:+24V(ER-A310)
+18V(ER-A330)
+6v
VCC:+5V
PE
VDD:+5V
: PRINTER, DRAWER
: DISPLAY
: CPU,RAM
VB
IC2
CPU
AVREF
P10
VB:+1.5V X 3=+4.5V
VCC:+5V
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