Service manual

ER-A242U HARDWARE DESCRIPTION
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1) Keyboard
Scan signal: 10 /S0-9 signals
Return signal: 6 P92-97 signals
The keys are read by the key matrix following the above signals.
2) Mode switch
Scan signal: 8 /S0-7 signals
Return signal: 1 P90 signal
The positions are read by the above signals.
3) Paper feed key
Scan signal: 1 /S1 signal
Return signal: 1 P91 signal
The paper feed key is read by the above signals.
4) Head up sensor
Scan signal: 1 /S3 signal
Return signal: 1 P91 signal
The Head up sensor state is read by the above signals.
5) Paper end sensor
Scan signal: 1 /S4 signal
Return signal: 1 P91 signal
The paper end sensor state is read by the above signals.
6) RS232/CI signal detection
Scan signal: 1 /S9 signal
Return signal: 1 P91 signal
The RS232/CI signal is detected by the above signals.
7) Display
Scan signal: 10 /S0-9 signals
The above 10 scan signals are used as the following digit signals.
Digit signal:
Segment signal : Segment signals: a, b, c, d, e, f, g, and DP are output
by the IC:74HC374, using the data bus signal:D0-7
from the CPU as an input signal and the chip select
signal:/CS3 as a latch signal.
12. RS232 CIRCUIT
The signals from the CPU are converted by the HIN211 into the RS232 level to input and output them.
Scan
signal
/S0 /S1 /S2 /S3 /S4 /S5 /S6 /S7
Mode
switch
position
SRV PGM (OFF) TIME REG MGR X1/Z1 X2/Z2
Head up sensor Head up detected Head up not detected
P91 Low High
Receipt near end sensor End detected End not detected
P91 Low High
RS232 /CI signal /CI signal detected /CI signal not detected
P91 Low High
Scan signal /S0 /S1 /S2 /S3 /S4 /S5 /S6 /S7 /S8 /S9
Digit signal:
Front
G1’ G2’ G3’ G4’ G5’ G6’ G7’ G8’ G9’ G10
’
Digit signal:
Pop-up
G1’ G2’ G3’ G4’ G5’ G6’ G7’
CPU
HIN211
1
D-SUB 9pin connector
2
3
4
5
6
7
8
9
CD
RD
SD
ER
GND
DR
RS
CS
CI
R1IN
R2IN
T3OUT
T2OUT
R4IN
R5IN
T1OUT
R3IN
R1OUT
R2OUT
T3IN
R4OUT
T2IN
T1IN
R5OUT
R3OUT
P75
P66
P77
P67
P74
P64
P91
P76
CD
RD
SD
ER
DR
RS
CI
/S9 Q14
D16
IC14
CS