Service manual
ER-A242U HARDWARE DESCRIPTION
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3. CLOCK GENERATOR
1) CPU
Two oscillators are connected to the CPU.
The basic clock X2 is supplied from a 12MHz oscillator.
If the CPU was not operating properly, the signal does not appear on
this line in most cases.
The sub-clock X1 generates 32.768KHz which is primarily used to
update the internal RTC (real time clock).
During the standby mode, it keeps oscillating to update the clock and
monitoring the power recovery.
4. RESET CIRCUIT
(1) When the mode switch is placed in the “SRV” position, the reset sig-
nal is sent to the CPU to reset the hardware.
(2) When VDD t 2.8V, a reset signal is outputted from the reset IC.
(S-80928ANMP)
5. P-OFF CIRCUIT
53 A17 A17 Out Address bus :17
54 A16 A16 Out Address bus :16
55 A15 A15 Out Address bus :15
56 A14 A14 Out Address bus :14
57 A13 A13 Out Address bus :13
58 A12 A12 Out Address bus :12
59 A11 A11 Out Address bus :11
60 A10 A10 Out Address bus :10
61 A9 A9 Out Address bus :9
62 VCC VDD In VDD
63 A8 A8 Out Address bus :8
64 VSS VSS In VSS
65 A7 A7 Out Address bus :7
66 A6 A6 Out Address bus :6
67 A5 A5 Out Address bus :5
68 A4 A4 Out Address bus :4
69 A3 A3 Out Address bus :3
70 A2 A2 Out Address bus :2
71 A1 A1 Out Address bus :1
72 A0 A0 Out Address bus :0
73 P17 ENA2 Out Paper feed motor :ENA2
74 P16 ENA1 Out Paper feed motor :ENA1
75 P15 IN2 Out Paper feed motor :IN2
76 P14 IN1 Out Paper feed motor :IN1
77 P13 P13 Out Key/Display
78 P12 P12 Out Key/Display
79 P11 P11 Out Key/Display
80 P10 P10 Out Key/Display
81 D7 D7 InOut Data bus :7
82 D6 D6 InOut Data bus :6
83 D5 D5 InOut Data bus :5
84 D4 D4 InOut Data bus :4
85 D3 D3 InOut Data bus :3
86 D2 D2 InOut Data bus :2
87 D1 D1 InOut Data bus :1
88 D0 D0 InOut Data bus :0
89 AN7 STB1 Out Printer head strobe
90 AN6 LATCH Out Printer data latch
91 AN5 P105 Out Printer head voltage ON
92 AN4 P104 Out CG ROM Bank
93 AN3 P103 In VBAT
94 AN2 Vref In NU Vret
95 AN1 P101 In Printer head voltage check
96 AVSS VSS In VSS
97 AN0 TH In
Print head temperature check
98 VREF VDD In VDD
99 AVCC VDD In VDD
100 SIN4 P97 In Key IN
Pin
No.
SYMBOL
SIGNAL
NAME
In/
Out
Function
11
10
27P
C
CPU
XIN
X1
32.768KHz
13
18P
C
15
XOUT
XCOUT
XCIN
R
330
12MHz
CPU
R
/RESET
C
MODE SWITCH
SRV' position
VDD
11
R
C
VDD
IC
S-80928ANMP
R
VCC VLED
R15
2.7K
R16
9.1KG
R20
2.7K
/POFF
C15
0.1uF
5
6
7
8
4
IC4B
BA10393
P-OFF
ZD4
MTZJ5.1B
R19
56K
3
2
1
8
4
IC4A
BA10393
R17
0
R18
3.9K
C14
1uF/50V