Read Sharp XE-A202 Service Manual online
XE-A202V
HARDWARE DESCRIPTION
– 9 –
The P-OFF signal detects two signals by two comparators and sent to
the CPU.
the CPU.
V0 (24V) signal: If the power voltage V0 (24V) falls bellow the specified
level, the P-OFF signal is driver to LOW by the com-
parator ICAA.
VLED signal:
If the LED/Logic power voltage VLED falls below the
specified level, the P-OFF signal is driven to LOW by
specified level, the P-OFF signal is driven to LOW by
the comparator IC4B.
6. MEMORY CIRCUIT
1) Address map
2) RAM control
7. PRINTER CONTROL CIRCUIT
1) Paper feed motor circuit
Stepping motor control
The 2-phase, bi-polar stepping motor is driven at a constant voltage by
LB1838M (made by SANYO).
1 step: 0.087mm
1 dot: 2 steps
CPU port
Drive step
2) Print circuit
Thermal head configuration
As shown in the equivalent circuit in the figure, thermal head consists of
heating elements and head drivers which drives and controls those
heating elements.
heating elements.
The serial print data input through the DATA IN (D1) is transferred to
the shift register synchronizing with the CLOCK (CP) and stored in the
latch register by the LATCH (LA) signal.
The head conduction signals (print commands 1 ~ 6) turn the gate on to
conduct the heating element corresponding to the print data.
conduct the heating element corresponding to the print data.
Segment latch address
00000h
00400h
05400h
06000h
08000h
40000h
28000h
C0000h
FFFFFh
CPU internal RAM
20kbytes
External S-RAM : 128kbytes
(128kbytes area)
CPU internal ROM
256kbytes
/CS2 area
08000h - 27FFFh
08000h - 27FFFh
/CS3 area
06000h - 07FFFh
06000h - 07FFFh
CPU
S-RAM
128K byte
IC
A0-A16
D0-7
A0-A16
A0-A16
D0-7
I/O0-7
/CS2
/CS2
/CS1
/RD
/RD
/WR
/WE
/WR
/OE
Power supply circuit
or
Dry battery
VDD
VCC
VDD
VCC
VCC
CS2
0.1M
11
10K
10K
150pF
10K
No.
CPU port
Signal used
76
P14
IN1
75
P15
IN2
74
P16
ENA1
73
P17
ENA2
Driver IC input
(CPU output)
Motor drive signal
STEP
IN1
IN2
ENA1
ENA2
A
(OUT1)
B
(OUT3)
/A
(OUT2)
/B
(OUT4)
1
L
L
H
H
H
H
L
L
2
H
L
H
H
L
H
H
L
3
H
H
H
H
L
L
H
H
4
L
H
H
H
H
L
L
H
CPU
IC13
VH
/A
A
B
/B
/B
VCC
LB1838M
MOTOR
10uF/50V
P14
P15
P16
P17
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