Kenwood TM-221A Service Manual page 7

comM1
COMS
@ Display circuit
Located in the LCD assembly (Fig. 8), the display
circuit consists of the LCD driver, its peripheral circuits,
and the LCD. The LCD is driven with a 50% duty cycle
BUSY
Me
Pant
a
Og0gn000006
CALL
rm
2)
33
34
35
36
37
38
39
40
"1
42
43
44
45
46
47
48
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ap 8S
SCAN ce) Sa
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LC7582
58 59
Po s7|
TM-221A/E/ES
CIRCUIT DESCRIPTION
according to serial data sent from pins P71 to P73 of the
microprocessor to the LCD driver. Fig. 9 shows the
common output and segment output signals of the LCD
driver.
8 ow
5x8
«ew @
tek Bs
nok oo
Vico
ra Ch bruce
GND
VicD
ee Crier ei
GND
$1~$52 —
Only the COM1
side is ON. : GND
COM1 and COM2 vie
side is ON. GND
Only the COM2
side is ON.
VLCD
VLCD
<>
COM1 and COM2
side are OFF.
1
fosc/si2 SEC
Fig. 9 LCD driver common and segment
100
[|
[|
oO 2 m °
680P
2.7K
output signals
047
Fig. 8 LCD ass'y (B38-0303-05)