Casio CZ-1 Service Manual And Spare Parts List page 96

11-6. After
Touch Control
Circuit
VDD
Kay
10KB
IK
'////////J
X
s
I
§
POS
s
POO
RO
AN2
WR
PF7
V
PFS
SN74LS174N-1
Tp
VCA
MJM466800-1
(Control voltogt
of ampiifiart
Invert
or
Aftar touch sansor
'L3139
(EACH
OICODiR/DSMULTIPLtXiRI
FUNCTION TABLE
li
°
2
1G
1A
IB
2G
2A
1Y2
2Y0
5r
AFTER TOUCH PARAMETER
IS
8
I
Noprastura
3.8V
2.0V
GNO
VC
output
h—
PrasturaMaa.
GNO
GNO
GNO
LS174
FUNCTION TABLE
(EACH FLIP-FLOPI
INPUTS
OUTPUTS
ENABLE SELECT
B
A YO Y1
Y2 Y3
X X
L L
L
H
H
L
H H
XZXrx xxrxx
zr
z
Z
Z
rzzzz
INPUTS
OUTPUTS
CLEAR CLOCK Q at
L
XX
H
t
H
H
t
L
H
L
X
L
H
H
L
L
H
Q« Go
H»highlaval. L*lowlaval.
X-irrtlnont
H«hioh
iaval
Ittntfy natal
L • low
lava! (staady itatal
X«kralavant
t "transition
from low
to
nig*
laval
Q# -tha
laval
of
O
bafora tna indicated steady *stata
input conditions
wara
establitned.
t
-
'176. LSI
75.
and
SI 75 only
(1)
Whtn
tht after
touch
sensor
is
pressed herder,
its
resistance
becomes lower dropping the voltage
level
of terminal
AN2.
(2)
Main
CPU
convenes analog
signal
into
digital
data
in
the
internal
AOC
(Analog to
Digital
Converter), then
output the data to
DAC
(Digital
to
Analog Converter) block.
(3)
These data
are
converted to analog signal
by
DAC
block.
(4)
The
output voltage
VC
is
input to
VCA
(M5241
L)
on
PCB AS1M,
to
vary the amplitude of the
VCA.
Note: Construction of after
touch
sensor.
I
nttr
-connect or
After touch sensor
is
a sheet of
silicon
rubber
in
which
carbon
particles are inlaid.
While no
force
is
applied, the resistance
between
the
both
sides
is
infinity.
However,
when
it is
pressed
hard,
the density of the carbon
becomes
high causing
i
its
resistance to
be as small as 10
-
30 ohms.
1
The
silicon
rubber
is
put between two
thin metal
plates.
.38-