Truth
table
of
IC
1
Pins@and@in
accordance with tension
ann
positions
@Pin
L
H
L
L
L
ICI
31
I
____
.J
(19)
Pin
L
L
L
H
L
Function
mode
lndlcotor
4-2-3
FUNCTION
MODE
INDICATOR CIRCUIT
AND
COUNTER CIRCUIT
• Function Mode Indicator Circuit
The function mode indicator lighting
is
also
controlled by the operation timing
of
the
control signal from the microcomputer.
Here
we
will explain about the situation in Fig.
6-37. (FWD PLAY/PAUSE)
as
one example.
Hereinafter
FWD
PLAY
is
just written
as
PLAY.
Under PLAY/PAUSE,
PAUSE
of
the function
mode indicator
is
always
is
lit and PLAY
is
flashing. Firstly, refer to the vertical raw
of
the
function mode indicators
of
00
-03
in
Fig. 6-37.
You will note that PAUSE IND has
"H"
level,
PLAY IND has
"L/H"
flashing and others have
"L"
level.
The signals
of
(00
-
03)
and
IC
@ enter
IC3
and
IC4
and TR83 in Fig. 6-36. In this way the
digits
of
the function mode ind. and PLAY/
PAUSE
IND.
are
inputted.
When
these two
digits
are
synchronized, the indicator
is
lit.
Lock
.j,
Play key
is
pressed
Middle
.j,
Shut-off
Lock
Fig. 6-35
COUNTER
PCB
TI009C2550
• Counter Indicator Circuit
Fig. 6-36
The counter indicators
are
also
lit by
the
pulse
from the microcomputer, and
it
is
not that
all
the indicators are always lit.
Because
of
the afterimage, it appears to our
eyes that
all
the digits
are
lit despite the fact
that they are lit in sequence as
shown in Fig.
6-38. This system
is
called dynamic lighting
system.
Fig. 6-37 shows the timing chart. By ['leans
of
the waveforms
of
IC@-@
coming
from
the
microcomputer, the lighting position
or
LED
of
each digit
is
moved in sequence.
T~e
the
example
of
the first digit.
The first digit can only
be
lit when
tl>.e
wave-
form
of
IC
@
is
"H"
level.
Dependii1B
on the
condition
of
00
-
06
at the time
of
'H"
level,
each segment
is
lit and the figure is in.dicated.
Since the segments
of
the LED in'1icators
are cathode common, each segment
is[jt
when
00
-
06
are at
"H"
level.
If
we
see He condi-
----------------SERVICE
MANUAL
GX-747dbx----------------
22
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