4-2-1
FUNCTION
MODE
SELECTOR CIRCUIT
Selection
of
the function mode
is
controlled
by
the pulse timing using a microcomputer.
For easier understanding, one input terminal
@ will be explained
as
an
example. The
terminal
@ receives four
~als,
i.
e., the
strobe signals
from@
,@
6
@
and~.
Each pulse
signal
from @ , @ ,
Q§)
and
@ has a different timing. Assuming that the
signals from these terminals are 1000, 0100,
0010 and 0001,
signal
1000
of
Terminal
@will
pass D84, and through the collector
of
TR85,
it
will enter the emitter
of
TR60.
If
FWD
(SW3) button
is
pressed, the base
of
TR60 is earthed through R202, TR60
is
energized, and Signal 1000
will
be outputted
into Terminal
@
of
ICl through D60.
r-----------7
If
any input
is
made into
·@
, it
is
processed
within the microcomputer depending on the
signal and the signal
is
outputted from the
respective terminal.
If
1000 is inputted into
@ , it
is
judged
as
FWD
and the related
signal
is
inputted to the output terminal.
(See
Fig. 6-27). Similarly,
Signal
O 100
from@
passes the emitter and collector
of
TR86 and
enters the Counter
P.C
Board.
When
the pro-
gram
SW
(SW6)
is
pressed, Signal 0100
is
inputted into
1c1@.
Signal 001 O
from@pas-
ses
the collector/emitter
of
TR87, and through
D66 and the reverse selector
SW
L__
, it
is
inputted into ICl
@.
Signal 0001 from @
passes SRI and
SW906
and
is
inputted into
@.
I IC-I
~
1,
~
3
1
5
_6
__
F_wo
__
6_P_RO_G_RAM
__
6
_C-~
0
SW906
KEY
SW
REVERSE
:
~
PHo 26
SELECTOR
I
~
I
I
~
I
I
~
L
_________
....1
Fig.
6-27
Input
to
®
Judgement and Output by Microcomputer
1000
Output H to
Terminals(}
2)
,QA),@
and
(25)
of
ICl
(FWD
output order).
0100
Act
as
clear/program
SW
only when
MEMORY
AUTO
REV
SW
is
ON.
0010
Act once
as
a
reverse
equipment.
(SW
906
is
ON
and tension arm is locked)
0001
When
FWD,
REV, FF or
RWD
key
is
pressed, process the other
signals
after making
Terminal
(is)
H.
Fig. 6-29 shows the truth table when the function switches
are
pressed.
Function
SW
Term~
FF
FWD
STOP
12
H
H
13
L L
14
H
H
15
H L
16
L L
17
L
H
24
H L
25
H
H
Note: H of
Terminal@:
_jl__
H of other Terminals:
_r-
H
L
L
H
L
L
L
L
REV
REW
PAUSE
H H
H
L
L L
H
H L
L H
L
H
L
L
H
L
H
L H
L
H L
L
Fig.
6-28
REC
REC
MUTE
REC PAUSE
L
H a
H H a
H
L
L
L
L
L
L L
L
H H
ll
L L L
H H L
Fi~-
6-29
---------------SERVICE
MANUAL
GX-747dbx---------------
19
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