Akai GX-M10

Vil.
IPSS
CIRCUITRY
OPERATION
EXPLANATION
¥ © CLEAR PROGRAM © \
LINE OUT
De
(LEFT)
BLANKING
DISPLAY
COMPARATOR
REFERENCE
VOLTAGE
LINE OUT
2 (RIGHT)
he
LINE AMP
-
TAPE COUNTER
& (000)
ONE SHOT PULSE :
GENERATOR
STOP
|
peu
ON
OorF
|
IPSS
OMEMORY
ae
OOFF
AUTO SYSTEM
1.
IPSS
(Instant
Program
Searching
System)
is
the
pro-
graming
in
advance
of
the
song
or
songs
(up
to
9
from
the
present
position
on
the
tape)
you
want
to
listen
to.
When
the
FF
or
RWD
and
PLAY
keys
are
depressed
simultaneously,
the
no
signal
portion
between
songs
is
detected
by
the
REC/PB
head
and
the
number
of
these
is
counted
down
according
to
the
programmed
number
of
songs.
As
it
goes
from
1
to
0,
the
FF
or
RWD
key
is
released
and
it
enters
the
Play
mode.
2.
CIRCUITRY
DETECTING
THE
NO
SIGNAL
PORTION
(Refer
to
Figs.
6,
7,
&
8)
When
the
FF
or
RWD
and
PLAY
keys
are
depressed
simultaneously,
the
REC/PB
contacts
the
tape
and
the
signal
on
the
tape
is
picked
up
by
REC/PB
head.
The
head
is
about
1.7
mm
lower
than
it
would
be
in
the
playback
mode.
The
picked
up
signal
is
added
to
input
IC1-1
@
in
the
Limiter
Amp.,
it
is
amplified,
detected
by
D2
and
added
as
TR1’s
base
bias.
TR1
is
ON
and
IC1-2
©
is
practically
earth
potential.
The
standard
voltage
of
the
Comparator
(IC1-2)
is
1/2
Vcc
(about
6V)
so
the
output
@
becomes
Vcc
(about
12V).
When
a
no
signal
portion
is
reached,
base
bias
is
not’
added
to
TRI
and
it is
turned
OFF.
C3
charges
and
IC1-2
@
becomes
Low
Level
at
the
point
that
|, [i
F.F./RWD KEYS REC KEY REC MUTE BUTTON
Fig.5
IPSS/MEMORY
SYSTEMS
BLOCK
DIAGRAM.
NOTE
1. SWITCHS ENCLOSED BY [___] ARE MANUAL.
2. & 1S A SWITCH CIRCUIT.
LEFT AND RIGHT ARE CONNECTED ONLY
WHEN A COMMAND IS INPUT 4.
IC1-2 ©’s potential exceeds the standard voltage
(1/2 Vcc) in the comparator. As a result, charging
current flows into C5 and a trigger pulse is generated
at the cathode side of D14. IC2 counts down by this
pulse’s falling portion.
C2 and RS are to compensate for the high frequency
level drop caused by the head not touching the tape
perfectly.
When there is noise in the portion between songs
on the tape, there is more than one trigger pulse
generated in the portion making miscounting a
probability. C5’s charged and discharged electricity
are used to prevent this occuring.
C5 is charged through D3 and R56 while IC1-2 @ is
at
Low
Level
(no
signal
portion
between
the
songs
on
the tape) and both terminal’s voltage difference is
almost Vcc (+12V). When the no signal portion is
over IC1-2 @ becomes High Level and because it is
piled on to the potential charged to C5, D14’s
cathode side’s potential becomes higher than +B’s
(+12V) potential. Then C5 will discharge through
R14 until both terminal’s potentials are equal. Until
C5 discharged down to a certain level even if
IC1-2 @ becomes Low Level, only a small trigger
pulse is created in the D14 cathode side and does not
reach
the
IC2’s
DOWN
COUNT
operation
level.
Therefore the programme counter does not count.
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SERGE
9