Sharp VC-90ET

VC-9OET
Adjustment
of
drop
out
level
Measuring
[Mode
|
Playback
PAD
Finputsignal——[————
TP6303, TP6306 (GND)
Adjusting
point
R6366
(drop
out
level
control)
Spedfication
[38201
1.
Put
the
set
in
playback
mode.
2.
Connect
an
VTVM
to
TP6303
and
TP6306,
and
adjust
R6366
(drop
out
level)
so
that
output
available
on
the
oscilloscope
is
3.8V
+
0.1V.
Checking
of
playback
switching
point
Measurin
.
rode
—__|
Playback
(PAL/NTSC)
Tape
used
Hi-Fi
alignment
tape
VROCBFFS
PAL
VROATFCS
NTSC
T7305, T6307
el
a
Longer than 100 psec.
1.
Connect
the
oscilloscope’s
CH1
to
TP6305
and
its
CH2
to
TP6307.
Connect
the
external
trigger
to
TP2
(Main
PWB).
2.
Play
back
the
standard
HiFi
tape
(VROCBFFS).
Externally
trigger
the
circuitry.
Observe
the
output
at
TP6305
and
TP6307
at
the
same
time
on
the
oscilloscope
screen.
3.
Make
sure
that
the
envelope
at
TP6305
is
longer
than
100psec.
ahead
of
the
leading
edge,
and
behind
the
trailing
edge,
of
the
output
at
TP6307.
Notes:
1.
Before
making
this
adjustment,
make
sure
that
the
video
playback
switching
point
has
been
accurately
adjusted.
Be
sure
to
make
this
adjustment
when
this
switching
point
has
been
adjusted.
If
the
measurement
is
out
of
specification,
readjust
the
playback
switching
point
to
the
6.5-0.5H
range.
2.
Make
this
adjustment
just
after
the
A/C
head
height
and
azimuth
have
been
adjusted.
It
is
acceptable
that
the
envelope
is
longer
than
100psec.
ahead
of
the
leading
edge
of
the
head
switching
pulse
signal
at
TP6307.
42
TP6307
1 < 1
Longer than 100psec
Figure 2-23.
Adjustment
of
Hi-Fi
playback
level
Measuring
instrument
-
VTIVM
Mode
——_|
Playback
(PAL/ NTSC)
Tape
used
Hi-Fi
alignment
tape
(VROCBFFS)
(PAL)
(VROATFCS)
(NTSC)
input signal
Test
point
Audio
line
output
terminal
(L,
R)
Adjusting
point
R6364
[R6382]
(playback
level
control)
.
Playback
the
Hi-Fi
alignment
tape.
2.
Connect
CH-1
of
an
VTVM
at
the
audio
line
output
terminal
(L),
CH-2
of
an
VTVM
at
the
audio
output
terminal
(R)
and
then
set
the
audio
output
select
to
Hi-Fi
and
stereo.
3.
Adjust
R6364
[R6382]
to
the
point
at
which
the
playback
level
is
—
8dBs
+
1dBs.
_
Adjustment of level meter
Measuring
instrument
Level
meter
puto
Test pin
aajstng pa
Specification
1.
Input
-8dBs,
1kHz
audio
oscillator
signal
to
the
audio
line
input
terminal.
2.
Set
the
audio
input
switch
to
external.
3.
Audio
output
switch
should
be
set
to
stereo
position.
4.
Adjust
R6351
[R6352]
so
that
the
level
meter
lights
as
for
as
the
0
dB
point.
5.
Then,
receive
a
monaural
signal,
and
adjust
R6352
so
that
the
input
levels
of
both
L-CH
and
R-CH
become
the
same.