Sharp VC-90ET

” VC-9OET
m
ADJUSTMENT
OF
Y/C
CIRCUIT
Adjustment
of
EE
level
PMode
|
Recording
—SSS—=*S
(stair-case
waveform)
Adjusting point | R218 (EE level control)
2.0 + 0.1Vp-p (not terminated)
. Set the unit in record mode.
2.
Feed
the
colour
bar
signal
to
the
video
input
terminal.
Observe
the
voltage
the
pin
9
of
1C201
on
the
oscilloscope
screen,
adjust
R218
(EE
level
control)
to
obtain
the
value
indicated
in
Figure
2-7.
a
Adjustment of white clip
[Mode
[Rewraing
Standard
colour
bar
(stair-case
waveform)
Adjusting
point
|
R223
(white
clip
control)
1. Place the unit to the redord mode.
2.
Feed
the
colour
bar
signal
to
the
video
input
terminal.
3.
Turn
R227
clockwise
to
maximum
position.
4. Observing the output at TP201, adjust R223
(white
clip
control)
so
that
the
white
peak
overshoot be 80 + 4%.
5. Make sure that the dark peak overshoot is
50+ 10%.
=
2.0Vp-p
WHITE
CLIP
80%
100%
Soi Figure 2-8 20psec/div
Adjustment of FM3.8MHz and 4.8MHz
Measuring | Frequency ‘
Recording Self-recording /
playback
Input
signal
|
External
input
ep
colour
;
;
ar
(stair-case
inesiana) waveform)
Test
point
TP205
(Signal)
|Video
output
TP202 (Ground) | terminal
Adjusting
R227
(FM
R228
(Deviation
point
carrier
control)
|
control)
Specification
|
3.8
1.0
+
0.04
Vp-p
MHz + 50KHz
Note.1:
Carry
out
this
adjustment
only
when
!C201
has
been
replaced
or
when
the
carrier
setting(3.8MHz)
or
the
deviation(4.8MHz)
is
found
apparently
out
of
specification.
Make
this
adjustment
after
the
EE
level
has
been
completely adjusted.
Note.2:
The
video
output
terminal
should
be
terminated
with a 75-ohm impedance.
1.
First
make
sure
that
the
EE
video
signal
level
is
at
the
specified
level.
2.
Plase
the
unit
in
the
record
mode
and
get
it
ready
for
external
input.
Note:
Do
not
connect
anything
to
the
external
input
terminal.
3.
Hook
up
the
frequency
counter
to
TP205
and
TP202.
Adjust
R227(FM
carrier
control)
so
that
the
counter
reading
be
3.8MHz.
Note:
Make sure the white clip control is not now
applied to the waveform.
4. Feed the colour bar signal and make sei4-
recording and playback.