Carrier Leak Adjustment; Record Current Adjusment - Sony AV-3600 Service Manual

5-2.
CARRIER LEAK ADJUSTMENT
The
fm
signal
waveform must be symmetrical
throughout the
rf
system,
from
the
modulator
to the
demodulator or
carrier
energy
will
appear
in
the
picture as a
herringbone pattern.
Test Point:
Adjust
for:
Adjustment/
Board:
Monitor
screen
Minimum
carrier
leak
in
the picture.
R305/V1
(Limiter Carrier
Balance)
R326/V1
(Freq.
Doubler
Carrier
Balance)
R148/V2
(Modulator
Carrier Bal-
ance)
C122/V2
(Modulator
Carrier Bal-
ance)
Signal
Source:
Camera
signal or telecast signal
Equipment
Required:
Procedure:
(1)
TV
monitor
(2)
SONY
AV-Series camera
1
.
Check
carrier
frequency and
maximum
deviation.
See Sec.
5-1.
Note:
Because the procedure
in
Sec.
5-1
is
lengthy
and somewhat complicated,
it
may
be checked
and,
if
necessary, read-
justed after Sec. 5-2.
If
the procedure
in this
section
does not
yield correct
results,
however,
carrier
frequency and
maximum
deviation
must be
set (Sec.
5-1).
2.
Set
up
the E-to-E
mode
using
a
camera
or telecast
signal.
3.
Adjust
R305
(Limiter Carrier
Balance)*
and
R326
(Freq.
Doubler
Carrier
Balance)** for
minimum
carrier
leak (herringbone).
Repeat both
adjustments.
4.
Adjust
R148 (Modulator
Carrier
Balance) and
CI 22 (Modulator
Carrier
Balance) for
minimum
carrier leak.
Repeat both
adjustments, t
5
.
Repeat Steps
3
and
4.
6.
Make
a recording.
7.
Play
back the tape
and
observe the picture.
If
carrier
leak
is still
visible,
trim
up R305
and
R326
to
minimize
carrier
leak
in
the
playback
picture.
Note: *This
adjusts the operating
point of
Q302
so
that the
limiter stages
produce
symmetrical output waveforms.
** This
is
set
to obtain a
uniform-amplitude
detected
(frequency doubled)
fm
signal.
t
These components adjust the operating
point and the
RC
time constant of the
multivibrator (modulator)
so
that
it
produces
a
symmetrical output wave-
form.
5-3.
RECORD CURRENT ADJUSTMENT
The
following adjustment
sets
the
level
of
signal
applied
to
video heads
for recording.
Test Point/
Board:
Adjust
for:
TP-203/V2
(Rec. Current,
Ch
A)
TP-204/V2
(Rec. Current,
Ch
B)
1
V
(p-p)
rf
output
at
TP-203 (Ch
A) and
an equalized
rf
output
at
TP-204 (Ch
B).
1.0
Vp-p
(a)
Rf
output
at
TP-203
(a)
1.0
Vp-p
+m
(b)
Rf
output
at
TP-204
(b)
Fig. 5-3.
Record
current adjustment
5-4