30 Pg Pulse Phase Check; Servo-Reference Delay Mv (Rec) - Sony AV-3600 Service Manual

Interaction:
This
adjustment
may
interact
with those described
in Sections 6-5, 6-9,
and
6-11.
Whenever 30
PG
coil
A
is
adjusted, check
and,
if
necessary, readjust these
sections.
6-9.
30
PG PULSE PHASE CHECK
This
procedure
sets
up
the precise angular
dis-
placement between
the
two 30
PG
coils.
One
30
PG
coil
should be
exactly
180°
from
the other.
When
properly adjusted, correct interlace
is
achieved
in
the
playback
picture
and
vertical jitter
is
minimized. This
adjustment
follows
"30 PG
Pulse Position
Check"
in
Sec. 6-8.
CAUTION
Avoid adjustment
of the
30
PG
coil
unless
tests
indicate that the adjustment must be made.
Test Point/
Board:
TP-412/SV
(Shaped 30
PG
pulse out-
put)
Adjust
for:
Minimum
phase
difference
leading
edge
J
f
n
incorrect
overlap
^^^
trailing
edge
Fig. 6-9.
30
PG
Pulse
phase Check
Adjustment:
Signal Source:
Equipment
Required:
30
PG
Coil
B
Telecast Signal
(1)
Oscilloscope
(2)
TV
monitor
Procedure:
1
.
Set
up
the E-to-E
mode
using
a telecast signal.
2. Connect the scope to TP-412.
3.
Sync the scope
externally
from TP-406.
Set the
time base to
5
ms/cm.
4.
Turn
the
VARIABLE
control of the
scopes
time-base counterclockwise (from the CALIB-
RATED
to the
UNCALIBRATED)
until
two
pulses
can be
seen
at
the
same
time on
the scope.
5.
Pull out the
5X
magnifier and
adjust the
HORI-
ZONTAL
POSITION
control
to observe the
leading edge of
either pulse. See
Fig. 6-9.
6.
Check
that the leading edge of
a pulse does not
overlap the
trailing
edge of the previous
pulse.
If
it
does
reposition
30
PG
coil
B
as
follows.
8.
Stop
the
motor
(release the
RECORD
button).
Allow
the heads to stop
turning.
9.
Loosen
the screw securing 30
PG
coil
B,
which
is
mounted
at
the
rear of the scanner,
at
the
12
o'clock position. See
Fig. 6-8.
10.
Move
30
PG
Coil
B
slightly to the
left
or right.
11. Start the
motor
again
and check
the
waveform
in Fig. 6-9.
12.
Repeat
Steps 8 to
1 1
until the correct condition
is
obtained.
6-10.
SERVO-REFERENCE DELAY MV
(REC)
The
servo-reference delay multivibrator
(MM401)
adjusts the precise angular position of heads with
reference to the
vertical
sync
pulse.
Test
Point/
Board: TP-403/SV
(Delayed 30
PG
pulse
output)
Adjust
for:
A
pulse
width
of
930
jusec.
See
Fig.
6-10.
TP-403
T
±
3
LI
6
±
1
V
—
•)
r
p—
scope
:
0.5
ms/cm
T=930jJs
Fig. 6-
10.
Delay
multivibrator adjustmen
t
(REC
mode)
Adjustment/
Board: R413/SV
(Lock
Phase)
6-6