Playback Servo Check; 30 Pg Pulse Position Check - Sony AV-3600 Service Manual

Adjust
for:
Minimum
lock-in
time
when
the
Videocorder
is
set
to the
REC/E-E
mode from
a
complete
stop.
Test Point/
Board: TP-406/SV
(CTL
puise output)
Check:
Waveforms
in Fig. 6-6.
TP-406
1
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Fig.
6-5.
Servo response-time adjustment
Fig. 6-6.
Control
track
pulse check
Adjustment/
Board:
Signal
Source:
Equipment
Required:
Procedure:
R451/SV
(Servo
Response Time)
Telecast signal
(1)
Oscilloscope
(2)
TV
monitor
Adjustment:
Signal Source:
None
Telecast Signal
1
.
Set
up
the E-to-E
mode
using a telecast signal.
2.
Connect
the scope to
TP-410.
Set
the time base to
5
msec/ cm.
3.
Set the
Function
Lever
to
STOP
(release the
RECORD
button) and
wait until
the
rotating
head stops turning completely.
Then,
depress the
RECORD
button.
Observe the
waveform on
the scope.
The
PG
pulse will
move up
and
down
a few times
and
then lock
on
the
30
Hz
multivibrator
ramp
as
shown
in
Fig. 6-5.
4.
Adjust
R451
for
minimum
lock-in
time without
hunting.
Repeat Step
3 after
each adjustment
ofR451.
Note:
Clockwise
rotation
of
R451
shortens the
lock-in time,
but
increases
hunting.
Counterclockwise
rotation
decreases
hunting but lengthens lock-in time.
6-7.
PLAYBACK SERVO CHECK
Check
that
the
correct
CTL
(Control track) pulses
are
reproduced for the servo system
in
the
Playback
mode.
Equipment
Required:
(1)
Oscilloscope
(2)
TV
monitor
Procedure:
1.
Make
a
recording of
a
telecast signal.
2.
Play
back
the
tape.
3.
Connect the scope to TP-406 and check
the
waveform shown
in Fig. 6-6.
4.
Confirm
that the picture locks
up
correctly
in
the Playback
mode.
If
the servo
system
does
not
stabilize,
troubleshoot the
CTL
pulse amplifying
circuits.
The following adjustments
in Sees.
6-8
and &9 are
necessary only
when
either
one of
30
PG
coils
Has
been
replaced or repositioned.
6-8. 30
PG PULSE POSITION
CHECK
(30
PG
Coil Position)
Correct
coil
positions
ensure proper switching
between video heads, and
also
ensure
switching at
the
proper time with
respect to vertical sync.
CAUTION
Avoid adjustment of 30
PG
coils
unless tests
indicate that
adjustment must be made.
Test Point/
Board:
TP-304/V1
(Video
signal output)
6-4