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2. ADJUSTMENT AFTER REPLACING THE CYLINDER
(VIDEO HEADS)
When the cylinder
is replaced,
the relative
height with respect
to the guide rollers or the
X-value,
etc.
drifts
(this drift
is smallwhen the
cylinder
is replaced correctly).
Therefore,
it is necessary
to readjust the tape
transport
system and servo system.
Perform
checks and adjustments by the following steps.
Note:
For the X-value adjustment,
refer to the
service manual
(electrical
adjustment)
issued for each model,
1) Load a blank tape and play it.
Check that no
curling or creasing occurs
around the guide
rollers.
If curling or creasing occurs,
fine
adjust the height of the guide rollers.
2) Confirm that the FM envelope is flat and
level
fluctuations
are minimum.
If it cannot
be confirmed,
adjust
the
height of the guide rollers.
See the next
item for these checks.
3) Check or/and adjust the head switching point.
(Refer to the service manual
(electrical
adjustment)
issued for each model.)
4) Confirm that the X-value adjustment
is correct.
If it cannot
be confirmed,
adjust the X~ value.
Check Flatness and Level
Fluctuations
of the
FM Output
1) Connect
an oscilloscope
to test point of FM
envelope.
2) Trigger the oscilloscope
at SW30Hz.
3) Set the TRACKING control
to center position.
4) Playback the alignment
tape.
5) Adjust
the voltage
level control
on the
oscilloscope
so the maximum amplitude of the
FM output
is 4 graduations
on the oscilloscope.
6) Adjust
the tracking control buttons so the
maximum amplitude of the FM output
is 3
graduations
on the oscilloscope.
7) Check that the minimum amplitude
is more than
2 graduations.
If this cannot be confirmed,
fine adjust the height of the guide rollers.
3. TENSION AND TORQUE CHECKS
It is necessary
to check the tension,
torque and
compression strength
in the tape take-up section
and moving section to smoothen the tape transport
and to satisfy the basic performance
of the VCR.
When the tape transport
is not smooth or the tape
speed is abnormal,
detect the faulty section by
this checking,
and then check again after
replacing
the faulty parts with normal ones
to
complete the work.
E2- 5
in
+
ad
x A
4 GRADUATIONS
SGRADUATIONS
— 2GRADUATIONS
cine
Fig. 2-1
TORQUE GAUGE
TORQUE GAUGE
ADAPTER
REEL DISK
Fig. 3-1
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