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6.2.2.2.
BACK TENSION CONFIRMATION
Purpose:
To fine adjust the Back Tension so that
the tape runs smoothly with a constant
tension.
Symptom of
1) If the tape tension is less than the
Misadjustment:
specified value, the tape cannot come
into proper contact with the Video Heads,
resulting in poor picture playback.
2) If the tape tension is too high, the tape
will soon be damaged.
Measurement Procedure
Equipment
Back Tension Meter (Made in U.S.A.,
Required:
Purchase Locally)
VHS Cassette Tape (120-Minute Tape)
Specification
25 +/- 2.5g
1. Play back a T120 cassette tape from the beginning for
approx. 10 to 20 seconds to stabilize tape movement.
2. Insert a Tension Meter into tape path and measure the back
tension.
3. If the reading is out of specification, make sure that there is
no dust or foreign material between the Tension Band of
Tension Arm Unit and the Reel Table.
If cleaning does not correct the tension measurement,
replace the Tension Spring and the Tension Arm Unit.
Fig. M3-1
Note:
1) Be sure that the three probes of the meter are all in solid
contact with the tape, but not touching any other parts of the
mechanism.
2) It is recommended that measurements be repeated at
least three (3) times because the tension meter is very
sensitive to external vibrations.
6.2.2.3.
FG HEAD GAP ADJUSTMENT
Purpose:
To properly pick up the FG Signal.
Symptom of
If the FG Signal is not properly picked up,
Misadjustment:
Servo Operation cannot be achieved.
Equipment
Oscilloscope
Required:
Specification
0.13 +/- 0.02mm
1. Remove the VCR Chassis Unit and then place it upside
down.
2. Remove the Main C.B.A.
3. Slightly loosen Black Screw (A). Then set the Screwdriver
(#1 or #2 Phillips Driver) into the Hole (A). Turn the
screwdriver counterclockwise until the FG Head touches
the rotor. Then turn it slightly clockwise to the clearance as
specified.
4. Tighten Black Screw (A).
5. Reinstall the Main C.B.A.
37
Fig. M3-2
Fig. M4
PV-9661 / PV-9662
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