Panasonic Omnivision PV-4651, Service Manual

Page: 70 / 205

Fig. M15
4. Readjust Black Screw (A), shown in Fig. M13, for maximum output.
5. Disconnect the oscilloscope.
5. HORIZONTAL POSITION ADJUSTMENT OF A/C HEAD
Purpose :
To adjust the Horizontal Position of the A/C Head.
Symptom of Misadjustment :
If the Horizontal Position of the A/C Head is not properly adjusted, a maximum
envelope cannot be obtained at the Neutral Position of the Tracking Control Circuit.
Place a jumper between TP6003 and +5V(TP6009) on the System Control Section of
the Main C.B.A. to defeat Auto Tracking.
1. Eject the tape and insert it again, to access the Neutral Tracking position. Connect
the oscilloscope to TP3002 on the Video Signal Process Section of the Main C.B.A.
Use TP6205 as a trigger.
2. Play back the monoscope portion of the alignment tape (VFMS0001H6) and confirm
that the RF envelope appears, as in Fig. M17-1.
3. If adjustment is required, loosen the Black Screw with 2 Washers (D) and tighten
the Screw lightly. Set the H-Position ADJ. Screwdriver into the Hole (E) shown in
Fig. M16. Then slowly turn the fixture either clockwise or counterclockwise so that
the envelope is at maximum.
4. Before finding the center of the maximum period of the envelope, rotate the fixture
back and forth slightly to confirm the limits on either side of the maximum period.
5. Push the Tracking Control Up Button (on the Remote Control) several times (count
the number of times pushed) until the maximum envelope is reduced to 1/2.
6. Reset the tracking to the neutral position by ejecting the tape and reinserting it.
Push the Tracking control DOWN Button (on the Remote Control) several times
(count the number of times pushed) until the maximum envelope is reduced to 1/2.
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