Panasonic OmniVision PV-M1326, Service Manual, Page: 21 / 173

2-16
6. CONFIRMATION/ADJUSTMENT OF
ENVELOPE OUTPUT
Purpose :
To achieve a satisfactory picture and secure precise
tracking.
Symptom of Misadjustment :
If the envelope is output poorly, much noise will appear in
the picture. Then the tracking will lose precision and the
playback picture will be distorted by any slight variation of
the tracking control circuit.
Place a jumper between TP6003 and +5V(TP6020) on the
System Control Section of the VCR 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 VCR Main C.B.A.
Use TP6205 as a trigger.
2. Play back the monoscope portion of the alignment tape
(VFMS0001H6). Adjust the height of posts P2 and P3
while watching the scope display so you can make the
envelope as flat as possible.
(V1/V-max
0.7, V2/V-max 0.8)
If adjustment is required, turn the top of the post with a Post
Adjustment Screwdriver. For adjustment of P2 and P3, refer to
“CONFIRMATION OF TAPE TRAVEL,” Page 2-14.
Fig. M17-1
3. When the scope display is as shown in Fig. M17-2, adjust
the height of P2 so that the waveform looks like the one
shown in Fig. M17-4.
Fig. M17-2
4. When the scope display is as shown in Fig. M17-3, adjust
the height of P3 so that the waveform looks like the one
shown in Fig. M17-4.
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(TP6020) on the
System Control Section of the VCR 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 VCR
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.
Model : A,B,C,D,E,H,I,J,L
4. Tighten the Black Screw with 2 Washers (D).
5. Remove the Jumper between TP6003 and +5V(TP6020).
Model : F,G,K
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.
7. If the number of pushes is not the same, then loosen the
Black Screw with 2 Washers (D) and set the H-Position
ADJ. Screwdriver into the Hole (E) shown in Fig. M16.
Then find the center point. Then repeat the above procedure
to determine the center point.
8. Tighten the Black Screw with 2 Washers (D).
9. Remove the Jumper between TP6003 and +5V(TP6020).
Fig. M16
V1
V
V2 V1
Theoretical Waveform
V1/V-max 0.7 V2/V-max 0.8
Dropping envelope level at
the beginning of track (P2)
A/C Head
Black Screw with
2 Washers (D)
Hole (E)