Panasonic OmniVision PV-M1326, Service Manual, Page: 20 / 173

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3. CONFIRMATION OF TILT OF A/C HEAD
Purpose :
To confirm that the tape runs smoothly. In particular,
confirm that the tape properly picks up the Audio Signal at
the upper part of the head and the Control Signal at the lower
part of the head.
Symptom of Misadjustment :
If the tilt of the A/C Head is poorly adjusted, the tape will
eventually be damaged. An intermittent Blue screen may be
seen in Playback.
1. Play back a T120 Cassette tape and confirm that the tape
runs properly between the lower and upper limits of the P4
post. Also confirm that the tape runs smoothly.
2. If adjustment is required, turn Black Screw (B), shown in
Fig. M13, clockwise until curling is apparent at the lower
edge of P4. Then turn Black Screw (B) counterclockwise
until the curling smooths out.
Fig. M14
4. AZIMUTH ADJUSTMENT OF A/C
HEAD
Purpose :
To adjust the position and height of the A/C Head so that it
meets the tape tracks properly.
Symptom of Misadjustment :
If the position of the A/C Head is not properly adjusted, the
Audio S/N Ratio is poor.
1. Connect the oscilloscope to the audio output jack on the
rear side of the deck.
2. Play back the monoscope portion (6KHz, Mono) of the
alignment tape (VFMS0001H6).
3. Adjust Black Screw (C) on the head base, shown in
Fig. M13, so that the output level is at maximum.
Fig. M15
4. Readjust Black Screw (A), shown in Fig. M13, for maximum
output.
5. Disconnect the oscilloscope.
Tape Running
Condition
A/C Head in
Tilted Condition
Direction to
turn for
Correction
Maximum
6KHz-Audio
2. CONFIRMATION OF A/C HEAD HEIGHT
The height of the A/C Head replacement part assembly has
already been adjusted at the factory.
Purpose :
To be sure the tape runs properly along the Control Head.
Symptom of Misadjustment :
If the control signal is not properly picked up, Servo
Operation cannot be achieved. A Blue screen will be seen
in Playback.
This confirmation is required when the A/C Head is replaced
and for a preliminary height adjustment. For final adjustments,
perform “CONFIRMATION OF TILT OF A/C HEAD and
AZIMUTH ADJUSTMENT OF A/C HEAD”.
1. Looking at the lower edge of the Control Head with the
T120 tape in motion, ensure that the lower edge of the tape
runs 0.25mm above the lower edge of the control head.
If it doesn’t, turn Black Screws (A), (B), and (C) slightly in
either direction as necessary to correct it. Turn clockwise
to lower the head and counterclockwise to raise it. When
turning Screws (A), (B), and (C), they must each be turned
the same amount.
Fig. M13
Screw (B)
Screw (C)
Screw (A)
Control Head
Black Line
Lower Edge
of Control Head
0.25mm
Lower Edge
of Tape