Panasonic PV-M1348 Service Manual page 46

2. AUDIO CONTROL HEAD TILT ADJUSTMENT
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 Audio Control 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 check that the tape
travels smoothly between the upper and lower guides of the
P4 post.
2. If necessary, adjust Black Screw (B) clockwise until the
tape begins to curl at the lower edge of the P4 post. Then
adjust the screw counterclockwise until the curling is
eliminated.
Audio Control
Tape Running
Head in Tilted
Condition
Condition
Fig. M7
3. AUDIO CONTROL HEAD HEIGHT
ADJUSTMENT
The height of the Audio Control Head replacement part is
preset 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 Audio Control Head is
replaced.
1. Play back a T120 cassette tape and check that the lower
edge of the tape runs approximately 0.25 mm above the
lower edge of the Audio Control Head.
2. If necessary, adjust Black Screws (A) and (B) clockwise to
lower the tape or counterclockwise to raise.
Control Head
Direction to
turn for
Correction
4. AUDIO CONTROL HEAD AZIMUTH
ADJUSTMENT
Purpose:
To adjust the position and height of the Audio Control Head
so that it meets the tape tracks properly.
Symptom of Misadjustment:
If the position of the Audio Control Head is not properly
adjusted, the Audio S/N Ratio is poor.
1. Connect the oscilloscope to the TP4002 on the Main C.B.A.
2. Play back the 6kHz Monaural Audio portion of the alignment
tape.
3. Adjust Black Screw (C) on the Audio Control Head base so
that the output level is at maximum.
4. Confirm the height of the Audio Control Head is proper. If
not, readjust Black Screws (A) and (B).
2-23
Black Screw (B)
Lower Edge
of Tape
Lower Edge
of Control Head
Fig. M8
6KHz-Audio
Fig. M9
Black Screw (C)
Black Screw (A)
0.25mm
Maximum