Mitsubishi Electric HS-U449 Service Manual page 47

3-4. Phase Adjustment
1. Play back an alignment tape (NC1KS : 859C339O80).
2. Preset the tracking.
3. Loosen Screw D and E shown in Fig. 3-4-1. Insert a
Phillips screwdriver into the hole in the MAIN PLATE
ASSY (Part A) and move the A/C PLATE form side to
side to set the amplitude level of the FM waveform to
maximum. (Adjust the FM waveform to maximum
when the waveform at TP2H is high.
4. Tighten Screw D and E.
5. Play back an alignment tape [NMX : 859C568O60].
6. Make sure that the missing portions of the FM
waveform and the audio waveform appear as shown
in Fig. 3-4-2.
7. If the missing portions are different from those shown
in Fig. 3-4-2, repeat from step 3.
8. Adjust the tracking so that the amplitude level of the
FM waveform is at maximum. Set the oscilloscope so
that the waveform is 5 divisions on the oscilloscope.
9. Preset the tracking.
10. Make sure that the FM waveform on the oscilloscope
is 4.8 divisions or over.
11. If the FM waveform is below 4.8 divisions, preset the
tracking and repeat steps 3 to 10.
12. Make sure that the amplitude of the FM waveform
doesn't vary when the A/C HEAD is pushed in the
horizontal direction (or in the direction shown by the
A-A' line in Fig. 3-4-1) and then released.
13. If the amplitude of the FM waveform varies, check the
fixing position of the A/C HEAD. If the A/C HEAD
UNIT is incorrectly installed, reinstall it referring to "3-
8. A/C HEAD UNIT" and "3-3. A/C HEAD Adjustment"
and repeat "3-4. Phase Adjustment" from the
beginning.
14. Repeat loading and unloading the tape several times
and make sure that the amplitude of the FM waveform
doesn't vary.
3-5. Tape wrinkle check
1. Make sure that there is no wrinkle occurring at the
lower edge of the T-160 tape under the GUIDE POLE
(TU) throughout the operation in the PB/FS mode.
2. Make sure that there is no wrinkle occurring at the
upper edge of the T-160 tape under the GUIDE POLE
(TU) throughout the operation in the PB/FS mode.
Screw D
A
Tape
A
Part
Screw E
FM Waveform
Audio Waveform
Output
Tape
GUIDE POLE (TU)
- 34 -
a
A'
Fig. 3-4-1
Missing Portion
Fig. 3-4-2
GUIDE PIN (TU)
Fig. 3-5