Mitsubishi Electric HS-U449 Service Manual page 44

3-2-4. Coarse Adjustment of Phase
1. Play back an alignment tape (NM6KE2 : 859C339O90).
2. Preset the tracking.
3. Check the FM waveform after performing "3-2-1.
GUIDE ROLLER Adjustment Check."
4. If the amplitude level of the FM waveform is low as
shown by Waveform (F) in Fig. 3-2-4, set it to
maximum as shown by Waveform (G) using the
following procedure. Loosen the screws D and E.
Insert a Phillips screwdriver into the hole in the MAIN
PLATE ASSY (Part A) and move the A/C PLATE from
side to side to set the amplitude level to maximum.
5. Tighten the screws D and E.
3-2-5. Flatness Check of FM Waveform
1. Play back an alignment tape (NM6KE2 : 859C339O90).
2. Adjust the tracking and confirm that the amplitude of
the FM signal remains flat.
Note : Press the tracing (+)and (–) button during play
back to adjust tracking.
3. Adjust the tracking so that the amplitude level of the
FM waveform is at maximum. Set the oscilloscope so
that the amplitude level of the FM waveform is 5
divisions on the oscilloscope.
4. Adjust the tracking so that the peak of the FM output
waveform is 4 divisions. Make sure that FM
Waveforms (B), (C), (D), and (E) are within the range
of the specified values in Fig. 3-2-5.
5. If the waveforms are out of the specified ranges,
repeat "3-2. Check and Adjustment of the FM
Envelope" from the beginning.
Screw D
Tape
Screw E
Part A
(F)
(G)
B D
0.2 division
B, C
D, E
- 31 -
Fig. 3-2-3
Fig. 3-2-4
E
4 divisions
0.2 division
In VHS mode
2.5 divisions or more
1.0 division or more
Fig. 3-2-5
C