Mitsubishi Electric HS-U449 Service Manual page 46

3-3. A/C HEAD Adjustment
3-3-1. Slant Adjustment of A/C HEAD
1. Play back a blank tape.
2. Slowly turn Screw C shown in Fig. 3-3-1 counter-
clockwise to slightly crease the bottom of the tape at
the lower flange of the GUIDE POLE (TU).
3. Slowly turn Screw C clockwise to remove the crease.
4. Slowly turn Screw C counter-clockwise again and stop
just before the tape is creased.
3-3-2. Azimuth and Height Adjustment of
A/C HEAD
1. If the height of the CONTROL HEAD is different from
the specified value shown in Fig. 3-3-2, realign it with
Screw A, B, and C in Fig. 3-3-1.
2. After realigning Screw A, B, and C, repeat "3-3-1.
Slant Adjustment of A/C HEAD."
3. Connect the oscilloscope to the audio output terminal.
4. Play back an alignment tape (NM6KE2 : 859C339O90).
5. Turn Screw B for the azimuth adjustment shown in
Fig. 3-3-1 to set the audio output level to maximum as
shown in Fig. 3-3-3. After the adjustment, remove the
screwdriver and make sure that the audio output level
is 4.6 or over on the oscilloscope with the maximum
audio output level set to 5. If the audio output level is
less than 4.6, repeat this adjustment from the
beginning.
6. Make sure that the audio output level 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. 3-3-1) and released. (Do not push the A/C HEAD
before the audio output level drops to 3/4 or less of its
maximum level.)
7. Make sure that the audio output level varies by 2 dB
or less in the PLAYBACK mode.
8. If the variation in the audio output level exceeds 2 dB,
repeat "3-3-1. Slant Adjustment of A/C HEAD."
9. If the height of the CONTROL HEAD isn't set to the
specified value, replace the TAPE GUIDE ASSY (SP)
and the TAPE GUIDE ASSY (TU) in accordance with
"2-32. TAPE GUIDE ASSY (SP), TAPE GUIDE ASSY
(TU)."
Screw C
A
Tape
Screw A
Screw B
AE HEAD
CONTROL HEAD
6kHz Audio Output Signal
- 33 -
a
A'
Fig. 3-3-1
AUDIO HEAD
0.0 mm
0.25±0.03 mm
Reference Line
Fig. 3-3-2
Maximum
Fig. 3-3-3