Sharp VC-A598U, Service Manual

Page: 24 / 90

VC-A598U/H995U/H996U
-H997U/H9977U/H998U
24
3
Next, change the alignment tape to VROEFZCS or
VROEFZHS to playback. Press the tracking button
(+), (–) and change the envelope waveform from
max to min and from min to max. At this time adjust
the height of supply and take-up side guide roller with
the adjustment driver (JiGDRiVERH-4) so that the
envelope waveform changes nearly parallel.
4
If the tape is lifted or sunk from the helical lead
surface, the PB CHROMA envelope waveform ap-
pears as shown in Figure 4-35.
5
Press the tracking button (+), (–) and make sure that
the envelope waveform changes nearly parallel.
6
Finally check tape crease near the reverse guide. If
tape crease is found, remove it as stated in Page 22
"HEIGHT ADJUSTMENT OF REVERSE GUIDE"
item 3.
3
Move the A/C head with the X value adjustment gear
driver by the method shown in Figure 4-33, and
adjust the A/C head so as to get the maximum
envelope waveform. (Note: At this time adjust so as
to get the maximum envelope waveform nearest the
A/C head position which has been set in case of X
value rough adjustment as stated in Page 23, 3-
2
.)
4
Tighten finally the screws
1
and
2
. Be sure to
tighten at first the screw
1
and then the screw
2
.
Final tightening torque is 0.6N·m (If the screw
2
is
tightened first, the X value may deviate.)
5
Adjust the playback switching point (Refer to the
electric adjustment method.)
6
Playback the self-picture-recorded tape, and check
the flatness of envelope waveform and sound.
Notes:
When the A/C head X value adjustment is performed, be
sure to perform at first X value rough adjustment (refer to
Page 23, 3-
2
).
PB CHROMA
Envelope
CH-1 CH-2
Head switching pulse
Figure 4-34.
4. A/C head X value adjustment
1
Tentatively fix A/C head arm screws
1
and
2
by the
method described in Page 21 "Replacement 3".
2
Playback the alignment tape (VROEFZCS or
VROEFZHS), and shortcircuit TP802. As a result the
auto-tracking is automatically cancelled, so that the
X value adjustment mode is set.
Take-up side Supply side Take-up side
Adjustment
Supply side
Supply side guide roller
rotated in clockwise
direction (lowers guide
roller) to flatten
envelope. Take-up side guide roller
rotated in clockwise
direction (lowers guide
roller) to flatten
envelope. Supply side guide roller
rotated in counterclock-
wise direction (raises
guide roller) to make the
tape float above the helical
lead. The supply
side guide roller is then
rotated in the clockwise
direction to flatten the
envelope. Take-up side guide roller
rotated in counterclock-
wise direction (raises
guide roller) to make the
tape float above the
helical lead. The take-up
side guide roller is then
rotated in the clockwise
direction to flatten the
envelope.
Figure 4-35.
When the tape is below the helical lead. When the tape is above the helical lead.
1
2
Figure 4-36.