Sharp 27DV-S100 Service Manual page 38

27DV-S100
27DV-CS10
3 Next, change the alignment top to VROEFZCS to
play back. 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 en-
velope 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 1-35.
5 Press the tracking button (+), (–) and make sure
that the envelope waveform changes nearly paral-
lel.
6 Finally check tape crease near the reverse guide. If
tape crease is found, remove it as stated in page 36
"HEIGHT ADJUSTMENT OF REVERSE GUIDE"
item 3.
Adjustment
3 Move the A/C head with the X value adjustment
gear driver by the method shown in Figure 1-33,
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 37, 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.
When the tape is above the helical lead.
Supply side
Supply side guide roller Take-up side guide roller
rotated in clockwise rotated in clockwise
direction (lowers guide direction (lowers guide
roller) to flatten roller) to flatten
envelope. envelope.
Figure 1-35.
PB CHROMA
Envelope
4. A/C head X value adjustment
1 Tentatively fix A/C head arm screws 1 and 2 by the
method described in page 35 "Replacement 3".
2 After shortcircuiting R7057 and JUMPER:420, plug
in the powercord, then turn off the power. And set
the alignment tape (VROEFZCS) into the unit, turn
on the power, then playback it. As a result the auto-
tracking is automatically cancelled, so that the X
value adjustment mode is set.
When the tape is below the helical lead.
Take-up side Supply side
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.
• Problems caused by maladjustments
1. Totally maladjusted
• Tapes may get scratched.
• Images onscreen may get distorted or affected by
noises, or may fail to appear.
• The linear audio level may get degraded.
Note:
When the A/C head X value adjustment is performed, be
sure to perform at first X value rough adjustment (refer to
page 37, 3-2).
2
38
CH-1 CH-2
Head switching pulse
Figure 1-34.
Take-up side
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.
1
Figure 1-36.