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DV-NC55U/C/M
8-21. ADJUSTMENT OF TAPE DRIVE TRAIN
1. Tape run rough adjustment
1 Remove the cassette housing control assembly.
2 After short-circuiting between TP5102 and TP5103
provided goes left at VTR display PWB, plug in the
power cord.
3 Check and adjust the position of the tension pole.
(See 8-15.)
4 Check and adjust the video search rewind back
tension. (See 8-13.)
5 Connect the oscilloscope to the test point for PB
CHROMA signal output (TP1201). Set the synchro-
nism of the oscilloscope to EXT. The PB CHROMA
signal is to be triggered by the head switching pulse
(TP1202).
6 Set the alignment tape (VROATSV) to play. (Put a
500g weight on the cassette tape to prevent lift of
cassette tape.)
Guide roller
7 Press the tracking button (+), (–) and change the
ATR signal waveform from max to min and from min
to max. At this time make sure that the ATR signal
waveform changes nearly parallel.
8 Unless the ATR signal waveform changes nearly
parallel, adjust the height of supply side and take-up
side guide roller so that the envelope waveform
changes nearly parallel. (For ATR signal adjustment
procedure refer to Figure 8-35.)
9 Turn the tilt screw to remove the tape crease at the
fixing guide flange.
Playback the tape and check for tape crease at the
fixing guide flange.
(1) If there is no tape crease
Turn the tilt screw clockwise so that tape crease
appears once at the flange, and then return the tilt
screw so that the crease disappears.
(2) If there is tape crease
Turn counterclockwise the tilt screw so that the
tape crease disappears.
(Reference) If the tilt screw is turned clockwise
crease appears at the lower flange.
Cassette Tape
500g
Weight of 500g
Figure 8-31.
Notes:
1. Previously set the tracking control in the center position,
and adjust the ATR signal waveform to maximum with X
value adjustment nut. Thereby the tape run rough ad-
justment is facilitated.
2. Especially the outlet side ATR signal waveform must
have higher flatness.
2. Adjustment of A/C head height and azimuth
1 Perform the initial setting of A/C head position by the
method stated in "8-18 Replacement 3".
2 Connect the oscilloscope to the audio output termi-
nal.
3 Using the alignment tape in which 1 kHz linear audio
signal has been recorded, adjust the height screw so
as to get max audio output.
4 Using the alignment tape in which 7 kHz linear audio
signal has been recorded, adjust the azimuth screw
so as to get max audio output.
5 The adjustment of 3 and 4 twice or three times
repeat, and finally adjust 4.
3. Tape run adjustment
1 Connect the oscilloscope to PB CHROMA signal
output test point, set oscilloscope sync to EXT,
trigger-input the PB CHROMA signal (head switch-
ing pulse).
2 Rough adjustment of X value
Tentatively fix A/C head arm screws 1 and 2 by the
method described in 8-18 "Replacement 3".
Playback the alignment tape (VROATSV) and
shortcircuit between TP5101 and TP5103. As a
result the auto-tracking is automatically cancelled,
so that the X value adjustment mode is set.
Move the A/C head with the X value adjustment gear
driver (JiGDRiVER-6) by the method shown in Fig-
ure 8-33, and adjust the A/C head so as to get the
maximum ATR signal waveform. (Note: When the A/
C head is adjusted, adjust so that the maximum ATR
signal waveform is obtained nearest the position of
initial setting made in 8-18.)
30
Figure 8-32.
For X value adjustment
Adjust the X value, turning the gear-
type screwdriver.
Figure 8-33.
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