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LD-V4300D
7. PICK-UP ASSEMBLY CENTERING ADJUSTMENT
• Purpose: To adjust so center
of
the
spindle
motor comes on the
track of
the laser
beam.
• Symptoms when incorrectly adjusted: Track jumping, longer search
lime.
Measurement equipment
&Jigs
• Oscilloscope
• Short-shaft
hcxaaonal
wrench (2 mm)
or,
L-shapcd
hexagonal
wrench
• Test disc:
GGV1003
Adjusting procedure
Measurement equipment
connecting points
•
Oscilloscope:
[n FTSB
assembly
CHl(X):
Between
TP!-9 (TRKG
Error)
and
GND
CH2
(Y): TPI-4 (TRKG
A+C)
Note:
This adjustment should
be performed
only
when the pick-up
assembly
is insufficiently
adjusted by the "6. Pick-up
assembly
center-
ing check".
rs.,,
pags 1 14}
1. Connect the X-input (CHI)
of the oscilloscope
to
TPl-9 (TRKG ERROR)
in
FTSB assembly and Y-
input
(CH2)
to
TPl-4
(TRKG
A
+C)
respectively.
2.
Play the
test
disc
and search for
frame
#
20,000
using
the SCAN FWD key
to move
the
pk k·up
towards the
outside of
the disc.
3.
Open
the
tracking
servo, and
observe
the
Lissajous
waveforms
of the
TRKG
error
signal and
the TR.KG
A
+
C
signal.
4.
Fine
adjust
the
grating
so
lhat
lhe
Y-axis
amplitude
of the Lissajous waveform
becomes
minimum.
(Photo
7)
5. Close the TRKG servo and
mo\':
1he
pick-up
toward
the inside of the disc by pressing the SCAN REV key.
6.
Open
the TRKG servo again, and
observe
the
Adjustment diagram
Fig. 7-1
Player condition
•
Service
mode:
• Play
mode
• Tracking
servo
loop
open/
close
•
Till servo
OFF
Adjusting points
•
Centering
adjustment
screw
in
the
pick-up
assembly
Lissajous
waveform and record
its Y-axis
amplitude.
7. Move the
pick-up t
oward outside
again, and rotate 1he
centering
adjustment
screw
clockwise by 45° with the
hexagonal
wrench
.
(Fig
.
7-1)
Rotate the
centering
adjustment screw slowly so that the
Y-axis amp1itude
of
the Lissajous
waveform
decreases.
After the
Y-axis
amplitud
e
of the Lissajous
wavefonn
becomes
minimum,
rotate
the hexagonal wrench
further
in
the
same direction
until
the
Y-axis
amplitude
of
the
Lissajous
waveform
becomes
the
same
level
as
the
recorded
one
in
m:p 6.
(Photo
6 -
8)
8.
Close the TRKG
servo
a nd move the
pick-up toward
the
outside
of the disc
using the
SCAN FWD
key.
9.
Repeat
the
operation
in
steps
3, 4 and
5.
10.0pcn the
TRKG
servo again
to
observe
the Lissajous
waveform, and
check
that the Y-axis amplitude is
minimum.
If
the Lissajous waveform is
expanded
in the Y-axis
direction,
repeat t
he
operation in steps
7,
8, 9, and 10.
I
CN4'
--
- - - ,
., 0
D
"'
o
Cl
[)
0
0
0
-
0
11
1
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