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LD-V4300D
12.TRACKING SERVO LOOP GAIN ADJUSTMENT
• Purpose: To set the loop gain
of
the TR.KG (tracking) servo to the optimum
value.
• Symptoms when incorrectly
adjusted:
Play ability grow worse.
Measurement equipment
& jigs
• Oscilloscope
• Test disc:
GGV1003
• AF
oscillator
•
Resistance
(lOO kO)
Adjusting procedure
Measurement equipment
connecting points
•
OsdUoscope:
In FTSB
assembly
CHI
(X):
Between
TP!
-7 (TRKG ERR
IN)
with
I00kCl
and
GND
CH2
(Y):
TPI -9
(TRKG ERR OUT)
I
.
Play the test disc and search for frame
#
15,000.
2.
Connect
the X and Y terminals
of
the oscilloscope as
shown in Fig. 12-1, and observe the Lissajous's
waveforms.
3. Adjust VR3
so
that the Lissajous's
waveform
as
shown
in
Photo
15
appears.
Photo
14 shows
a
waveform
when
the adjustment
is incorrect.
Adjustment diagram
o@
QD
118
@
0
0
oo
0
ESla
Fig.
12-1
Oacilloscope
0
Player condition
Adjusting points
• Normal mode:
•
VR3in
the
FTSBassembly
•
Still mode
• TILT
servo
OFF
Waveforms
• Oscilloscope
range:
X-Y
mode
X: 0.2mV/div.
DC
input
Y: lOmV/div.
DC inpUI
Weveformwh•
n
insufficiently1djust•d
Photo14[11
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· ';
.·•.
.
.
'
~
:·
"
..
·.·
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.
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.
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,
,
...
1
I
D
Pho,o
151
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