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6. INSPECTION AND ADJUSTMENT OF SPINDLE MOTOR CENTERING
® Purpose:
Adjustment of the mechanical Ass'y position to set the spindle motor over the center of the laser beam
path when the pickup Ass'y moves toward the inner or outer periphery of the disc.
© Symptom when. incorrectly adjusted: There is track skipping and the search time is long.
[Mechanical Adjustment]
Measurement equipment
& jigs
Measurement equipment
connecting points
Player condition
Adjusting points
@ Oscilloscope
@ Test disc (GGV1003)
®@ Blade screwdriver
@L.P.F. (0.01uF, 1K)
(0.027 uF)
® Oscilloscope
CH1: CN301-9
(TRK ERR)
CH2: CN301-8
(TRK SUM)
@ Test mode
+ #£25000 still
#1 still
* TRK servo open
- TILT servo ON
@ Spindle motor centering
adjustment lever
Adjusting procedure
: 5. Change
to a compact
disc and
playback
the inner
periphery. Check if the resurge waveform is the same as
:
the one shown in Photo 1.
2. Search for frame #25000 on the test disc and look at
6. If the compact disc's inner periphery resurge waveform
the resurge waveform.
differs from the one shown in Photo 3, repeat steps 4 to
3. Search
for frame
#1 and check
if the bulge of the
:
5.
resurge waveform is the same as that of frame #25000's_
:
resurge waveform.
Note:
If the bulge of the resurge waveform in step 3 differs
for the inner and outer peripheries, do steps 4 to 6 as
follows.
4. Search for frames
#25000 and #1 alternately. Adjust
the spindle motor
centering adjustment
screw so that
the resurge waveforms match.
1. Set the oscilloscope to the X-Y mode and connect CN
301-9 and CN301-8 to CH
1 (X input) and CH 2 (Y
input) respectively.
Adjustment diagram
Oscilloscope
Shaft adjustment
Shaft fixing
screw
Photo 1 Frame #25000 resurge
Photo 2. Frame #1 resurge
X-Y mode
CH1: 50mV/div
CH2:
5mV/div AC
Photo 3 CD inner periphery resurge waveform.
15
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