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7. FINE ADJUSTMENT
OF GRATING AND TRK BALANCE ADJUSTMENT
[Mechanical Adjustment]
® Purpose:
Fine adjustment of the grating to direct the two TRK
servo laser beams at the disc at the optimum
position over the track.
® Symptom when incorrectly adjusted : There is track skipping.
Measurement equipment
Measurement equipment
Player condition
Adjusting points
& jigs
connecting points
® Oscilloscope
[ ® Oscilloscope
®@ Test mode
@ Grating screw on the
@ Test disc (GGV1003)
CH1 (X): Between
PLAY mode
mechanical Ass'y
® Blade screwdriver
TRK error (CN301-9)
* TRK servo loop open
@L.P.F. (0.01pF, 1K)
and GND.
» TILT servo ON
@ VR602
(0.0027F)
CH2 (Y): TRK sum
(CN301-8)
Adjusting procedure
1. Playback the disc at frame #3000 (inner periphery) or
thereabouts.
2. Set the oscilloscope to the X-Y mode, and connect CN
301-9 (TRK error) and CN301-8 (TRK sum) to the X
input and the Y input respectively. Then look at the
resurge waveform.
3. Insert
the
blade
screwdriver
tip into
the
grating
adjustment hole. Adjust the grating to minimize the Y
direction of the resurge waveform. (Refer to adjustment
diagram on page 11.)
4. Check if a equals b for the resurge waveform. If a is not
equal to b, adjust VR602 (TRK balance).
5. Close the TRK servo loop and check if the image on the
TV screen is normal.
Pajdatnscttt diaetals
* Oscilloscope range:
Oscilloscope
CH1(X): 50mV//div
CH2(Y): 5mV/div
Mother Board Assembly
Set the probe to mul only for Y.
Frame #2000
Resurge waveform
Y direction minimum, a=b.
16
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