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9. TRK SERVO LOOP GAIN ADJUSTMENT
®@® Purpose:
Optimum setting of the TRK servo's loop gain.
@ Symptom when incorrectly adjusted:
Playability is poor.
[Mechanical Adjustment]
Measurement equipment
& jigs
Measurement equipment
connecting points
Player condition
Adjusting points
® Oscilloscope
® Test disc (GGV1003)
@ AF oscillator
(3.0kHz/10 Vp-p)
® Resistor(47k2)
® Oscilloscope
CH 1(X): CN301-10
(TRK IN)
CH 2(Y): CN301-9
(TRK ERR)
® Test mode
+ Still at frame #15000
*- TRK
servo closed.
+ Tilt servo ON
@® VR603
(Black screen)
Adjusting procedure
1. Search for frame #15000 on the test disc.
2, Connect CN301-10(TRK IN) and CN301-9(TRK ERR)
. Adjust
as shown in the diagram below.
. Set the oscilloscope to the X-Y mode and watch the
resurge waveform.
VR603
to
make
the
resurge
waveform
symmetrical
with respect to the X and Y axes.(See
Photos 1 and 2.)
: Note:
If the adjustment
cannot
be made,
either set the
47k
resistor to 33kN
or increase
the oscillator's
output.
Adjustment diagram
18
Mother Board Assembly
Photo 1 Inadequate adjustment.
AF Oscillator
Oscilloscope
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