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2.
COARSE ADJUSTMENT
OF GRATING AND TRK BALANCE ADJUSTMENT
[Mechanical Adjustment]
@ Purpose:
Adjustment of the grating angle to enable disc playback and trick playback.
@ Symptom when incorrectly adjusted: The disc cannot be played back. Track skipping occurs.
Measurement equipment
Measurement equipment
& jigs
connecting points
Player condition
Adjusting points
@ Blade screwdriver
® Oscilloscope
@ Test disc (GGV1003)
®TV monitor
® Oscilloscope
@ Test mode
Between CN301-9
(TRK
ERR) and GND.
@ Pickup Ass'y grating
* Disc playback
* TRK servo open
+ Tilt servo OFF
@ VR602 (TRK BAL)
Adjusting procedure
[Coarse grating adjustment]
: {TRK balance adjustment]
1. Insert the test disc and press the PLAY key.
: 1. Adjust
VR602
so
that
the
TRK
error
waveform
2. Search for frame #15000 or thereabouts.
>
amplitude's positive and negative level become
equal.
3. Open the TRK servo.
:
(See Photo 3.)
4. Connect
CN301-9 to the oscilloscope and observe the
;: 2. Close the TRK servo and check if the image on the TV
waveform.
:
screen is normal.
5. Slide the tip of a small blade screwdriver through the
|
guide
and
insert
it horizontally
into
the
grating
: Note: Set the oscilloscope's time axis range to the maximum
adjustment hole. Look for the null point. (See Fig. 1
:
~
and watch the TRK error waveform. The compressed
and Photo 1.)
waveform
will
then
appear.
This
will
make
the
6. Turn the screwdriver counterclockwise until the TRK
adjustment easier.
waveform's amplitude reaches the first maximum
from
the null point. (See Photo 2.)
This is not the null point.
Adjustment diagram
(Top view)
\
Screwdriver inserting direction
ae
(Maximum time axis range.)
Photo 2 Maximum TRK error.
Photo 3 The positive and negative
levels are equal.
Insert the screwdriver to the slot
horizontally for the base
41
3.
SLIDER SHAFT HORIZONTAL
ADJUSTMENT
[Mechanical
Adjustment]
® Purpose:
Setting the slider shaft horizontally to enable the pickup to move over the disc horizontally.
® Symptom when incorrectly adjusted:
With a warped disc, the FCS servo does not function at the inner or outer
periphery.
Measurement equipment
Measurement equipment
Player condition
Adjusting points
& jigs
connecting points
®@ Oscilloscope
® Between CN301-3
@ Test mode
® Player SKIP key
@ Low-pass filter
(FCS RTN) and GND.
* #5200 still
(During test mode)
(47K 1pF)
* TRK servo open
* Tilt servo OFF
® Test disc (GGV1003)
i
Adjusting procedure
1. Use the SCAN key to send the slider to frame #5200 or
: Note:
This adjustment is critical in that it will affect the
thereabouts (tilt fulcrum) on the test disc. Open the
:
adjustments following.
TRK servo.
2. Connect
CN301-3
to the oscilloscope
through
L.P.F.
and
match
the
center
of the
waveform
with
the
oscilloscope's GND.
3. Search for frame
#25000
and use the SKIP
key to
adjust the center of the waveform to OV.
Note:
Regarding the test mode, see page 6.
Adjustment diagram
Oscilloscope
Frame #5200 or thereabouts
Pick-up
assembly
Skip Key (=a
er}
Oo
00
Tilt sensor
(#5200)
Spindle motor
Frame #25000 or thereabouts
12
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