Sony PMC-D305, Руководство по обслуживанию

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Focus Bias Adjustment
This adjustment is to be done when the optical pick-up is replaced.
Procedure:
1. Connect the oscilloscope TP (RF) and TP (VC) on the CD board.
2. Insert the disc (YEDS-18) in and close the lid for CD.
3. Put the set into test mode. (See page 30.)
4. Press
+
and
=
buttons to move the optical pick-up to the
center. (Move the optical pick-up to the music area on the disc
to enable easy visibility of the eye pattern.)
5. Press the
(
button.
From focus searching, focus is turned ON while entering
CLV drawing-in mode. Tracking and sled are turned OFF.
6. Press the
(
button.
[Both tracking and sled are turned ON.]
7. Adjust RV701 so that the oscilloscope waveform is as shown in
the figure below. (eye pattern)
A good eye pattern means that the diamond shape (
≈
) in the
center of the waveform can be clearly distinguished.
• RF signal reference waveform (eye pattern)
VOLT/DIV : 0.2 V (With the 10:1 probe in use)
TIME/DIV : 500 ns
1.3
±
0.2 Vp-p
+
–
CD board
TP (RF)
TP (VC)
Oscilloscope
(AC range)
When observing the eye pattern, set the oscilloscope for AC
range and raise vertical sensitivity.
8. Release the test mode after adjustment is completed.
Adjustment Location: CD board (See page 33.)
Gain
Focus Tracking
Symptoms
• The time until music starts becomes
longer for
p
→
(
on automatic
selection. low low or high
(
=
,
+
buttons pressed.)
(Normally takes about 2 seconds.)
• Music does not start and disc
– low
continues to rotate for p
→
( or
automatic selection.
(
=
,
+
buttons pressed.)
• Sound is interrupted during PLAY.
Or time counter display stops – low
progressing.
• More noise during 2-axis device
high high
operation.
Focus/Tracking Gain Adjustment
A frequency responce analyzer is necessary in order to perform
this adjustment exactly.
However, this gain has a margin, so even if it is slightly off, there
is no problem. Therefore, do not perform this adjustment.
Focus/tracking gain determines the pick-up follow-up (vertical and
horizontal) relative to mechanical noise and mechanical shock
when the 2-axis device operate.
However, as these reciprocate, the adjustment is at the point where
both are satisfied.
• When gain is raised, the noise when the 2-axis device operates
increases.
• When gain is lowered, mechanical shock and skipping occurs
more easily.
• When gain adjustment is off, the symptoms below appear.
REFERENCE