Sony PMC-222V, Руководство по обслуживанию

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Focus Bias Adjustment
This check is to be done when the optical pick-up is replaced.
Adjustment Procedure:
1. Connect the oscilloscope to test point TP (VC) and TP (RF) on
CD board.
2. Insert the disc (YEDS-18) in and close the lid for CD.
3. Press
^
button.
4. Adjust RV701 so that the oscilloscope wavewform 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)
When observing the eye pattern, set the oscilloscope for AC range
and raise vertical sensivity.
Adjustment Location: CD board (See page 27)
Focus/Tracking Gain Adjustment
A frequency response 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, it is more susceptible to mechanical shock
and skipping occurs more easily.
• When gain adjustment is off, the symptoms below appear.
Tracking
Gain
Symptoms
Focus
• The time until music starts
becomes longer for STOP
➡
CD
^
or automatic
selection (
0
,
)
buttons
pressed). (Normally takes
about 2 seconds.)
• Music does not start and disc
continues to rotate for STOP
➡
CD
^
or automatic
selection (
0
,
)
buttons
pressed.)
• Sound is interrupted during
PLAY. Or time counter
display stops progressing.
• More noise during 2-axis
device operation.
low
—
—
high
low or high
low
low
high
VOLT/DIV : 0.2V
TIME/DIV : 500ns
1.1 – 1.5Vp-p
Oscilloscope
(AC range)
+
–
CD board
TP (RF)
TP (VC)
REFERENCE