Sony PMC-107, Руководство по обслуживанию

Страница: 17 / 51

– 17 –
0V
1.3
±
0.2 V
VOLT / DIV : 0.2 V
TIME / DIV : 500 nS
oscilloscope
(DC range)
CD board
TP (RF)
TP (VC)
Gain
Symptoms
Focus Tracking
• The time until music starts becomes longer
for
π
m fl
on automatic selection.
low low or high
(
≠
,
±
buttons pressed.)
(Normally, takes about 2 seconds.)
• Music does not start and disc continues
to rotate for
π
m fl
or automatic
– low
selection.
(
≠
,
±
buttons pressed.)
• Sound is interrupted during PLAY. Or
– low
time counter display stops progressing.
• More noise during 2-axis device
high high
operation.
Focus Bias Adjustment
This adjustment is to be done when the optical pick-up block is
replaced.
Procedure :
1. Connect the oscilloscope between TP (RF) and TP (VC).
2. Insert disc (YEDS-18) and push the
fl
button.
3. Adjust RV701 so that the oscilloscope waveform is maximum as
shown in the figure below (eye pattern).
• RF signal reference waveform (eye pattern)
REFERENCE
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 raised, the noise when the 2-axis device operates
increases.
• When gain is lowered, it is more susceptible to machanical shock
and skipping occurs more easily.
When gain adjustment is off, the symptoms below appear.
When observing the eye pattern, set the oscilloscope for AC range
and raise vertical sensitivity.
Adjustment Location : See page 19.