– 21 –
IC3
CN2
CN1
IC1
FOCUS GAIN ADJ
RV4
TP
(RF. GND)
IC2
TP
(RF)
CN3
RV1
FOCUS BIAS ADJ
RF signal waveform
VOLT/DIV: 200 mV
TIME/DIV: 500 nS
level: 1.0 – 1.5 Vp-p
+
–
SERVO board
TP (RF)
TP (RF. GND)
oscilloscope
CD SECTION
Note:
1. CD Block basically constructed to operate without adjustment.
Therefore, check each item in order given.
2. Use YEDS-18 disc (3-702-101-01) unless otherwise indicated.
3. Use the oscilloscope with more than 10 M
Ω
impedance.
4. Clean an objective lens by an applicator with neutral detergent
when the signal level is low than specified value with the following
checks.
Focus Bias Adjustment
Setting: This adjustment is performed with the set placed
horizontally.
Focus Gain Adjustment (Coarse adjustment)
This adjustment is not required unless the following parts are replaced:
•
Optical pick-up
•
RV4
Procedure:
1. Set RV4 to the standard position. (mechanical center)
2. Check whether operation noise (while noise type) caused by
the 2-axis device (lens section of the optical pick-up) is
abnormally loud.
If the operation noise is too loud, turn RV4 slightly counter-
clockwise.
•
If the gain is too low:
Focus does not function and no music is selected.
•
If the gain is too high:
Noise caused by scratches and dust is heard and the operation
becomes unstable.
Adjustment Location: servo board
Adjustment Location: servo board (component side)
Procedure:
1. Connect an oscilloscope between TP (RF) and TP (RF. GND)
on the SERVO board.
2. Connect the power supply.
3. Push the RESET button (S900) on the MAIN board.
4. Insert the disc (YEDS-18) and playback.
5. Adjust RV1 so that the oscilloscope waveform is clear and check
RF signal level is correct or not.
Note: Clear RF signal waveform means that the sharp “
≈
” can be
clearly distinguished at the center of the waveform.
• When observing the eye pattern, set the oscilloscope to AC range
and raise the vertical sensitivity so that it may be easily seen.
Adjustment Location: servo board
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