Sony CDX-4240R Service Manual page 19

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 MQ 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.
oscilloscope
SERVO board
ee [Fu]
TP (RF) «—___-_—___o+
TP (RF. GND) «<———_—!o--
Procedure:
1. Connect an oscilloscope between TP (RF) and TP (RF. GND)
on the SERVO board.
Connect the power supply.
Push the RESET] button (S900) on the MAIN board.
Insert the disc (YEDS-18) and playback.
Adjust RV 1 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.
12 SoD
VOLT/DIV: 200 mV
TIME/DIV: 500 nS
FF signal waveform
WV iY
level: 1.0 — 1.5 Vp-p
¢ 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
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)
FOCUS GAIN ADJ
RV4
°
TP
(RF. GND)
RVI
FOCUS BIAS ADJ
4G