SONY CDXC4850R
Service Manual

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� 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 TP (RF) TP (RF. GND)
+ �

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 counterclockwise. � 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.
RF signal waveform

IC3 CN2

FOCUS GAIN ADJ RV4

VOLT/DIV: 200 mV TIME/DIV: 500 nS

IC1 CN1 IC2

TP (RF. GND)

level: 1.0 � 1.5 Vp-p

TP (RF) CN3

� 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
RV1 FOCUS BIAS ADJ

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