HCD-G2500, HCD-XB20, HCD-XB22, LBT-G2500, LBT-XB20, LBT-XB22 - Sony Audio Service Manual (repair manual). Page 15

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— 15 —
CD SECTION
Note:
1.
CD Block is 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 an oscilloscope with more than 10M
Ω
 impedance.
4.
Clean the object lens by an applicator with neutral detergent
when the signal level is low than specified value with the
following checks.
5.
Adjust the focus bias adjustment when optical block is replaced.
Focus Bias Adjustment
RF Level Check

Procedure :
1.
Connect oscilloscope to test point TP01 on CD DECODER
board.
2.
Turned Power switch on.
3.
Put disc (YEDS-18) in and playback.
4.
Confirm that oscilloscope waveform is clear and check RF
signal level is correct or not.

Note: Clear RF signal waveform means that the shape “
◊
” can be
clearly distinguished at the center of the waveform.
oscilloscope
level: 1.0         Vp-p
VOLT/DIV: 200 mV
TIME/DIV: 500 nS
+0.3
–0.2

Adjustment Location: CD DECODER board

Procedure:
1.
Connect DC voltmeter to test point TP02 on CD DECODER
board.
2.
Turned Power switch on.
3.
Put disc (YEDS-18) in and stop.
4.
Adjust VR01 so that the DC voltmeter reading is 0 ± 20 mV.

Adjustment Location: CD DECODER board
Focus Gain Adjustment (VR02)
This gain has a margin, so even if it is slightly off.
There is no problem.
Therefore, do not perform this adjustment.
Please note that it should be fixed to mechanical center position
when you moved and do not know original position.
Adjustment Location
[CD DECODER BOARD] — Component side —
CD DECODER
board
TP02
FEO
VC
DC voltmeter
+
–
CD DECODER
board
RF
VC
TP01
VR01
(Focus Bias)
VR02
(Focus Gain)
IC01
TP01
TP02

Display

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