Sony HCD-H991AV, Service Manual

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CD SECTION
Note:
1. CD Block is basically designed 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
BD board
TP (RF)
TP (VC)
oscilloscope
Procedure:
1. Connect oscilloscope to test point TP (RF). (Ground terminal : TP
(VC))
2. Turned Power switch on.
3. Put disc (YEDS-18) in and playback.
4. Adjust RV101 so that the waveform is clear.
(Clear RF signal waveform means that the shape “ ” can be clearly
distinguished at the center of the waveform.)
5. After adjustment, check the RF signal level.
• RF signal
VOLT/DIV: 200 mV
TIME/DIV: 500 nS
level: 1.3
±
0.3 Vp-p
Procedure :
1. Connect oscilloscope to test point TP (FEO).
2. Connect between test point TP (FOK) and Ground by lead wire.
3. Turn Power switch on.
4. Put disc (YEDS-18) in and turned Power switch on again and
actuate the focus search. (actuate the focus search when disc table
is moving in and out.)
5. Check the oscilloscope waveform (S-curve) is symmetrical
between A and B. And confirm peak to peak level within 2.4
±
0.7
Vp-p.
S-curve waveform
S Curve Check
6. After check, remove the lead wire connected in step 2.
Note:
• Try to measure several times to make sure than the ratio of
A : B or B : A is more than 10 : 7.
• Take sweep time as long as possible and light up the
brightness to obtain best waveform.
RF Level Check
Procedure :
1. Connect oscilloscope to test point TP (RF) on BD 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.
RF signal waveform
level: 1.3
±
0.3 Vp-p
VOLT/DIV: 200 mV
TIME/DIV: 500 nS
BD board
TP (FE)
TP (VC)
oscilloscope
A
B
within 2.4
±
0.7 Vp-p
symmetry
BD board
TP (RF)
TP (VC)
oscilloscope
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