Sony CX-LFA660 Service Manual page 18

CX-LFA660/LFA770
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CD SECTION
Note:
1. Use YEDS-18 disc (3-702-101-01) unless otherwise indicated.
2. Use an oscilloscope with more than 10MΩ impedance.
3. Clean the object lens by an applicator with neutral detergent when the
signal level is low than specified value with the following checks.
S-curve Check
Connection:
BD81A board
TP (FEO)
TP (VC)
Procedure:
1. Connect an oscilloscope to test point TP (FEO) and TP (VC)
on the BD81A board.
2. Turn the power on.
3. Put the disc (YEDS-18) in and press the
and actuate the focus search. (actuate the focus search when
disc table is moving in and out)
4. Check the oscilloscope waveform (S-curve) is symmetrical
between A and B. And confirm peak to peak level within 2 ± 1
Vp-p.
S-curve waveform
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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.
Checking Location: BD81A board (Side B)
RFDC Le vel Check
Connection:
BD81A board
TP (RFDCO)
TP (VC)
Procedure:
1. Connect an oscilloscope to test point (RFDCO) and TP (VC)
on the BD81A board.
2. Turn the power on.
3. Put the disc (YEDS-18) in to playback the number five track.
4. Confirm that oscilloscope waveform is clear and check RFDC
signal level is correct or not.
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Note:
A clear RFDC signal waveform means that the shape "◊" can be
clearly distinguished at the center of the waveform.
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oscilloscope
+
–
CD button
NX
symmetry
A
within 2 ± 1 Vp-p
B
oscilloscope
+
–
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RFDC signal waveform
Checking Location: BD81A board (Side B)
RFAC Level Check
Connection:
BD81A board
TP (RFACO)
TP (VC)
Procedure:
1. Connect an oscilloscope to test point TP (RFACO) and TP
(VC) on the BD81A board.
2. Turn the power on.
3. Put the disc (YEDS-18) in to playback the number five track.
4. Confirm that oscilloscope waveform is clear and check RFAC
signal level is correct or not.
Note:
A clear RFAC signal waveform means that the shape "◊" can be
clearly distinguished at the center of the waveform.
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RFAC signal waveform
Checking Location: BD81A board (Side B)
co
.
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VOLT/DIV: 200 mV
TIME/DIV: 500 ns
level: 0.6 ± 0.15 Vp-p
oscilloscope
+
–
0 5 8 2 9 9 4 2 8
VOLT/DIV: 200 mV
TIME/DIV: 500 ns
level: 1.0 ± 0.4 Vp-p
m
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