Sony CX-LDB30 Service Manual page 22

CX-LDB30/LDB50
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:
BD board
TP (FED)
TP (VC)
Procedure:
1. Connect an oscilloscope to test point TP (FEO) and TP (VC)
on the BD board.
2. While depressing the CD u button, insert an AC plug.
3. Put the disc (YEDS-18) in and press the x button 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
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: BD board (Conductor Side)
RFDC Level Check
Connection:
BD board
TP (RFDCO)
TP (VC)
Procedure:
1. Connect an oscilloscope to test point (RFDCO) and TP (VC)
on the BD 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.
Note: A clear RFDC signal waveform means that the shape "◊" can
be clearly distinguished at the center of the waveform.
22
oscilloscope
+
–
symmetry
A
within 2 ± 1 Vp-p
B
oscilloscope
+
–
RFDC signal waveform
Checking Location: BD board (Conductor Side)
RFAC Level Check
Connection:
BD board
TP (RFACO)
TP (VC)
Procedure:
1. Connect an oscilloscope to test point TP (RFACO) and TP
(VC) on the BD 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.
RFAC signal waveform
Checking Location: BD board (Conductor Side)
VOLT/DIV: 200 mV
TIME/DIV: 500 ns
level: 0.6 ± 0.15 Vp-p
oscilloscope
+
–
VOLT/DIV: 200 mV
TIME/DIV: 500 ns
level: 1.0 ± 0.4 Vp-p