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22
HCD-RG444
RFDC signal waveform
Checking Location: BD81A board (Side B)
CD SECTION
Note:
1. Use YEDS-18 disc (3-702-101-01) unless otherwise indicated.
2. Use an oscilloscope with more than 10M
Ω
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.
Note:
Note:
Note:
Connect an oscilloscope to test point (RFDCO) and TP (VC)
on the BD81A board.
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.
A clear RFDC signal waveform means that the shape “
◊
” can be
clearly distinguished at the center of the waveform.
VOLT/DIV: 200 mV
TIME/DIV: 500 ns
level: 0.6
±
0.15 Vp-p
RFAC Level Check
Connection:
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.
A clear RFAC signal waveform means that the shape “
◊
” can be
clearly distinguished at the center of the waveform.
RFAC signal waveform
Checking Location: BD81A board (Side B)
+
–
BD81A board
TP (RFACO)
TP (VC)
oscilloscope
VOLT/DIV: 200 mV
TIME/DIV: 500 ns
level: 1.0
±
0.4 Vp-p
S-curve Check
Connection:
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 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
• 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)
+
–
BD81A board
TP (FEO)
TP (VC)
oscilloscope
A
B
symmetry
within 2
±
1 Vp-p
H
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