– 20 –
CD SECTION
Note:
1.
CD Block is basically designed to operate without adjustment. There-
fore, 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 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.
Focus Bias check
Procedure:
1. Connect oscilloscope to test point TP (RF). (GND terminal:
VC)
2. Turned Power switch on.
3. Put disc (YEDS-18) in and playback.
4. Confirm that the shape “
≈
” can be clearly distinguished at the
center of the waveform and check the RF signal level.
• RF signal
BD board
TP (FEO)
TP (VC)
+
–
oscilloscope
S Curve Check
Procedure:
1. Connect oscilloscope to test point TP (FEO).
2. Connect between test point TP (FOK) and GND 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
3 ± 1 Vp-p.
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 (TEO) on BD board.
2. Turned Power switch on.
3. Put disc (YEDS-18) in to play the number five track.
4. Confirm that oscilloscope waveform is clear and check RF
signal level is correct or not.
• SF signal
Note:
Clear RF 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:
1.3
±
0.3 Vp-p
BD board
TP (FEO)
TP (VC)
+
–
oscilloscope
S-curve waveform
BD board
TP (RF)
TP (VC)
+
–
oscilloscope
A
B
symmetry
within 3
±
1 Vp-p
VOLT/DIV: 200 mV
TIME/DIV: 500 ns
level:
1.3
±
0.3 Vp-p
