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– 19 –
CD SECTION
Notes:
1. CD block basically constructed to operate without adjustment. There-
fore, check each item in order given.
2. Use YEDS-18 disc (Part No.: 3-702-101-01) unless otherwise indicated.
3. Use the oscilloscope with more than 10 M
Ω
impedance.
4. Clean an 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:
Procedure:
1. Connect the oscilloscope to TP (FE) and TP (VC) on BD board.
2. Connect between test point TP (FOK) and GND by lead wire.
3. Turned 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. Confirm that the oscilloscope waveform (S-curve) is symmetri-
cal between A and B. And confirm peak to peak level within
3.0 ± 1.0 Vp-p.
S-curve waveform
6. After check, remove the lead wire connected in step 2.
Note:
• Try to measure several times to make sure that 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
Connection:
Procedure:
1. Connect the oscilloscope to TP (RF) and TP (VC) on BD board.
2. Turned power switch on.
3. Put disc (YEDS-18) in and press the
fl
button.
4. Confirm that the 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.
within 3.0 ± 1.0 Vp-p
RF signal waveform
When observing the eye pattern, set the oscilloscope for AC range
and raise vertical sensitivity.
+
–
BD board
TP (FE)
TP (VC)
oscilloscope
A
B
symmetry
+
–
BD board
TP (RF)
TP (VC)
oscilloscope
(AC range)
VOLT/DIV: 200 mV
TIME/DIV: 500 ns
(with the 10: 1 probe
in use)
level: 1.3 Vp-p
+0.25
–0.20
E-F Balance (Traverse) check
Connection:
Procedure:
1. Short-circuit SL502 of the VIDEO board to GND.
2. Connect oscilloscope to test point TP (TE) on BD board.
3. Turned Power switch on. Press
[FUNCTION]
button to select
CD.
4. Put disc (YEDS-18) in to play the number five track.
5. Press the
[PLAY MODE]
button.
(The tracking servo and the sledding servo are turned OFF.)
6. Check the level B of the oscilloscope’s waveform and the A
(DC voltage) of the center of the Traverse waveform.
Confirm the following:
Traverse waveform
7. Press the
[PLAY MODE]
button. (The tracking servo and sled-
ding servo are turned ON.) Confirm the C (DC voltage) is al-
most equal to the A (DC voltage) is step 6.
Traverse waveform
8. Desolder the short-land (SL502) short-circuited at step 1.
A
×
100 = less than ± 22 (%)
B
level: 1.3 ± 0.6 Vp-p
+
–
BD board
TP (TE)
TP (VC)
oscilloscope
A (DC
voltage)
B
0 V
Center of the waveform
C (DC
voltage)
0 V
Tracking servo
Sled servo
OFF
Tracking servo
Sled servo
ON