– 14 –
SECTION 4
ELECTRICAL ADJUSTMENTS
+
–
BD board
TP (TEO)
TP (VC)
oscilloscope
(DC range)
+
–
BD board
TP (RF)
TP (VC)
oscilloscope
5. Confirm that the oscilloscope waveform (S-curve) is symmetri-
cal between A and B. And confirm peak to peak level within
2.4 ± 0.7 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. (stop mode)
3. Put disc (YEDS-18) in and press the
^
button.
4. Confirm that oscilloscope waveform is clear and check RF sig-
nal level is correct or not.
Note: Clear RF signal waveform means that the shape “
≈
” can
be clearly distinguished at the center of the waveform.
RF signal waveform
E-F Balance (Traverse) Check
Connection:
Procedure:
1. Connect the TP501 (ADJ) and Ground with lead wire. (on the
display board)
2. Connect the oscilloscope to TP (TEO) and TP (VC) on BD
board.
3. Turned power switch on.
4. Put disc (YEDS-18) in and press the
^
button.
5. Press the TIME button. (Tracking servo and sled servo are
turned off.)
6. Confirm that the oscilloscope waveform is symmetrical on the
top and bottom in relation to 0 Vdc, and check this level.
A
B
symmetry
within 2.4 ± 0.7 Vp-p
VOLT/DIV: 200 mV
TIME/DIV: 500 ns
(with the 10 : 1 probe
in use)
level: 1.3 ± 0.3 Vp-p
Notes:
1. CD Block basically constructed to operated without adjust-
ment.
Therefore, check eaech 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 fol-
lowing checks.
5. Adjust the focus bias adjustment when optical pick-up is re-
placed.
Focus Bias Adjustment
This adjustment is to be done when the optical pick-up is replaced.
Condition: This adjustment is performed with the set placed hori-
zontally.
Connection:
+
–
BD board
TP (FEO)
TP (VC)
oscilloscope
Procedure:
1. Connect the oscilloscope to TP (FEO) and TP (VC) on BD
board.
2. Connect the TP (FOK) and TP (GND) with 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.)
VOLT/DIV: 200 mV
TIME/DIV: 500 ns
(with the 10 : 1 probe
in use)
1.3 ± 0.3 Vp-p
Adjustment Procedure:
1. Connect the oscilloscope to TP (RF) and TP (VC) on BD board.
2. Turned power switch on. (stop mode)
3. Put disc (YEDS-18) in and press the
^
button.
4. Adjust RV101 so that the oscilloscope waveform is as shown
in the figure below (eye pattern).
A good eye pattern means that the diamond shape (
≈
) in the
center of the waveform can be clearly distinguished.
5. After adjustment, check the RF signal level.
•
RF signal reference waveform (eye pattern)
When observing the eye pattern, set the oscilloscope for AC
range and raise vertical sensitivity.
S-Curve Check
Connection:
+
–
BD board
TP (RF)
TP (VC)
oscilloscope
(AC range)
