39
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
Ω
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.
5. Level doesn’t change whichever with normal speed or with four times
speed.
S Curve Check
Connection:
Procedure :
1. Connect oscilloscope to test point TP (FE) and TP (VC) on BD
(CD) board.
2. Mount 0
Ω
resister or short at R147 on BD (CD) board.
3. Turn ON the power.
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 3.6 ±
0.5 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 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
Connection:
Procedure :
1. Connect oscilloscope to test point TP (RFO) and TP (VC) on
BD (CD) board.
2. Turn ON the power.
3. Put disc (YEDS-18) in to play the number five track.
4. Confirm that oscilloscope waveform is clear and check RF sig-
nal level is correct or not.
+
–
BD (CD) board
TP2 (FE)
TP (VC)
oscilloscope
A
B
symmetry
within 3.6
±
0.5 Vp-p
+
–
BD (CD) board
TP1 (RF)
TP (VC)
oscilloscope
Note:
A clear RF signal waveform means that the shape “
◊
” can be clearly
distinguished at the center of the waveform.
RF signal waveform
E-F Balance Check
Connection:
Procedure :
1. Connect the test point TP (ADJ) on MAIN board to the ground
with a lead wire on MAIN board.
2. Connect oscilloscpe to test point TP (TE) and TP (VC) on BD
(CD) board.
3. Turn ON the power to set the ADJ mode.
4. Put disc (YEDS-18) in to play the number five track.
5. Press the
[ AMS ]
(CD) knob to display “A> TRK ON”
at the CD test mode. (The tracking servo and the sledding servo
are turned OFF)
6. Check the level B of the oscilliscope's waveform and the A (DC
voltage) of the center of the Traverse waveform.
Confirm the following :
A/B x 100 = less than ± 22%
7. Press the
[ AMS ]
(CD) knob. (The tracking servo and
sledding servo are turned ON)
Confirm the C (DC voltage) is almost equal to the A (DC volt-
age) is step 6.
8. Disconnect the lead wire of TP (ADJ) connected in step 1.
VOLT/DIV: 200 mV
TIME/DIV: 500 ns
(normal speed)
level: 1.2
±
0.2 Vp-p
+
–
BD (CD) board
TP4 (TE)
TP (VC)
oscilloscope
(DC range)
l
L
0 V
Center of the waveform
A (DC voltage)
B
Traverse waveform
level: 1.3
±
0.6 Vp-p
l
L
0 V
C (DC
voltage)
Traverse waveform
Tracking servo
Sledding servo
ON
Tracking servo
Sledding servo
OFF