– 12 –
SECTION 5
ELECTRICAL BLOCK CHECKING
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.
S Curve Check
Connection:
Procedure :
1. Connect oscilloscope to test point TP2 (FE) on BD board.
2. Connect between test point TP3 (FEI) and TP (VC) by lead wire.
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±1
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 TP1 (RF) on BD 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.
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 (1 Track Jump) Check
(Without remote commander)
Connection:
Procedure :
1. Connect oscilloscpe to test point TP4 (TE) on BD board.
2. Turn ON the power.
3. Put disc (YEDS-18) in to play the number five track.
4. Press the “
P
(Pause)” button. (Becomes the 1 track jump mode)
5. 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%
E-F Balance Check (With remote commander)
Connection:
Procedure :
1. Connect the test point TP1 (ADJ : JW98) on MAIN board to the
ground with a lead wire on MAIN board.
2. Connect oscilloscpe to test point TP4 (TE) on BD 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 “4” button. (The tracking servo and the sledding servo
are turned OFF.)
A
B
symmetry
within 3
±
1 Vp-p
+
–
BD board
TP2 (FE)
TP (VC)
oscilloscope
+
–
BD board
TP1 (RF)
TP (VC)
oscilloscope
VOLT/DIV: 200 mV
TIME/DIV: 500 ns
level: 1.2
±
0.2 Vp-p
0 V
Center of the waveform
A (DC voltage)
B
symmetry
level: 1.3
±
0.6 Vp-p
1 track jump waveform
+
–
BD board
TP4 (TE)
TP (VC)
oscilloscope
(DC range)
+
–
BD board
TP4 (TE)
TP (VC)
oscilloscope
(DC range)
