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SECTION 5
ELECTRICAL BLOCK CHECKING
Note:
1. CD Block is basically designed to operate without adjustment.
Therefore, 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
Procedure :
1. Connect oscilloscope to test point TP (FE) on BD board.
2. Connect between test point TP (FEI) and TP (VC) 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. 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
Procedure :
1. Connect oscilloscope to test point TP (RF) 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.
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)
Procedure :
1. Connect oscilloscpe to test point TP (TE) on BD board.
2. Turned Power switch on.
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%
1 track jump waveform
E-F Balance Check (With remote commander)
Procedure :
1. Connect the test point TP1 (ADJ : JW75) on MAIN board to the
ground with a lead wire on main board.
2. Connect oscilloscpe to test point TP (TE) on BD board.
3. Turn the Power switch on to set the ADJ mode.
4. Put disc (YEDS-18) in to play the number five track.
5. Press the “3” button. (The tracking servo and the sledding servo
are turned OFF.)
oscilloscope
BD board
TP (FE)
TP (VC)
symmetry
A
B
within 3 ± 1 Vp-p
BD board
TP (RF)
TP (VC)
oscilloscope
level : 1.3 Vp-p
VOLT/DIV : 200mV
TIME/DIV : 500ns
+0.25
–0.20
oscilloscope
BD board
TP (TE)
TP (VC)
Center of the waveform
0V
B
level : 1.3 ± 0.6 Vp-p
symmetry
A (DC voltage)
oscilloscope
BD board
TP (TE)
TP (VC)
