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SECTION 5
ELECTRICAL BLOCK CHECKING
oscilloscope
BD board
TP (FE)
TP (VC)
symmetry
A
B
Within 4.5
±
1 Vp-p
oscilloscope
BD board
TP (RF)
TP (VC)
VOLT/DIV : 200mV
TIME/DIV : 500ns
level : 1.2
±
0.2 Vp-p
oscilloscope
BD board
TP (TE)
TP (VC)
0V
level : 500 Vp-p
A (DC voltage)
Center of the waveform
B
symmetry
+ 0.7
– 0.6
oscilloscope
BD board
TP (TE)
TP (VC)
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. Connect both ends of TP R151 of the BD board to the lead wire.
4. Turn Power switch on.
5. Put disc (YEDS-18) in and actuate the focus search. (actuate the
focus search when disc table is moving in and out.)
6. Check the oscilloscope waveform (S-curve) is symmetrical
between A and B. And confirm peak to peak level within 4.5 ± 1
Vp-p.
S-curve waveform
7. After check, remove the lead wire connected in step 2 and 3.
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. Turn 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 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 general remote commander)
Procedure :
1. Connect oscilloscpe to test point TP (TE) on BD board.
2. Turn 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 general remote commander)
Procedure :
1. Connect the test point TP1 (ADJ) on MAIN board to the ground
with a lead wire.
2. Connect oscilloscpe to test point TP (TE) on BD board.
3. Set the COMMAND MODE switch to CD1.
4. Turn the Power switch on to set the ADJ mode.
5. Put disc (YEDS-18) in to play the number five track.
6. Press the
3
button. (The tracking servo and the sledding servo
are turned OFF.)
