11
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.
Procedure :
1.
Connect oscilloscope to test point TP (FE) on SERVO board.
2.
Connect between test point TP (FEI) and TP (VC) by lead wire.
3.
Turn
U
(power) switch on.
4.
Put disc (YEDS-18) in and turn
U
(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.
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.
Procedure :
1.
Connect oscilloscope to test point TP (RF) on SERVO board.
2.
Turn
U
(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.
Procedure :
1.
Connect oscilloscope to test point TP (TE) on SERVO board.
2.
Turn
U
(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 oscilloscope's waveform and the A
(DC voltage) of the center of the Traverse waveform.
Confirm the following :
A/B x 100 = less than ± 22%
Procedure :
1.
Connect oscilloscope to test point TP (TE) on SERVO board.
2.
Connect the test point TP21 (ADJ) on MAIN board to the
ground with a lead wire.
3.
Turn the
U
(power) switch on 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.)
S-curve waveform
symmetry
A
B
within 3
±
1Vp-p
0V
level : 1.3
±
0.6 Vp-p
symmetry
A (DC voltage)
B
Center of the waveform
1track jump waveform
SERVO board
oscilloscope
TP(TE)
TP(VC)
E-F Balance (1 Track Jump) Check
(Without remote commander)
SERVO board
oscilloscope
TP(FE)
TP(VC)
S Curve Check
SERVO board
oscilloscope
TP(RF)
TP(VC)
RF Level Check
SERVO board
oscilloscope
TP(TE)
TP(VC)
E-F Balance (Traverse) Check
(With remote commander)
RF signal waveform
VOLT/DIV : 200mV
TIME/DIV : 500ns
level : 1.45
±
0.25
Vp-p
