Service manual

38
CD SECTION
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 10 MΩ 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 an oscilloscope to TP (FE) and TP (VC).
2. Connect between TP (FE1) and TP (GND) by lead wire.
3. Connect between TP (AGCCON) and TP (GND) by lead wire.
4. Press the I/1 button to turn the power on.
5. Load a disc (YEDS-18) and press the H S (CD) button to
actuate the focus search. (In consequence of open and close the
disc tray, actuate the focus search)
6. Confirm that the oscilloscope waveform (S-curve) is
symmetrical between A and B. And confirm peak to peak level
within 4 ±1 Vp-p.
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 an oscilloscope to TP (RF) and TP (VC).
2. Connect between TP (AGCCON) and TP (GND) by lead wire.
3. Press the I/1 button to turn the power on.
4. Load a disc (YEDS-18) and playback the number five track.
5. Confirm that the oscilloscope waveform is clear and check RF
signal level is correct or not.
6. After check, remove the lead wire connected in step 2.
BD (CD) board
TP(FE)
TP(VC)
+
–
oscilloscope
symmetry
S-curve waveform
within 4
± 1 Vp-p
A
B
BD (CD) board
TP(RF)
TP(VC)
+
–
oscilloscope
Note: 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
Procedure:
1. Connect an oscilloscope to TP (TE) and TP (VC) board.
2. Press the I/1 button to turn the power on.
3. Load a disc (YEDS-18) and playback the number five track.
4. Press the H S (CD) button. (Becomes the 1 track jump
mode.)
5. Confirm that the level B and A (DC voltage) on the oscilloscope
waveform.
1 track jump waveform
Specification level: × 100=less than ±22%
6. After check, remove the lead wire connected in step 1.
Adjustment Location:
VOLT/DIV : 200 mV
TIME/DIV : 500 ns
level : 1.45 ± 0.3 Vp-p
BD (CD) board
TP(TE)
TP(VC)
+
–
oscilloscope
0V
Center of
waveform
B
Symmetry
A (DC voltage)
level=1.3
± 0.6 Vp-p
A
B
TP (VC)
TP (RF)
TP
(AGCCON)
TP (FE)
TP (FE1)
TP
(TE)
– BD (CD) BOARD (Conductor Side) –