Electrical Block Checking - Sony MCE-F88K Service Manual

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 10MΩ 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
BD board
TP (FE)
TP (VC)
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. Turn Power switch on.
4. Put disc (YEDS-18) in 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 4.5 ± 1
Vp-p.
S-curve waveform
6. 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
BD board
TP (RF)
TP (VC)
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
SECTION 5

ELECTRICAL BLOCK CHECKING

oscilloscope
symmetry
A
Within 4.5 ± 1 Vp-p
B
oscilloscope
VOLT/DIV : 200mV
TIME/DIV : 500ns
0.25
level : 1.3 ±
Vp-p
0.2
E-F Balance Check
BD board
TP (TE)
TP (VC)
Procedure :
1. Connect oscilloscpe to test point TP (TE) on BD board.
2. Short-circuit the SL502 of the VIDEO 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 PICTURE button. (The tracking servo and the sledding
servo are turned OFF.)
6. 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%
Traverse waveform
0V
7. Press the PICTURE button. (The tracking servo and sledding
servo are turned ON.) Confirm the C (DC voltage) is almost
equal to the A (DC voltage) is step 7.
Traverse waveform
0V
Tracking servo
Sledding servo
OFF
8. Desolder the shortland short-circuited at step 2.
Adjustment Location :
[BD BOARD] – SIDE A –
TP
(TE)
oscilloscope
Center of the waveform
B
A (DC voltage)
level : 1.3 ± 0.6 mVp-p
Tracking servo
Sledding servo
ON
TP TP
(RF) (VC)
TP
TP
(FE)
(FEI)
C (DC
voltage)
15