Sony HCD-J3MD Service Manual page 42

CD SECTION
Note:
1. CD Block is basically constructed 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 (CD) board
TP (FE)
TP (VC)
Procedure :
1. Connect the oscilloscope to test points TP (FE) and TP (VC).
2. Connect TP (FEI) and Ground, and TP (AGCCON) and Ground
of the BD board with lead wires.
3. Press the ?/1 button to turn the set ON.
4. With the disc (YEDS-18) loaded, press the CD 7 button and
perform focus search. (Focus search will be performed in the
same way even while the disc table is pushed in and out.)
5. Check the symmetry and peak to peak level of the oscilloscope
waveform (S curve) at this time.
S-curve waveform
6. After check, remove the lead wire connected in step 2.
Note: • Try to measure several times to make sure that the ratio of
A : B or B : A is more than 10 : 7.
• Take sweep time as long as possible and light up the bright-
ness to obtain best waveform.
Checking Location : BD (CD) board
RF Level Check
BD (CD) board
TP (RF)
TP (VC)
Procedure :
1. Connect oscilloscope to test point TP (RF) and TP (VC) on BD
board.
2. Connect TP (AGCCON) and Ground of the BD (CD) board with
lead wires.
3. Press the ?/1 button to turn the set ON.
4. Put disc (YEDS-18) in and playback 5th track.
5. Confirm that oscilloscope waveform is clear and check RF signal
level is correct or not.
6. After check, remove the lead wire connected in step 2.
42
oscilloscope
+
–
symmetry
A
Within 4 ± 1 Vp-p
B
oscilloscope
+
–
6. After check, remove the lead wire connected in step 2.
Note: Clear RF signal waveform means that the shape "◊" can be
clearly distinguished at the center of the waveform.
Checking Location : BD (CD) board
E-F Balance (1 Track Jump) check
BD (CD) board
TP (TE)
TP (VC)
Procedure:
1. Connect oscilloscope to test point TP (TE) and TP (VC) on BD
board.
2. Press the ?/1 button to turn the unit ON.
3. Put disc (YEDS-18) in to play the number five track.
4. Press the CD 7 button.
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 = ± 22 (%) or less
• B = 1.3 ± 0.6 Vp-p
1 track jump waveform
0V
level : 1.3 ± 0.6 Vp-p
Checking Location : BD (CD) board
[ BD (CD) BOARD ] — SIDE B —
TP
(VC)
IC103
TP
(RF)
TP
(AGCCON)
TP (FE)
TP
TP
(TE)
(FEI)
VOLT/DIV : 200mV
TIME/DIV : 500ns
level : 1.45 ± 0.3 Vp-p
oscilloscope
+
–
Center of the waveform
B
A (DC voitage)
Symmetry