Sony HCD-ED2 Service Manual page 12

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 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/u button to turn the set ON.
4. With the disc (YEDS-18) loaded, press the ( button and per-
form 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 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 bright-
ness to obtain best waveform.
Checking Location : BD board
RF Level Check
BD 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 board with lead
wires.
3. Press the 1/u button to turn the set ON.
4. Put disc (YEDS-18) in and playback 5track.
5. Confirm that oscilloscope waveform is clear and check RF sig-
nal level is correct or not.
6. After check, remove the lead wire connected in step 2.
12
oscilloscope
+
–
symmetry
A
Within 4 ± 1 Vp-p
B
oscilloscope
+
–
Note: Clear RF signal waveform means that the shape "◊" can be
clearly distinguished at the center of the waveform.
RF signal waveform
Checking Location : BD board
E-F Balance (1 Track Jump) check
BD board
TP (TE)
TP (VC)
Procedure:
1. Connect oscilloscope to test point TP (TE) and TP (VC) on BD
board.
2. Press the 1/u button to turn the unit ON.
3. Put disc (YEDS-18) in to play the number five track.
4. Press the ( 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 = less then ± 22 (%)
• B = 1.3 ± 0.6 Vp-p
1 track jump waveform
0V
level : 1.3 ± 0.6 Vp-p
Checking Location : BD board
Checking Location : BD board
[ BD BOARD ] — SIDE B —
TP
(VC)
IC102
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
IC101