Read Sony HCD-DR8AV / HCD-W900AV Service Manual online
— 18 —
CD SECTION
Note:
1.
CD Block is basically constructed to operate without
adjustment. Therefore, check each item in order given.
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.
when the signal level is low than specified value with the
following checks.
S Curve Check
Procedure :
1.
1.
Connect the oscilloscope to test points TP (FE) and TP (VC).
2.
Connect TP (FEI) and GND, and TP (AGCCON) and GND of
the BD board with lead wires.
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
·P button and
perform focus search. (Focus search will be performed in the
same way even while the disc table is pushed in and out.)
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.
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.
RF Level Check
Procedure :
1.
1.
Connect oscilloscope to test point TP (RF) and TP (VC) on
BD board.
BD board.
2.
Connect TP (AGCCON) and GND of the BD board with lead
wires.
wires.
3.
Press the
1/u button to turn the set ON.
4.
Put disc (YEDS-18) in and playback 5 track.
5.
Confirm that oscilloscope waveform is clear and check RF
signal level is correct or not.
signal level is correct or not.
6.
After check, remove the lead wire connected in step 2.
Adjustment Location :
[ BD BOARD ] — SIDE A —
Procedure:
1.
1.
Connect oscilloscope to test point TP (TE) 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
·P 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:
(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
• B = 1.3 ± 0.6 Vp-p
1 track jump waveform
E-F Balance (1 Track Jump) check
oscilloscope
BD board
TP (FE)
TP (VC)
TP (VC)
+
–
–
symmetry
A
B
Within 4
±
1 Vp-p
oscilloscope
BD board
TP (RF)
TP (VC)
TP (VC)
+
–
–
VOLT/DIV : 200mV
TIME/DIV : 500ns
TIME/DIV : 500ns
level : 1.45
±
0.25 Vp-p
0V
Center of the waveform
B
Symmetry
A (DC voitage)
level : 1.3
±
0.6 Vp-p
oscilloscope
BD board
TP (TE)
TP (VC)
TP (VC)
+
–
–
TP
(VC)
(VC)
TP
(RF)
(RF)
TP
(TE)
(TE)
TP
(FE1)
(FE1)
TP (FE)
TP
(AGCCON)
(AGCCON)
Note:
Clear RF signal waveform means that the shape “
◊
” can be
clearly distinguished at the center of the waveform.
RF signal waveform
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