HCD-GX8000, HCD-RG77 - Sony Audio Service Manual (repair manual). Page 21

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21
HCD-GX8000/RG77
CD SECTION
Note:
1.
CD Block is basically designed to operate without adjustment. Therefore,
check each item in order given.
2.
Use LUV-P01 (4-999-032-01) unless otherwise indicated.
3.
Use an oscilloscope with more than 10M
 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 (FEO).
2. Connect between TP (FEI) and TP (DVC) ( 1.65 V) by lead
wire.
3. Turn the power ON.
4. Load a disc (LUV-P01) and actuate the focus search. (In
consequence of open and close the disc tray, actuate the focus
search)
5. Confirm that the oscilloscope waveform (S-curve) is
symmetrical between A and B. And confirm peak to peak level
within 2 
±
 0.5 Vp-p.
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
brightness to obtain best waveform.
RF  LEVEL  CHECK
Procedure :
1. Connect an oscilloscope CH1 to TP (RFDC) and CH2 to TP
(RFAC).
2. Turn the power ON.
3. Load a disc (LUV-P01) and playback.
4. Confirm that oscilloscope waveform is clear and check if RF
signal level is correct or not.
BD board
Oscilloscope
TP(FEO)
TP(DVC)
symmetry
S-curve waveform
within 2 
±
0.5Vp-p
A
B
TP(RFDC)
TP(RFAC)
BD board
oscilloscope
TP(DVC)
Note:
Clear RF signal waveform means that the shape “ 
 ” can be clearly
distinguished at the center of the waveform.
E-F BALANCE (1  TRACK  JUMP)  ADJUSTMENT
Procedure :
1. Connect an oscilloscope to TP (TEO) and TP (DVC).
2. Turn the power ON.
3. Load a disc (LUV-P01) and playback the number nine track.
4. Press the hH button. (Becomes the 1 track jump mode.)
5. Confirm that the level B and A (DC voltage) on the oscilloscope
waveform.
6. Adjust RV101 on the BD board so that the center of waveform
becomes the same voltage of DVC. (i.e.  A=0V)
Connecting and Adjustment Location: BD board
RF signal waveform
VOLT/DIV : 200mV
TIME/DIV : 500ns
level : 0.65 
±
0.15Vp-p (RFDC)
1.1 
±
0.4Vp-p (RFAC)
TP(TEO)
TP(DVC)
BD board
oscilloscope
level=1.0 
±
0.5Vp-p
symmetry
A (DC voltage)
center of
waveform
B
DVC
1 track jump waveform
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