Cd Section - Sony HCD-GN700 Service Manual

HCD-GN700/GX8800
REC LEVEL ADJUSTMENT DECK B
Procedure:
In the MC test mode, the "REC memory mode" is convenient for
this adjustment. In the "REC memory mode" , when the REC starts
the input signal FUNCTION is switched to VIDEO automatically.
When the REC stops, the tape returns near to the recording start
position.
1. Press button to select VIDEO. (This step is not
MD (VIDEO)
necessary if the above test mode has already been set)
2. Insert a tape into deck B.
[REC PAUSE/START]
3. After press
START]
button, then recording start.
4. Mode: Record
MAIN board
MD/VIDEO (AUDIO) IN (J117)
315 Hz, 50 mV (–23.8 dB)
AF OSC
600 Ω
attenuator
5. Mode: Playback
MAIN board
CN301
recorded
Pin 1 (L-CH)
portion
Pin 3 (R-CH)
set
MAIN board
CN301 Pin 2 (GND)
6. Confirm the play back signal recorded in step 3 becomes
adjustable level as follows.
If these levels are not adjustable level, adjust the RV301 (L-
CH) and RV351 (R-CH) on the MAIN board to repeat steps 4
and 5.
Adjustable level:
CN301 PB level: 47.2 to 53.0 mV (–24.3 to –23.3 dB)
Adjustment Location: MAIN board
– MAIN BOARD (Component Side) –
22
[REC PAUSE/
button, press
blank tape
CS-123
set
level meter
+
–
REC LEVEL
ADJUSTMENT
3 1
RV301
CN301
(L-CH)
(R-CH)
RV351
IC301
RV304
RV354
(L-CH) (R-CH)
REC BIAS ADJUSTMENT

CD SECTION

Note:
1. CD Block is basically designed to operate without adjustment. There-
fore, 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
Connection:
CD board
TP4 (FE)
TP7 (DVC)
Procedure:
1. Connect an oscilloscope to test point TP4 (FE) and TP 7(DVC)
on the CD board.
2. Turn the power on.
3. Put the disc (YEDS-18) in and turned power switch on again
and actuate the focus search. (actuate the focus search when
disc table is moving in and out)
4. Check the oscilloscope waveform (S-curve) is symmetrical
between A and B. And confirm peak to peak level within 2.4 ± 1 Vp-p.
S-curve waveform
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.
Checking Location: CD board (SIDE B)
(See page 24.)
oscilloscope
+
–
symmetry
A
within 2.4 ± 1 Vp-p
B