22
HCD-GN800
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 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.
S-curve Check
Connection:
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.)
– MAIN BOARD (Component Side) –
REC LEVEL
ADJUSTMENT
REC BIAS ADJUSTMENT
CN301
IC301
3
1
(R-CH)
(R-CH)
(L-CH)
(L-CH)
RV301
RV351
RV304
RV354
+
–
CD board
TP4 (FE)
TP7 (DVC)
oscilloscope
A
B
symmetry
within 2.4
±
1 Vp-p
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
MD (VIDEO)
button to select VIDEO. (This step is not
necessary if the above test mode has already been set)
2. Insert a tape into deck B.
3. After press
[REC PAUSE/START]
button, press
[REC PAUSE/
START]
button, then recording start.
4. Mode: Record
5. Mode: Playback
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
set
MAIN board
MD/VIDEO (AUDIO) IN (J117)
315 Hz, 50 mV (–23.8 dB)
blank tape
CS-123
600
Ω
attenuator
AF OSC
+
–
set
recorded
portion
MAIN board
CN301 Pin
2
(GND)
MAIN board
CN301
Pin
1
(L-CH)
Pin
3
(R-CH)
level meter
