Sony HCD-EC68P, Service Manual

Page: 22 / 66

HCD-EC68P/EC78P
22
SECTION 5
ELECTRICAL ADJUSTMENTS
CD SECTION
Note:
1. CD Block is basically constructed to operate without adjustment.
2. Use YEDS-18 disc (3-702-101-01) unless otherwise indicated.
3. Use an oscilloscope with more than 10 M
Ω
impedance.
4. Clean the object lens by an applicator with neutral detergent when the
signal level is low than speci fi ed value with the following checks.
5. Check the focus bias check when optical pick-up block is replaced.
FOCUS BIAS CHECK
+
–
CD board
oscilloscope
(DC range)
TP121 (RFI)
TP124 (VC)
Procedure :
1. Connect the oscilloscope to TP121 (RFI) and TP124 (VC) on
the CD board.
2. Press the [ I /
1
] button to turn the power ON, and press the [
Z
]
button to open the CD disc tray.
3. Set disc (YEDS-18) on the trey and press the [
CD N
] button
to playback.
4. Con fi rm that oscilloscope waveform is as shown in the fi gure
below. (eye pattern)
A good eye pattern means that the diamond shape (
◊
) in the
center of the waveform can be clearly distinguished.
VOLT/DIV: 200 mV
TIME/DIV: 500 ns
level:
1.2 ± 0.3 Vp-p
Checking Location:
TP124
(VC)
– CD Board (Conductor Side) –
TP121
(RFI)
IC101
[AM]
Setting:
FUNCTION: AM
AM RF signal
generator
30% amplitude
modulation by
400 Hz signal
Output level: 54 dBuV
60 cm
set
loop antenna A loop antenna B
+
–
level meter
32
Ω
JACK board
PHONES jack (J492)
MAIN board
ANTENNA
CN801 pin
[FM]
Setting:
FUNCTION: FM
FM RF signal
generator
75kHz frequency
deviation by 1K Hz
signal
Output level: as low as possible
(8dBuV)
+
–
level meter
set
32
Ω
0.01 F
JACK board
PHONES jack (J492)
MAIN board
ANTENNA
CN801 pin
MAIN board
ANTENNA
CN801 pin
digital voltmeter
100 k
Ω
MAIN board
IC801 pin
XL
(TUNER VT)
•
Repeat the procedures in each adjustment several times.
TUNER SECTION 0 dB = 1
μ
V