HCD-GPX555/GPX888
16
CD SECTION
Note:
1. CD Block is basically constructed to operate without adjustment.
2. Use YEDS-18 disc (Part No. 3-702-101-01) unless otherwise indicat-
ed.
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
Procedure :
1. Connect the oscilloscope to JL317 (RF Signal) and JL312 (Vc/
Reference) on the MB board.
2. Press the [
?/1
STANDBY] button to turn the power on, and
press the [CD] button to select CD function.
3. Set disc (YEDS-18) and press the [
u
] 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.
Checking Location:
-MB Board (Conductor Side)-
+
–
MB board
oscilloscope
(DC range)
JL317 (RF Signal)
JL312 (Vc/Reference)
VOLT/DIV: 200 mV
TIME/DIV: 500 ns
level:
1.0 ± 0.25 Vp-p (CD)
SECTION 4
ELECTRICAL CHECK
FM AUTO STOP CHECK
Procedure:
1. Turn the power on.
2. Input the following signal from Signal Generator to FM an-
tenna input directly.
Carrier frequency : A = 87.5 MHz, B = 98 MHz, C = 108 MHz
Deviation
: 75 kHz
Modulation
: 1 kHz
ANT input
: 35 dBu (EMF)
Note:
Please use 75 ohm “coaxial cable” to connect SG and the
set. You cannot use video cable for checking.
Please use SG whose output impedance is 75 ohm.
3. Set to FM tuner function and scan the input FM signal with
automatic
scanning.
4. Con
fi
rm that input Frequency of A, B and C detected and
automatic scanning stops.
The stop of automatic scanning means “The station signal is
received in good condition”.
TUNER SECTION
0 dB = 1
μ
V
signal
generator
set
+
–
75
JL317
JL312
