Read Sony CMT-EH25 / CMT-EH26 / HCD-EH25 / HCD-EH26 Service Manual online
HCD-EH25/EH26
11
Adjustment Location:
FM TUNE LEVEL CHECK
Procedure:
1. Turn on the set.
2. Input the following signal from signal generator to FM antenna
1. Turn on the set.
2. Input the following signal from signal generator to FM antenna
input directly.
Carrier frequency : A = 87.5 MHz, B = 98 MHz, C = 108 MHz
Deviation
Deviation
: 75 kHz
Modulation
: 1 kHz
ANT input
: 35 dBu (EMF)
Note: Use 75 ohm coaxial cable to connect signal generator and the set.
You cannot use video cable for checking.
Use signal generator whose output impedance is 75 ohm.
3. Set to FM tuner function and tune A, B and C signals.
4. Confi rm “TUNED” is lit on the display for A, B and C signals.
4. Confi rm “TUNED” is lit on the display for A, B and C signals.
When the selected station signal is received in good condition,
“TUNED” is displayed.
“TUNED” is displayed.
signal
generator
set
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
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 specifi 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 oscilloscope to TP122 (RFEQO) and TP124 (VC) on
1. Connect oscilloscope to TP122 (RFEQO) and TP124 (VC) on
the CD board.
2. Press the [
?/1
] button to turn the power on.
3. Set the disc (YEDS-18) and press the [CD
u] button to play-
back.
4. Confi 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.
center of the waveform can be clearly distinguished.
Checking Location:
CD SECTION
+
–
–
CD board
TP122 (RFEQO)
TP124 (VC)
oscilloscope
(DC range)
VOLT/DIV: 200 mV
TIME/DIV: 500 ns
level:
1.2 ± 0.3 Vp-p
TP124
(VC)
– CD Board (Conductor Side) –
TP122
(RFEQO)
IC101
L851
AM Tracking
Adjustment
L805
FM VT
Voltage
Adjustment
L804
FM Tracking
Adjustment
L806
FM Detector
Adjustment
L852
AM VT
Voltage
Adjustment
– MAIN Board (Component Side) –
JW403
(TUNER OUT L-ch)
JW402
(TUNER OUT R-ch)
JW148
(GND)
JW821
(VT)
CNP802
JW805
(GND)
– MAIN Board (Conductor Side) –
3
1
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