Electrical Adjustments - Sony HCD-GX20 Service Manual

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TUNER SECTION
FM Tuned Level Adjustment
FM RF Signal generator
Carrier frequency : 98 MHz
Modulation : AUDIO 1 kHz, 75 kHz
deviation (100%)
: 30 dB (at 75 Ω open)
Output level
Procedure:
1. Supply a 98 MHz signal at 28 dB from the ANTENNA terminal.
2. Tune the set to 98 MHz.
3. Adjust RV101 to the point (moment) when the TUNED
indicator will change from going off to going on.
Adjustment Location: MAIN board
Null Adjustment
FM RF Signal generator
Carrier frequency : 98 MHz
Modulation : AUDIO 1 kHz, 75 kHz
TE
L 13942296513
deviation (100%)
: 60 dB (at 75 Ω open)
Output level
Procedure:
1. Supply a 98 MHz signal at 60 dB from the ANTENNA terminal.
2. Tune the set to 98 MHz.
3. Measure voltage between pin 21 and pin 23 of IC 101. Adjust
T101 until the voltage becomes 0 V.
Adjustment Location: MAIN board
[MAIN BOARD] Component side
T101: NULL
IFT101: AM IF
RV101:
FM TUNED LEVEL
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ELECTRICAL ADJUSTMENTS

75 Ω coaxial
set
FM ANTENNA terminal
(JK103)
75 Ω coaxial
set
FM ANTENNA terminal
(JK103)
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SECTION 4
2 9
8
AM IF Adjustment
AM RF Signal generator
30% amplitude
modulation by
400Hz signal
output level : as low as possible
set
Procedure:
1. Set the frequency of the AM RF signal generator to 1000 kHz
(at 10 kHz step) or 999 kHz (at 9 kHz step).
2. Tune the set to AM 1000 kHz (at 10 kHz step) or 999 kHz (at 9
kHz step).
3. Adjust IFT101 so that the reading on level meter becomes in
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3 6 7 1 3 1 5
maximum.
co
.
HCD-GX20
9 4 2 8
set
AM ANTENNA terminal
(JK103)
level meter
16 Ω
headphones jack (JK691)
0 5 8 2 9 9 4 2 8
m
9 9
9 9
17