17
HCD-GX20
SECTION 4
ELECTRICAL ADJUSTMENTS
FM Tuned Level Adjustment
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
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
FM RF Signal generator
75
Ω
coaxial
Carrier frequency : 98 MHz
Modulation : AUDIO 1 kHz, 75 kHz
deviation (100%)
Output level : 30 dB (at 75
Ω
open)
FM ANTENNA terminal
(JK103)
set
FM RF Signal generator
75
Ω
coaxial
Carrier frequency : 98 MHz
Modulation : AUDIO 1 kHz, 75 kHz
deviation (100%)
Output level : 60 dB (at 75
Ω
open)
FM ANTENNA terminal
(JK103)
set
RV101:
FM TUNED LEVEL
AM RF Signal generator
30% amplitude
modulation by
400Hz signal
output level : as low as possible
AM ANTENNA terminal
(JK103)
set
AM IF Adjustment
TUNER SECTION
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
maximum.
headphones jack (JK691)
level meter
set
16
Ω
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