Sony CDX-3170, Руководство по обслуживанию

Страница: 14 / 44

– 14 –
SECTION 3
ELECTRICAL ADJUSTMENTS
TUNER SECTION
Cautions during repair
When the tuner unit is defective, replace it by a new one be-
cause its internal block is difficult to repair.
0 dB = 1
µ
V
FM VT Voltage Adjustment
Setting :
SOURCE button : FMI
FM Center Adjustment
Setting :
SOURCE button : FMI
Procedure :
Adjust for following value reading on digital voltmeter.
Frequency Display 87.5 MHz 107.9 MHz
Reading on Digital voltmeter 1.42
±
0.05 V 7.2
±
0.5 V
Adjustment Part T4 (confirmation)
Adjustment Location : See page 17.
Procedure :
1. Adjust T5 on TU1 so that the reading on the digital voltmeter
becomes in 0
±
50 mV.
2. Output an Fcenter 10 dB signal output from FM RF signal
generator so that the LINE OUT REAR jack is –20 dBs.
3. Change the FM RF signal generator frequency and check the
deviation of the frequency on + side and – side when the LINE
OUT REAR jack drops 3 dB. (Both + side and – side is approx.
50 kHz.)
4. Re-adjust T5 on TU1 when the difference deviation of the
frequency does more than 10 kHz.
Adjustment Location : See page 17.
Carrier frequency : 97.9 MHz
Output level
: 60 dB (1 mV)
Mode : mono
Modulation : 1 kHz, 75 kHz deviation (100 %)
FM RF signal
generator
dummy
antenna antenna
terminal
set
50 Ω
50 Ω
digital
voltmeter
FM VT OUT +
–
FM RF signal
generator
dummy
antenna
antenna
terminal
set
50 Ω
50
Ω
digital
voltmeter
+
–
FM CENTER
OUT
(Both side or R32.)
IC2 pin
!‹
IC2 pin
!‡
0 dBs
–3 dBs
(fc–10) fc (fc+10) (kHz)