Yamaha RX-V495 Service Manual page 24

RX-V495/RX-V495RDS/HTR-5140/HTR-5140RDS
FM Adjustment
1. Before Adjustment
For dBµ, 1µV=0dBµ applies.
Example : 60dBµ=1mV
100% modulation means that the frequency deviation is
±75kHz.
Install the Matching Transformer and connect FM SG.
2. Connection diagram (Measuring instruments)
Discriminator balance adjustment.
FM
FM ANT
FM
dummy
SG GND
antenna
Oscillator
Monaural distortion adjustment
FM
ANT
FM
FM
TUNER
dummy
SG
GND
antenna
Oscillator
See page 22 for TP locations & adjustment points.
Step Adjustment item
Rough adjustment of
discriminator balance
1
Rough adjustment of
2
monaural distortion
Fine adjustment of
3
discriminator balance
Fine adjustment of
4
monaural distortion
Verification of
5
discriminator balance
Execution of FACTORY PRESET (Refer to page 20) will facilitate setting reception frequency for adjustment.
23
TP1
TUNER
DCVM
P. C. B.
TP2
L
Oscilloscope
R
P. C. B.
REC
OUT
DIST. M
Reception
Signal (ANT IN)
frequency
FM ANT (75Ω) 98.1MHz
98.1MHz (A-4)
70dBµ
MONO 100Hz
100% modulation
Same as Step 1. 98.1MHz
(A-4)
Same as Step 1. 98.1MHz
(A-4)
Same as Step 1. 98.1MHz
(A-4)
Same as Step 1. 98.1MHz
(A-4)
Set each switch to the following position unless otherwise
specified.
INPUT SELECTOR ....... TUNER
TUNING MODE ............. AUTO
Stereo distortion adjustment/separation adjustment.
FM
ANT
FM
FM
dummy
SG
GND
antenna
SSG
Sensitivity Verfication
FM
ANT
FM
FM
dummy
SG
GND
antenna
Adjustment
Test point
point
T1 Both ends of R25
(Front side core) (Between TP1 and TP2)
T1 REC OUT L, R
(Antenna side core)
T1 Both ends of R25
(Front side core) (Between TP1 and TP2)
T1 REC OUT L, R
(Antenna side core)
T1 Both ends of R25
(Front side core) (Between TP1 and TP2)
L
Oscilloscope
TUNER
R
YLF-15
P. C. B.
REC
(LPF)
ACVM
OUT
DIST. M
L
Oscilloscope
TUNER R
P. C. B.
REC
ACVM
OUT
DIST. M
Rating
DC 0V±100mV
Minimize the distortion.
DC 0V±50mV
Minimize the distortion
(0.9%/–41dB or less).
DC 0V±50mV