Yamaha TX-497 - FM Tuner Section Adjustments; Fine Discriminator Balance Adjustment; Fine Monaural Distortion Adjustment

8
TX-497
TX-497
TEST POINTS
<FM TUNER SECTION>
Adjustment item
Rough adjustment of
discriminator balance.
Rough adjustment of
monaural distortion.
Fine adjustment of
discriminator balance.
Fine adjustment of
monaural distortion.
Verification of
discriminator balance.
Adjustment of frontend
IFT.
Adjustment of stereo
distortion.
Step
1
2
3
4
5
6
7
Signal (ANT IN)
FM SG:
98.1 MHz 70 dBµ
Modulation : 100 %
Monaural : 1 kHz
Same as Step 1.
Same as Step 1.
Same as Step 1.
Same as Step 1.
FM SG:
98.1 MHz 30 dBµ
Modulation : 100 %
Monaural : 1 kHz
FM SG:
98.1 MHz 70 dBµ
Modulation : 100 %
Stereo L or R : 1 kHz
Adjusted
point
L8
(right side)
L8
(left side)
L8
(right side)
L8
(left side)
Frontend
IFT
VR1, VR2
Reception
frequency
Preset
A-4: 98.1 MHz
Same as Step 1.
Same as Step 1.
Same as Step 1.
Same as Step 1.
Same as Step 1.
Same as Step 1.
Rating
DC 0 V ±100mV
at tuning point.
Minimize distortion.
DC 0 V ±50mV
Minimize distortion.
(to less than 0.7%)
DC 0 V ±50mV
Adjust so that the
DC voltage is
maximum.
CAUTION:
If IFT core is turned
excessively, the
sensitivity reduces.
(Maximum ±90°)
Minimize distortion.
Tuning mode is
AUTO.
Test point
TP1, TP2
(both end
of R51)
OUTPUT
TP1, TP2
OUTPUT
TP1, TP2
TP3, GND
OUTPUT
LINEOUT AMANT GND FMANT
LR
L13 L12 VR4
VR3
R51
J6
J7
VR2
VR1
L10
L5
L8
PK2
PK1
J73
TP2
TP1
TP3
J108
GND
BALANCE
DISCRIMINATOR
DISTORTION
MONAURAL
FRONTEND
IFT
DISTORTION
STEREO
AMSENSITIVITY
SEPARATION
METER
SIGNAL