Electrical Adjustment/Practical Service Figure - Aiwa XR-M88 Service Manual

ELECTRICAL ADJUSTMENT
1 2
L772
L771
IC771
30
TP2
TP3
TP4
R785
TUNER C.B
TP1
FFE801
5
L981
GND
TP6 TP5
CN701
12 11 10
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< TUNER SECTION >
1. DC Balance/Mono Distortion Adjustment
Settings: • Test point: TP3, TP4
• Adjustment location: L771
• Input level: 54dB
Method: Set to FM 98.0MHz and adjust L771 so that
the voltage between TP3 and TP4 becomes
0V±0.04V.
Next, check that the distortion is less than
1.3%.
2. AM IF Adjustment
Settings: • Test point: TP5, TP6
L772 .............................................. 450kHz
3
3. AM Tracking Adjustment
Settings: • Test point: TP5, TP6
• Adjustment location: L981
Method: Set to AM 999kHz and adjust L981 so that the
test point becomes maximum.
4. AM VT Check
Settings: • Test point: TP1 (VT)
Method: Set to AM 1710kHz and check that the test
point is less than 7.0V.
Then set to AM 530kHz and check that the test
point is more than 0.5V.
5. Clock Frequency Check
Settings: • Test point: TP2 (CLK IC771 pin30)
Method: Set to AM 1710kHz and check that the test
point becomes 2160kHz±45Hz.
6. FM VT Check
Settings: • Test point: TP1 (VT)
Method: Set to FM 87.5MHz, 108.0MHz and check that
the test point is more than 0.5V (87.5MHz) and
less than 8.0V (108.0MHz).
PRACTICAL SERVICE FIGURE
< TUNER SECTION >
<FM SECTION>
IHF Sensitiviy: 4dB±6dB
(THD 3%) (at 87.5/98.0MHz)
5dB±6dB (at 108MHz)
Signal to noise ratio: More than 65dB
(at 98.0MHz)
Distortion: Less than 1.3%
(Input: 66dB) (at 98.0MHz)
Stereo separation: More than 25dB
(at 98.0MHz)
Intermediate frequency: 10.7MHz
<AM SECTION>
Sensitivity: 54dB±6dB (at 600kHz)
(S/N 20dB) 52dB±6dB
(at 1000/1400kHz)
Signal to noise ratio: 41dB±36dB (at 1000kHz)
(Input: 100dB)
Distortion: Less than 2.0%
(at 1000kHz)
Intermediate frequency: 450kHz
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