Aiwa XR-M300 Service Manual page 24

ADJUSTMENT <TUNER>
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1. Clock Frequency Check
Settings : • Test point : TP2 (CLK)
Method : Set to MW 1602kHz and check that the test point
is 2052kHz ± 45Hz.
2. MW VT Check
Settings : • Test point : TP1 (VT)
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Method : Set to MW 1602kHz and check that the test point
is less than 8.0V. Then set to MW 531kHz and
check that the test point is more than 0.6V.
3. MW Tracking Adjustment
Settings : • Test point : TP8 (Lch), TP9 (Rch)
• Adjustment location : L981 (1/3)
Method : Set to MW 999kHz and adjust L981 (1/3) so that
the test point becomes maximum.
4. LW VT Adjustment
Settings : • Test point : TP1 (VT)
• Adjustment location : L942
Method : Set to LW 144kHz and adjust L942 so that the
test point becomes 1.3V ± 0.05V.
Then set to LW 290kHz and check that the test
point is less than 8.0V.
5. LW Tracking Adjustment
Settings : • Test point : TP8 (Lch), TP9 (Rch)
• Adjustment location :
L941 .................................................... 144kHz
TC942 .................................................. 290kHz
Method : Set up TC942 to center before adjustment.
The level at 144kHz is adjusted to maximum by
L941. Then the level at 290kHz is adjusted to
maximum by TC942.
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TP8 TP9
(GND) (RCH)
(LCH)
L981
L941 L942
TC942
FFE801
TP1(VT)
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TP3(DC) TP4(DC)
TP2(CLK)
IC771
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L771
L772
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6. AM IF Adjustment
Settings : • Test point : TP8 (Lch), TP9 (Rch)
• Adjustment location :
L772 .................................................... 450kHz
7. FM VT Check
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Settings : • Test point : TP1 (VT)
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Method : Set to FM 108.0MHz and check that the test point
is less than 8.0V. Then set to FM 87.5 MHz and
check that the test point is more than 0.5V.
8. FM Tracking Check
Settings : • Test point : TP8 (Lch), TP9 (Rch)
Method : Set to FM 98.0MHz and check that the test point
is less than 13dBµV.
9. DC Balance / Mono Distortion Adjustment
Settings : • Test point : TP3,TP4 (DC balance)
• Adjustment location : L771
• Input level : 60dBµV
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%.
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TP8 (Lch), TP9 (Rch) (Distortion)
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