Electrical Adjustment - Aiwa NSX-WK790 Service Manual

ELECTRICAL ADJUSTMENT

TUNER C.B
3
5
7
8
9
3
3
L941
5
TC943
< TUNER SECTION >
1. Clock Frequency Check
Settings: • Test point: TP2 (CLK)
Method: Set to MW1602kHz and check that the test point is
2052kHz±45Hz.
2. MW VT Adjustment
Settings: • Test point: TP1 (VT)
• Adjustment location: L981 (3/3)
Method: Set to MW 1710kHz and adjust L981 (3/3) so that
the test point becomes 8.0V±0.05V. Then set to
MW 530kHz and check that the test point is more
than 0.3V.
3. MW Tracking Adjustment
Settings: • Test point: TP6(Lch), TP7(Rch)
• Adjustment location:
L981 (1/3) ............................................ 603kHz
TC941 ................................................ 1404kHz
Method: Set up TC941 to center before adjustment.
The level at 603kHz is adjust to max. by L981
(1/3). Then the level at 1404kHz is adjust to max.
by TC941.
4. SW VT Adjustment
Settings: • Test point: TP1 (VT)
• Adjustment location: L942
Method: Set to SW 17.9MHz and adjust L942 so that the
test point becomes 7.0V±0.05V. Then set to SW
5.9MHz and check that the test point is more than
0.3V.
CN701
GND
TP6
10 12
TP7
(LCH)
(RCH)
TC941
L981
(1/3)
(3/3)
L942
FFE801
4 2
TP3
30
L772
4
TP1
(VT)
6
2 4
8
5. SW Tracking Adjustment
Settings: • Test point: TP6 (Lch), TP7 (Rch)
• Adjustment location:
L941 .................................................... 5.9MHz
TC943 ................................................ 17.9MHz
Method: Set up TC943 to center before adjustment.
The level at 5.9MHz is adjust to max. by L941. Then
the level at 17.9MHz is adjust to max. by TC943.
6. FM VT Check
Settings: • Test point: TP1 (VT)
Method: Set to FM 108.0MHz and check that the test point is
less than 8.0V.
Set to FM 87.5MHz and check that the test point is
more than 0.5V.
7. FM Tracking Check
Settings: • Test point: TP6 (Lch), TP7 (Rch)
Method: Set to FM 98.0MHz and check that the test point is
less than 9.0dBµV.
8. AM IF Adjustment
Settings: • Test point: TP6 (Lch), TP7 (Rch)
• Adjustment location:
L772 .................................................... 450kHz
Method: Adjust L772 so that the output becomes max.
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%.
40
TP4
TP2
(CLK)
IC771
L771
9
TP6 (Lch), TP7 (Rch) (Distortion)
9
1