Aiwa NSX-R90 Service Manual page 48

ELECTRICAL ADJUSTMENT-4/6
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<FM Adjustment>
Before starting the FM adjustment, perform the preparation shown below.
Preparation
Ÿ
Measuring equipment: Standard signal generator (S.S.G), oscilloscope, milli-volt meter and dummy resistor (6Ω)
1) Connect measuring equipment as shown below.
2) Connect the S.S.G. output to antenna input of the NSX-R90.
Standerd Signal Genertaor
7. Tracking Adjustment
Conditions: The same conditions as specified in Preparation.
Ÿ
Adjustment point: L904
1) Set up the S.S.G.. to FM, carrier 87.5 MHz, modulation 75 kHz and source 1 kHz.
2) Tune the reception frequency to 87.5 MHz.
3) While observing the 1 kHz waveform with an oscilloscope, decrease the S.S.G.. output level. (Decrease until small noise is visible on
waveform.)
4) Adjust L904 until the milli-volt meter reading becomes maximum.
8. Separation Check
Conditions: The same conditions as specified in Preparation.
1) Set up the S.S.G.. to FM, carrier 98 MHz, modulation 67.5 kHz, source 1 kHz and output 74 dBuv.
2) Switch the S.S.G. to PILOT ON and set the PILOT to 7.5 kHz.
3) Tune the reception frequency to FM 98 MHz.
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4) Set the S.S.G. output to L-channel only. Check that the level difference between L-channel and R-channel is 25 dB or more.
L 13942296513
5) Check the R-channel in the same way.
9. Auto Stop Check
Conditions: The same conditions as specified in Preparation.
1) Set up the S.S.G.. to FM, carrier 98 MHz, modulation 75 kHz, source 1 kHz and output 35 dBuv or less.
2) Let the NSX-R90 start the Tuning Search. Check that the Tuning Search stops at FM 98 MHz automatically.
10. DC Balance/Mono Distortion Adjustment
Settings : Ÿ Test point : TP8, TP9 (DC balance)
Ÿ Adjustment location : L801
Ÿ Input level : 60dBuV
Set to FM 98.0 MHz and adjust L801 so that the voltage between TP2 and TP3 is 0 V ± 500 mV.
Method :
Next, check that the distortion is less that 1.2%.
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SET
FM ANT
SPOUT(L)
SPOUT(R)
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2 9
8
AC MILLIVOLTMETER
DUMMY
CH1 CH2
LOAD
CH1
6
Q Q
3 6 7 1 3 1 5
co
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-48-
9 4 2 8
OSCILLOSCOPE
OUTPUT
CH2
0 5 8 2 9 9 4 2 8
m
9 9
9 9