-48-
<FM Adjustment>
Before starting the FM adjustment, perform the preparation shown below.
Preparation
Measuring equipment: Standard signal generator (S.S.G), oscilloscope, milli-volt meter and dummy resistor (6
Ω
)
1) Connect measuring equipment as shown below.
2) Connect the S.S.G. output to antenna input of the NSX-R90.
7. Tracking Adjustment
Conditions: The same conditions as specified in Preparation.
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.
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.
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 :
Test point : TP8, TP9 (DC balance)
Adjustment location : L801
Input level : 60dBuV
Method :
Set to FM 98.0 MHz and adjust L801 so that the voltage between TP2 and TP3 is 0 V
±
500 mV.
Next, check that the distortion is less that 1.2%.
DUMMY
SPOUT(L)
AC MILLIVOLTMETER
CH2
CH1
6
OUTPUT
OSCILLOSCOPE
CH2
CH1
LOAD
SET
Standerd Signal Genertaor
FM ANT
SPOUT(R)
ELECTRICAL ADJUSTMENT-4/6
www. xiaoyu163. com
QQ 376315150
9
9
2
8
9
4
2
9
8
TEL 13942296513
9
9
2
8
9
4
2
9
8
0
5
1
5
1
3
6
7
3
Q
Q
TEL 13942296513 QQ 376315150 892498299
TEL 13942296513 QQ 376315150 892498299
