Aiwa Z-A85 Service Manual page 42

<FM Adjustment>
Make the following preparations for FM adjustment.
Preparations
• Standard Signal Generator (S.S.G.) / Loop antenna / Oscilloscope / Millivoltmeter / Dummy resistance (6W)
1) Connect the unit and measuring instruments as shown in the diagram below.
2) Connect the output of S.S.G. to the antenna input of the unit.
Standard Signal Genertaor
7. Tracking Adjustment (FM)
Requirements: As instructed in preparations.
• Adjustment point: L903
1) Set S.S.G. to FM; carrier of 87.5MHz with 75kHz modulation, and source at 1KHz.
2) Tune the receiving frequency of the unit at FM87.5MHz.
3) While monitoring the waveform at 1kHz through the oscilloscope, lower the output level of S.S.G. maximum (till a certain degree of
noise is monitored).
4) Adjust L903 so that the millivoltmeter points maximum.
8. Separation Check (FM)
Requirements: As instructed in preparations.
1) Set S.S.G. to FM; carrier of 98MHz with 67.5kHz modulation, source at 1kHz, and output at 60dBuV.
2) Switch S.S.G. to PILOT ON, and set PILOT at 7.5kHz.
3) Tune the receiving frequency of the unit at FM98MHz.
4) Allow the output of S.S.G. only from Lch, and check that the difference between Lch and Rch is 25dB or above.
5) Apply the above check to Rch.
9. Auto-Stop Check (FM)
Requirements: As instructed in preparations.
1) Set S.S.G. to FM; carrier of 98MHz with 75kHz modulation, source at 1kHz, and output at 10dBuV ~ 35dBuV or less.
2) Apply the tuning search function, and check that the unit automatically stops at FM98MHz.
AC MILLIVOLTMETER
SET
DUMMY
CH1
LOAD
FM ANT
SPOUT(L)
SPOUT(R)
Ω
6
– 42 –
OSCILLOSCOPE
OUTPUT
CH2
CH2
CH1