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<Tuner Section>
1. AM VT Check
Requirement
•
Measuring instrument: Digital multimeter
Test points: VT, GND
1) Connect the digital multimeter between VT and GND.
2) Set the function to AM and the receiving frequency to 1,710kHz.
3) Check that the digital multimeter indicates 9V or less.
4) Tune to the receiving frequency to 530kHz.
5) Check that the digital multimeter indicates 0.5V or above.
2. FM VT Adjustment and Check
Requirement: As instructed in 1.
•
Adjustment location: L907
1) Connect the digital multimeter between VT and GND.
2) Set the function to FM and the receiving frequency to 108.0MHz.
3) Adjust L907 so that the digital multimeter indicates 7.0V ± 0.1V.
4) Tune to the receiving frequency to 87.5MHz.
5) Check that the digital multimeter indicates 1.5V or less.
3. AM Clock Check
Requirement
•
Measuring instrument: Frequency counter
Test points: CLK, GND
1) Connect the frequency counter between CLK and GND.
2) Set the function to AM and the receiving frequency to 1,710kHz.
3) Check that the frequency counter indicates 2,160kHz ± 45Hz.
<AM Adjustment>
Make the following preparation for AM adjustment.
Preparation
•
Measuring instruments: 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) Position the loop antenna connected to S.S.G. and the one connected to the unit 60cm apart.
4. AM IF Adjustment
Requirement: As instructed in preparation.
•
Adjustment location: L802
1) Set S.S.G. to AM, carrier of 1,000kHz with 30% modulation, source at 1kHz, and output approximately at MAX.
2) Tune the unit to the receiving frequency at AM 1,000kHz.
3) While monitoring the waveform at 1kHz through the oscilloscope, lower the output level of S.S.G. (till a certain degree
of noise is monitored).
4) Adjust L802 so that the Millivoltmeter indicates maximum.
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