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ELECTRICAL ADJUSTMENT -2/6
<TUNER Adjustment>
1. VT Check (AM)
Requirements
*
Measuring instrument: Digital multimeter
Test point: VT, GND
(1) Connect the digital multimeter to VT and GND.
(2) Set the unit function to AM, and adjust the receiving frequency to 1,710 kHz.
(3) Check that the digital multimeter indicates 9.0 V or below.
(4) Adjust the receiving frequency of the unit to 530 kHz.
(5) Check that the digital multimeter indicates 0.5 V or above.
2. VT Adjustment and Check (FM)
Requirements: Same as Item 1.
Adjustment point: L907
(1) Connect the digital multimeter to VT and GND.
(2) Set the unit function to FM, and adjust the receiving frequency at 108.0 MHz.
(3) Adjust L907 so that the digital multimeter indicates 7.0
±
0.1 V.
(4) Adjust the receiving frequency of the unit to 87.5 MHz.
(5) Check that the digital multimeter indicates 1.5 V or above.
3. Clock Check (AM)
Requirements
*
Measuring instrument: Frequency counter
Test point: CLOCK (IC801 24PIN), GND
(1) Connect the frequency counter to CLOCK and GND.
(2) Set the unit function to AM, and adjust the receiving frequency to 1,710 kHz.
(3) Check that the frequency counter indicates 2,052 kHz
±
45 Hz.
<AM Adjustment>
Make sure that the following settings are done before adjustment.
Preparation
*
Measuring instruments:
Standard Signal Generator (S.S.G.) / Loop antenna / Oscilloscope / Millivoltmeter / Dummy resistor (6
Ω
)
(1) Connect the measuring instruments as shown in the diagram below.
(2) Keep a distance of 60cm between the loop antenna of signal generator and the one connected to the unit.
4. IF Adjustment
Requirements
*
Test point: SP OUT (Lch, Rch)
Adjustment point: L802
(1) Adjust the S.S.G. setting to AM; carrier at 1000 kHz with 30% modulation, and source at 1 kHz, position output at maximum.
(2) Adjust the unit to AM 1000 kHz.
(3) While monitoring the 1 kHz waveform through oscilloscope, decrease the S.S.G. output level (till slight noises appear in the waveform).
(4) Adjust L802 so that the millivoltmeter indicates maximum.
Summary of Contents for MSX-R14
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