Daewoo AMI-921DP, Руководство по обслуживанию

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4
ADJUSTMENTS
1. TUNER SECTION
TEST EQUIPMENT
1. Signal Generator with a frequency range of FM broadcast.
2. Oscilloscope with a side amplifier of approximately 100 KHz.
3. FM 75/50
Ω
dummy antenna.
4. VTVM
FM ALIGNMENT
1. Turn on the FM signal generator and the VTVM allowing 15 minutes warming-up period.
2. Connect the VTVM across the headphone jack or speaker terminal.
3. Set signal generator frequency as listed in ALIGNMENT CHART and maintain a sufficient output level to provide an
indication on VTVM.
NOTE
1. Use a screwdriver with plastic or ceramic grip for all adjustments.
2. Standard test frequency 1 KHz and deviation 75 KHz for FM.
- FM RF, IF ALIGNMENT CHART -
Unless other specified set being switched FM mode, adjust generator's frequency to center of the FM band where no FM broadcast exists
Otherwise adjustment of FM usable sensitivity, frequency range for FM band are not needed, but confirm these data are satisfied with specifi-
cation.
CAUTION : When realigning the FM receiving frequency the highest end of the frequency range should not be more than 108 MHz and the
lowest end of the frequency range should not be less than 87.5 MHz, in order to comply with FTZ regulation in West Germany.
2. CD SECTION
Note:
1. Use the oscilloscope with more than 10M
Ω
impedance.
2. Clean an object lens by an applicator with natural detergent when the signal level is lower than specified value
with the following checks.
RF LEVEL CHECK
1. Connect oscilloscope to test point TP502 and IC502
Pin66 on CD PCB.
2. Press power switch on.
3. Put test disc(TCD-781) in and press play button then
pause button.
4. Confirm that oscilloscope waveform is clear. Clear
RF signal waveform means that the shape"#"can be
clearly distinguished at the center of waveform.
5. Adjust RV501 to get a clear waveform and maximum
amplitude.
Step Item Input Circuit Setup Output Circuit Setup Tuner Setting Adjust Point Adjustment
1
FM IF
Adjustment
Connect stereo signal
generator to FM ANT
terminal (J001)
Connect DC voltme-
ter to edge R201
FM98MHz75KHz
Dev. 26dB
µ
L203 Adjust forDC 0V
±
0.1V
2
Auto Stop
Sensitivity
Connect stereo signal
generator to FM ANT
terminal (J001)
Connect DC voltme-
ter to edge of RV201
FM 98MHz
75KHz Dev.
26dB
µ
RV201
Adjust for DC
1.17V
±
0.02V
Confirm stereo indica-
tor is lighted and L/R
channel is separated.
SET
FM Antenna
Terminal(75 ohm)
Carrier Frequency : 98MHz
Output Level : 26dBuV
Modulation:Audio 1kHZ, 75kHz Deviation
FM RF SSG
75 ohm Coaxal
Level : 1.2+0.3Vp-p
RF Signal Waveform
VOLT/DIV : 200mV
TIME/DIV : 50ns