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M@ MEASUREMENTS AND ADJUSTMENTS
e AM/FM TUNER
Control positions and equipment used
e AM and FM signal generator (AM and FM-SG)
e Stereo modulator
e
Distortion analyser
® Oscilloscope
e AF Oscillator
AC and DC electronic voltmeter (EVM)
Frequency counter
Choke coil (100 tH)
Resistor (330kQ)
Capacitor (200 pF)
Note: For T226 (AM-IFT) and L227 (AM OSC coil), adjusted parts are supplied.
So, do not turn the cores of this parts.
AM-RF ADJUSTMENT
. Test equipment connection is shown in figure.
. Set the unit to "AM" position.
. Place the radio frequency display and signal
generator setting to 610kHz.
. Adjust L226 for maximum output.
. Place the radio frequency display and signal
generator setting to 1500kHz.
. Adjust CT225 for maximum output.
. Repeat steps 3.~6.
Note:
Antenna input level must be as low as possible
being free from AGC.
FM-RF ADJUSTMENT
1. Test equipment connection is shown in figure.
2. Place unit into "FM" position.
3. Place the radio dial and signal generator setting to
100.10MHz.
Add weak input so that noise is
included in the output waveform.
4. Adjust CT201 and T225 for maximum
output.
Note:
As three output reading will be present, adjustments
must be made at center frequency.
FM MONO DISTORTION ADJUSTMENT
. Test equipment connection is shown in figure.
. Set the unit to "FM" position.
. Place the radio frequency display and signal
generator setting to 100.10 MHz.
. Adjust T227 core so that voltage measured in signal
mode is OmV (0+30mV) in 300mvV range.
. Adjust T225 so that the distortion factor of Lch is
minimized.
. Repeat steps 4 and 5 a few times.
. Make sure that the distortion factors of Lch and Rch
are at minimum and nearly equal.
Note:
The adjusting screwdriver used should be made of
resin.
AM SIGNAL GENERATOR CONDITION
Modulation scsi cscesicscceceecscetect 30
Modulation frequency.............
OSCILLO
SCOPE
L225
Speaker
(AM ANT)
terminal
p
FM SIGNAL GENERATOR CONDITION
Modulation
Modulation frequency
Output level
AC EVM
OSCILLOSCOPE
FM-SG
FM SIGNAL GENERATOR CONDITION
Modulation
Modulation frequency
Output level
FM ANT
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MPX VCO ADJUSTMENT
1
2.
3.
4.
5.
Test equipment connection is shown in figure.
Set the unit to "FM auto" position.
Place the radio dial and signal genarator setting to
100.10 MHz.
Adjust VR251 for 38kHz+0.05 Hz on frequency
counter reading.
Modulate the pilot by 8% and make sure that the
stereo indicator lights up.
* USING ALTERNATE SYSTEM
1:
2.
Apply stereo signal from generator or receive the
stereo broadcast.
Adjust VR251 until stereo indicator lights up.
Cement arm of VR251 as shown in figure.
e CASSETTE DECK
MEASUREMENT CONDITION:
¢ Make sure heads are clean
* Make sure capstan and pressure roller are clean
HEAD AZIMUTH ADJUSTMENT (DECK A, B)
1;
2:
Test equipment connection is shown in figure.
Playback the azimuth adjusted part (@kHz, —20dB)
of the test tape (QZZCFM) and regulate the angle
adjusting screw so that the outputs of L-CH and
R-CH are maximized.
(When the adjusting
positions are different with L-CH and R-CH, find a
position where the outputs of L-CH and R-CH are
balanced, and then make the adjustment.)
. At the same time, draw a lissajous waveform and
eliminate phase deflection.
. After the adjustment, apply screw-lock to the angle
adjusting value.
TAPE SPEED ADJUSTMENT (DECK A, B)
. Test equipment connection is shown in figure.
. Set the unit to "TAPE" position.
. Playback the middle part of the test tape
(QZZCWAT).
. Adjust VR401 in the motor so that the output is
1.
2
3.
4.
within the standard. (DECK A, B)
FM SIGNAL GENERATOR CONDITION
Modulation
Output level
FREQUENCY
COUNTER
@®-—@® ©-—©: Stereo OFF position
®-@:
Stereo ON position
{indicator lighting)
©: Adjust point of Pilot circuit
TEST TAPE:
eHead azimuth adjustment (8kHz, —20dB): QZZCFM
eTape speed adjustment (83kHz, —10dB): QZZCWAT
¢Normal reference blank: QZZCRA
Oscilloscope
Record, Playoack Head
Azimuth Screw
LINE OUT
Speaker terminal
Digital trequency
counter
DECK B Standard value: 3000+20Hz
DECK A Standard value: 3000+ 45Hz
BIAS OSCILLATION ADJUSTMENT (DECK A)
Test equipment connection is shown in figure.
Set the unit to "TAPE" position.
Place cassette deck into REC mode.
Adjust L355 for 95~100kHz on frequency counter
reading.
TP305 # TP306
a
ins
Ge
=
Digital frequency
counter
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