Technics Quartz SA-R230 - Page 9

Mi MEASUREMENTS AND ADJUSTMENTS
FM
Control positions and equipment used
e FM signal generator (AM and FM-SG).
e AC and DC electronic voltmeter (EVM)
e Frequency counter
e Resistor (100 kQ)
e Stereo modulator
e Distortion analyser
e Oscilloscope
Note: For 2201, 2202, Z321, L321, L322 and L324, adjusted parts are supplied. So, do not turn the cores of these parts.
FM MONO DISTORTION ADJUSTMENT
1. Test equipment connection is shown in figure.
2. Set the unit to “FM” position.
3. Set the radio frequency display and signal generator
to 100.10 MHz.
. Adjust T201 core so that voltage measured in signal
mode is OmV (02+20mV) in 300mvV range.
. Adjust T202iso 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 nearly the same with each other to minimum.
Note:
The adjusting screwdriver used should be made of
resin.
MPX VCO ADJUSTMENT
. Test equipment connection is shown in figure.
. Set the unit to “FM auto” position. ,
. Place the radio frequency display and signal
generator to 100.10 MHz.
. Adjust VR301 for 19.00+0.03kHz on frequency
counter reading.
%* USING ALTERNATE SYSTEM
1. Apply stereo signal from generator or receive the
stereo broadcast.
2. Adjust VR301 until stereo indicator lights up.
Cement arm of VR301 as shown in figure.
FM STEREO SEPARATION ADJUSTMENT
1.Test equipment connection is shown in figure.
2.Set the unit to "FM” mode.
3.Set the radio frequency display and signal generator to
100.10MHz.
4.Adjust VR302 so that the R-CH output is minimized when
‘stereo modulator is in ”L”(L-CH modulation) mode.
FM SIGNAL GENERATOR CONDITION
Modulation
1kHz
(MONO)
Choke coil
WO
(non-modulation)
66dB
FREQUENCY
FM ANTENNA COUNTER
TERMINAL
Abo
® - ©) - ©: Stereo OFF position
-@© : Stereo ON position
(indicator lighting)
© : Adjust point of Pilot circuit
FM SIGNAL GENERATOR CONDITION
Modulation Stereo “L’” mode or “‘R”
mode 90%, Pilot 10%
Modulation frequency 1kHz (Pilot 19kHz)
Output level
LPF (fc= TSkHz~ 19kHz)
FM STEREO DISTORTION ADJUSTMENT
1. Test equipment connection is shown in figure.
2. Set the unit to “FM” mode.
3. Set the radio frequency display and signal generator to
100.10 MHz.
4. Adjust L1 so that the distortion factor of L-CH is minimized.
5. Make sure that the distortion factors of L-CH and R-CH are
nearly the same with each other to minimum.
Notes:
1.The adjusting screwdriver used should be made of resin.
2.L1 should be rotated no more 1/4 turn (90 deg.) on either
side.
e Adjustment points
AM ANT
FM offset
coil
FM MONO
DISTORTION
coil
FRONT END PACK
FM SIGNAL GENERATOR CONDITION
Modulation Stereo “L” mode or “‘R”
mode 45%, Pilot 10%
Modulation frequency
Output level
A fees] O
Stereo modulator Adjust within +90°
Output mode... Lor R
FM STEREO
SEPARATION Adj.
MPX VCO Adj.