Technics ST-G3

| ST-G3_ST-G3 |
FM SIGNAL GENERATOR CONDITION
Modulation 30%
Modulation frequency..
Output level
@ MEASUREMENTS AND ADJUSTMENTS
=
AM/FM
SIGNAL
STRENGTH
LEVEL
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.
. Change LCD display from frequency to dB by pressing
the FM signal button.
Control positions and equipment used
@ AMand FM signal generator (AM and FM-SG). @ Frequency counter
@ Stereo modulator @ Choke coil (100MH)
Distortion analyser @ Resistor (100k{2)
e
® Oscilloscope @® Ceramic capacitor (200pF)
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AC and DC electronic voltmeter (EVM)
So, do not turn the cores of these parts.
AM-RF ADJUSTMENT
. Test equipment connection is shown in figure.
. Set the unit to “AM” position.
Note: For 7201 (AM-IFT) and L203 (AM OSC coil), adjusted parts are supplied.
AM SIGNAL GENERATOR CONDITION
Modulation 30%
. Adjust VR101 so that 54 dB in indicated.
. Make sure that the signal strength level is 22 ~ 38 dB
when the input is 30 dB.
Adjustment points
. Place the radio frequency display and signal generator Modulation frequency 400 Hz AC EVM Oscilloscope
setting to 612 kHz. AM—SG UNIT
. Adjust L202 for maximum output. BS [ewe
. Place the radio frequency display and signal generator coe 00% FM det. coil RO oer NDAs! phe ere
(100.10 MHz) MENT MENT (612 kHz) (1503 kHz)
setting to 1503 kHz.
. Adjust CT201 for maximum output.
. Repeat steps 3 ~ 6.
Note: Antenna input level must be as low as possible
being free from AGC.
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 T101 core so that voltage measured in signal
mode is 0 mV (0 + 50 mV) in 300 mV range.
. Set the output mode of stereo modulation to “‘L” or ‘‘R”
. Adjust T102 so that “L’ channel ("R” channel) is
minimized.
. Repeat steps 4 ~ 6, and make sure that the distortion is
nearly same between ’’L” and ‘’R’”’ channels and is less
than 4%.
SEPARATION 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 VWR301 so that R output is minimized when
stereo modulator is in ‘’L’’ (L ch modulation) mode.
. The mode must be ‘’R” for ‘’R’’ channel; and L —»R,
R —»L separation must be 40 dB at least.
i
Capacitor Output
200pF terminal
FM SIGNAL GENERATOR CONDITION
Modulation «.-. 100%
Modulation frequency ... 400 Hz
Output level
DCEVM ACEVM
Choke
FM-SG UNIT coil
STEREO MODULATOR
Output mode
FM SIGNAL GENERATOR CONDITION
Modulation “L” mode or “‘R” mode 90%, Pilot 10%
1 KHz, Pilot (19 kHz)
L.R_Output
@@ -? terminal
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YeKeKe)=:) LPF (fc = 15 kHz ~ 19 kHz)
STEREO MODULATOR
VR30I VRIOI
Separation
adj. level adj.
Signal strength FM detector coil
(100.10 MHz)