Panasonic Technics ST-CH7L - Page 5

ST-CH7L
ST-CH7L
m MEASUREMENTS AND ADJUSTMENTS
This TUNER (ST-CH7L) is powered by the amplifier (SU-CH7). To adjust it or check operations as a separate unit,
follow the steps below.
1. Apply a power supply voltage of AC 23 V to [yZe and iZey)-
2. Power supply switch: ON
HOW TO CONNECT
Note:
Apply a power supply voltage of AC 23 V
to pieydehd and paeygeyy by using a Voltage
Controller. If itis not available, use a
Power Supply Fixture
(SZZA1058C)
Voltage controller
Power Supply Fixture (SZZA1058C) OR
instead. © a
e ADJUSTMENT POINT
AM
LOOP
ANT
AM
ANT FM ANT TO AMP
750
7
Z202 LINE OUT LINE OUT
(Leh) (Reh)
FM mono
distortion
FM offset
PLL clock Frequency
FM MPX VCO
(I9kHz)
eFM ADJUSTMENT
Control positions and equipment used
@FM signal generator (FM-SG)
Frequency counter
Choke coil (100 LH)
e Resistor (100 kQ)
Stereo modulator
e Distortion analyser
DC electronic voltmeter (EVM)
Note: For Z201 (AM ANT and OSC coil), Z202 (AM-IFT), they are supplied as adjusted parts. So, do not turn the cores of the parts.
If is not necessary to adjust the AM circuit.
FM OFFSET VOLTAGE AND MONO DISTORTION
ADJUSTMENT FM SIGNAL GENERATOR CONDITION
Modulation
1. Test equipment connection is shown in figure. Modulation frequency
. Set the unit to “FM” mode. Output level
. Set the radio frequency display and signal generator to
100.10 MHz.
. Adjust the core of T201 so that the voltage measured in signal
mode is 0 mV (0+20 mV) in 300 mV range.
. Adjust T202 so that the distortion factor of L-CH and R-CH is
minimized.
. Repeat steps 4 and 5.
Note: The adjusting screwdriver used should be made of resin.
FM MPX VCO ADJUSTMENT
. Test equipment connection is shown in figure.
. Set the unit to “stereo” position.
. Set the radio frequency display and signal generator to
100.10 MHz.
. Adjust VR501 for 19 kKHz+30 Hz on frequency counter reading.
FM ANT (759)
USING ALTERNATE SYSTEM
1. Receive the stereo broadcast.
2. Adjust VR301 until stereo indicator lights up. Fix the arm of
VR301 as shown in gifure. “Stereo”
FM SIGNAL GENERATOR CONDITION
Modulation
Modulation frequency .... OkHz
Output level
. “Stereo” OFF position
. “Stereo” ON position
(Indicator lighting)
Adjust point of pilot circuit
PLL CLOCK FREQUENCY ADJUSTMENT
Use a high impedance probe.
Frequency counter
1. Test equipment connection is shown in figure.
2. Adjust CT101 for 2070+0.010 kHz (2050+0.010 kHz...GC only)
on frequency counter reading.