Marantz SR620 - Page 5

Item
3. TEST EQUIPMENT REQUIRED FOR SERVICING
Use
This table lists the test equipment required for servicing the Model SR620/SR620L/SR520/SR520L Stereophonic Receiver.
AM Signal Generator
Signal source for AM alignment
Test Loop
Use with AM Signal Generator
FM Signal Generator
MPX Signal Generator
Signal source for FM alignment
Stereo separation alignment and trouble shooting
Distortion Analyzer
Audio Oscillator
AC VTVM
Distortion measurements
Sinewave and squarewave signal source
Voltage measurements (AC)
Oscilloscope
Waveform analysis and trouble shooting
Frequency Counter
MPX Oscillator adjustment (VCO)
Circuit Tester
Trouble shooting
DC VTVM
Voltage measurements (DC)
AC Wattmeter
Monitors primary power to tuner
Line Voltmeter
Monitors potential of primary power to tuner
Variable Autotransformer
DC Didital Voltmeter
Adjusts level of primary power to tuner
Adjust the DC offset of main amplifier output. (SR620/SR620L)
4. TUNER ALIGNMENT PROCEDURES
A dummy resistor of 47 kohms must be connected across the tuner output terminals before alignment.
4.1 FM Alignment Procedures (Selector switch in the ‘‘FM” position, Mode switch in the MONO Position.)
AUTO/MANU Switch in the “MANU” Position (SR620/SR620L)
1. FM RF Alignment
Signal Source
Connection
Signal
Frequency
Indicator
Connection
Set the Digital
Readout Frequency
Adjust:
RF generator to FM antenna
terminals through matching
network (300 ohms, balanced)
Maintain RF level below
limit.
VTVMto Lor R
channel output
(J110)
FRONT END IFT L8 for
maximum output and
distortion.
RF generator 71mV output
to FM antenna terminals
through matching network.
(300 ohms, balanced)
“O"' center meter or
DC current meter in
100A range between
(J117 and J118)
L101 core so that the
meter indicates its center
or may read ‘'O"’.
RF generator 1 mV output
to FM antenna terminals
through matching network.
(300 ohms, balanced)
Distortion meter to
Lor R channel
output (J110)
98.0 MHz
L102 core for minimum
distortion.
RF generator to 12.5uV
Distortion meter to
L or R Channei
Output (J110)
Turn R117 until output
is defeated, then re-adjust
R117-to the point where
output is obtained again.