Marantz 105B - Advanced Alignment and Servicing Equipment; Stereo Separation Alignment; Muting Circuit Alignment; Test Equipment Required for Servicing

.. _-- ........... .
4.1 STEREO Separation Alignment
1. Set the FM SG to provide 1 K/-lV at 98 MHz .
Tune the receiver
to the same frequency perfectely (so that the VTVM connected to the test
point ® gives no reading) .
2. Modulate
the FM SG with stereo composite signal consisting of subchanged signal only (of
course a pilot signal must be included).
Adjust the core of L 110 for maximum audio output, then, modulate the FM SG with a stereo
composite
signal consisting
of L or R channel only, and adjust the trimming resistor R 161 for
maximum and equal separation in both channels.
4.2
Muting Circuit Alignment
1. Set the FM SG output to provide 25 /-lV (lHF) at 98 MHz and tune the receiver to the same
frequency.
Adjust the trimming resistor R153 for the threshold level of 25 /-lV (during this adjustment
turn the MUTING pushswitch "on").
5. Test Equipment Required for Servicing
Table 1 lists the test
equipment required for servicing the Model 105 B Tuner.
Item Manufacturer and Model No.
Use
AM Signal Generator Signal
source for
AM
align-
ment
Test Loop
Used with AM Signal generator
I
FM Signal Generator
Less than 0.3% distortion Signal source for FM align-
ment
Stereo Modu lator
Less than 0.3% distortion Stereo separation alignment
and
trouble shooting
A
udio Oscillator
I
Weston Model CVO- l00P, less
than
0.02%
residual distor-
tion is required
Sinewave and squarewaves sig-
nal source
Osc ill oscope
High sensitivity with DC hori-
zontal and vertical amplifiers
Waveform analysis and Trou-
ble Shooting, and ASO
align-
ment
VTVM With AC, DC, R F range Voltage measurements
Circuit Tester
Trouble Shooting
Table 1. Test Equipment Required for Servicing
4