Marantz 4270 - Marantz 4270 AM Alignment Procedure

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17. TEST EQUIPMENT REQUIRED FOR SERVICING
Table 1 lists the test equipment required for servicing the Model 4270 Receiver.
Item Manufacturer and Model No.
AM Signal Generator
Signal source for AM align-
ment.
Used with AM Signal gen-
Test Loop
erator.
FM
Signal
Generator
Less
than
0.3%
distorsion.
Signal
source
for
FM
align-
ment.
Stereo Modulator Less than 0.3% distorsion. Stereo separation alignment
and trouble shooting.
Frequency Counter MPX Oscillator adjustment
(VCO).
saad
Weston Model CVO-100P, less | Sinewave and squarewave sig-
than 0.02% residual distortion | nal source.
is required.
High sensitivity with DC hori-
zontal and vertical amplifiers.
With AC, DC, RF range.
Audio Oscillator
Oscilloscope
Waveform
analysis
and
trouble
shooting and ASO alignment.
Voltage measurements.
Trouble shooting.
Simpson, Model 390 Monitors primary power to
| Amplifier.
AC Ammeter Commercial Grade (1-10A) Monitors amplifier output un-
der short circuit condition.
Circuit Tester
AC Wattmeter
Line Voltmeter Commercial Grade Monitors potential of primary
(0-150V AC) power to amplifier.
Variable Autotransformer| Powerstat, Model 116B
(0-140V AC, 10 amps)
Shorting Plug
Adjusts level of primary
power to amplifier.
Use phono plug with 600
ohm across center pin and
shell.
Output Load Commercial Grade Provides 8-ohm load for
(8 ohms, +1% 100W) amplifier output termination.
Output Load Commercial Grade Provides 4-ohm load for
(4 ohms, +1% 100W) amplifier output termination.
Table 1. Test Equipment Required for Servicing
Shorts amplifier input to
eliminate noise pickup.
18. AM ALIGNMENT PROCEDURE
18.1 AM IF Alignment
1. Connect a sweep generator to the J153 and an alignment scope to the test point ©.
2. Rotate each core of IF transformer L153 and L154 for maximum height and flat top sym-
9 metrical response.