Marantz 4230 - Test Equipment Required for Servicing; AM Alignment Procedure; AM IF Alignment; AM Frequency Range and Tracking Alignment

17. TEST EQUIPMENT REQUIRED FOR SERVICING
Table 1 lists the test equipment required for servicing the Model 4230 Receiver.
Item
Manufacturer and Mode! No.
Use
AM Signal! Generator
Signal source for AM align-
ment.
Test Loop
Used with AM Signal generator.
FM Signal Generator
Less than 0.3% distortion
Signal source for FM align-
ment.
Stereo Modulator
Less than 0.3% distortion
Stereo separation alignment
and trouble shooting.
Audio Oscillator
Weston Model CVO-100P,
less than 0.02% residual dis-
tortion is required.
Sinewave and squarewave sig-
nal source.
Oscilloscope
High sensitivity with DC hori-
zontal and vertical amplifiers.
Waveform analysis and trouble
shooting and ASO alignment.
VTVM
Circuit T ester
AC Wattmeter
AC Ammeter
Line Voltmeter
Variable Autotransformer
(0-140VAC, 10 amps)
With AC, DC, RF range
Voltage measurements.
Trouble shooting.
Simpson, Model 390
Monitors primary power to
Amplifier.
Commercial Grade (1-10A)
Monitors amplifier output un-
der short circuit condition.
Commercial Grade
(0-150VAC)
Monitors potential of primary
power to amplifier.
Powerstat, Model 116B
Adjusts level of primary power
to amplifier.
Shorting Plug
Use phono plug with 600
ohm across center pin and
shell.
Shorts amplifier input to elimi-
nate noise pickup.
Output Load
(8 ohms, 0.5% 100W)
Commercial Grade
Provides 8-ohm load for am-
plifier output termination.
Output Load
(4 ohms, 0.5% 100W)
Commercial Grade
Provides 4-ohm load for am-
plifier output termination.
Table 1. Test Equipment Required for Servicing
18. AM ALIGNMENT PROCEDURE
18.1 AM IF Alignment
1. Connect a sweep generator to J107 and an alignment scope to the test point ® .
2. Rotate each core of IF transformer L116 and L117 for maximum height and flat top
symmetrical response.
18.2 AM Frequency Range and Tracking Alignment
1. Set AM signal generator to 525KHz. Turn the tuning capacitor fully closed (place the tuning
pointer at the low end.) and adjust the oscillator coil L115 for maximum audio output.