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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.
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