*TM-11-5821-284-34
a.
Operational Test. The procedures given in the
equipment covered in this manual.
Failure to follow
requirements of TB SIG 291 could result in injury or DEATH.
equipment performance check (section IV) are used for
locating a defective stage within the antenna. If a fault
3-4.
General Precautions
indication is obtained when performing the operational tests,
a.
When testing or troubleshooting the antenna,
refer to the troubleshooting chart (d) below for further
make sure that the power supply voltage is correct. Abnormal
information on the procedure to use for stage isolation.
supply voltages often affect frequency and stability
b.
Signal Sampling. This procedure consists of
characteristics and the output or gain of the circuits.
sampling signals at applicable points in the antenna to verify
b.
Do not come in contact with components or
overall performance. These tests verify antenna performance
wiring when power is applied to the antenna.
and the indications provided by the antenna indication system.
3-5.
Antenna Troubleshooting
c.
Troubleshooting Aids. The illustrations listed
Antenna troubleshooting consists of operational testing and
below will be useful during troubleshooting of the antenna.
signal sampling to check the overall capability of the antenna.
If proper results are not obtained during these tests or If other
abnormalities are observed, refer to the troubleshooting chart
(d(2)) below to isolate the probable cause of the trouble.
Figure No
Illustration
5-61
437S-1/1A/1C coupler assembly test points (sheet 1of 2).
5-62
437S-1/1A/1C coupler assembly test points (sheet 2 of 2)
5-7
437S-1/1A/1C coupler connec tor J2 test points
5-8
Servomaplifier circuit board A1 test points
5-9
A1A1 through A1A6 flat pack test points
5-10
Operational amplifier A1AR1 test points.
FO 6-2
AS-2285/ARC (Model 437S-1/1A/1C) Schematic Diagram
FO 6-3
AS-2285/ARC (Model 437S-1B) Schematic Diagram
FO 6-4
AS-2285/ARC Antenna Waveforms
d.
(2) Troubleshooting Chart.
Troubleshooting Checks.
General. The troubleshooting chart, (2) below, is an aid in
NOTE
locating troubles In the individual circuits of an antenna stage
Perform the equipment
after trouble has been isolated to a specific stage or circuit of
performance
tests
in
the antenna through the equipment performance check
section IV; when a test
(section IV) or signal sampling tests (b), above. Refer to the
step is failed, refer to the
schematic wiring diagrams list , above, for further aid in
applicable test of the
troubleshooting the antenna circuits after trouble has been
troubleshooting chart.
Isolated to specific stage.
Sentence No.
Trouble symptom
Probable cause
Corrective action
1
Antenna reflected power is more
Defect In coupler or antenna
Proceed to item 2 for further
than 25% of forward power
circuits
Isolation of trouble
2
a. Incorrect waveform at J2-K
a. Defect In servo amplifier,
a. Replace coupler.
when pin 10 or pin 12 of
pulsing, or manual override
circuit board Al is grounded
circuits
b. Correct waveform at J2-K
b. Defect in sequencing servo
b. Replace coupler
when pin 10 or 12 of circuit
control, or servo motor circuits
board Al is grounded but actu-
ator arm does not operate
Section III. DIRECT SUPPORT REPAIR AND REPLACEMENT
assembly Al.
3-6.
General
(FO 6-5)
Replacement of a radome or coupler is the only repair
a.
authorized at the direct support maintenance category. When
Remove fourteen (14) screws H14 from the
a radome or coupler is found to be malfunction-ing, replace it
base of the antenna.
with a new part. Send the malfunctioning part to a general
b.
Carefully pull coupler assembly from the radome
support maintenance facility for repair.
assembly. This can easily be done by grasp-
3-7.
Separation of Radome Assembly A2 and Coupler
3-2
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