necessary to extend the connector pins beyond the
6-2. Organization of Troubleshooting Procedures
connector shell. To accomplish connector pin extension,
a. General. The three steps in servicing the test
obtain corresponding pins from spare parts and wrap the
facilities set are
pins with electrical tape. Insert the plug ends of the
(1) Sectionalization of the fault.
insulated pins over the appropriate connector pins and
(2) Localization of the fault.
connect required test equipment.
(3) Isolation of the fault.
b. Sectionalization. The test facilities set consist of
6-3. Test Equipment Required
The following is a listing of test equipment required for
tracing the trouble is to locate the component or
troubleshooting the test facilities set. The associated
components at fault by the following methods:
manuals are also listed.
(1) Visual inspection. The purpose of visual
inspection is to locate faults without testing or measuring.
Except for the hybrid
Be certain that the components of
attenuator assembly, troubleshooting is based on the
test facilities set are disconnected
operational use of this equipment.
from the IFF set before performing
In the course of using this
The IFF set
equipment to maintain the IFF set, the operational or
contains transistors and integrated
maintenance tests called for in the IFF set manual may
circuits which could be damaged.
be used in determining the location of the fault in the test
facilities set. Procedures for isolating troubles in the test
Multimeter......................... Multimeter TM 11-6625-1559-12
d. Techniques. In performing the sectionalization,
Megger ............................. Ohm meter
ZM-21A / U
localization, and isolation procedures, the following
techniques may be applied:
AN / USM-281A
(2) Continuity checks.
e. Connector Pin Extension. When measurements
are to be made at connector pins (e.g. 1A1A1J10) it is
Section II. COMPONENT TROUBLESHOOTING
removed should be checked further to isolate the
replacement of parts before reading
b. Once the trouble has been isolated to the test
facilities set component and a spare is not available,
6-4. Visual Checks
measurements may be performed on that component.
Visually inspect the components of the test facilities set
for evidence of physical damage to extender boards,
insulation or sleeving of cables, mating parts of
Always disconnect the test facilities
connectors and couplings, operating controls of interface
set component from the IFF set test
adapter unit 1A1A1 and hybrid attenuator 2A1, and
broken, corroded, or bent connector pins.
6-5. Localization of Trouble
integrated circuits are used in the IFF
a. In troubleshooting the IFF set in accordance with
set, and continuity measurements by
the technical manuals for that equipment, the procedures
therein make use of the components of the test facilities
set. If the same fault(s) appear for similar assemblies of
the IFF set, using the same test setup in consecutive
6-6. Isolation of Trouble in Group 1
tests, a component of the test facilities set is probably at
a. General. Group I of the test facilities set
fault. When trouble is indicated in a component of the
provides four functions for testing the IFF set. These
test facilities set, replace that component with a spare (if
functions provide mounting for the antenna pedestal,
available) before making further tests. If the trouble is
simulation of the antenna, interface for he IFF set and
corrected by the replacement, then the component
associated radar, and interconnection