TM 11-6625-2398-14-4
insulation to higher category maintenance for repair.
with fine sandpaper. Brush two thin coats of paint on the
(3) Repair minor damage to cable insulation (para 4-1
bare metal to protect it from further corrosion. Refer to
la).
applicable cleaning and refinishing practices specified in
(4) Damaged adapters are not repairable; they must
TB734-0118.
For touchup painting, use light gray
be replaced with new ones.
enamel, formula No. 11 (per MIL-E-15090), type II, class
(5) Clean dirty connectors (para 4-8).
2 (semigloss).
b. Check operation of ATTENUATOR knob on the
4-10. General Troubleshooting Information
hybrid attenuator for looseness (para 4-1 lb).
c. Perform
troubleshooting
procedures
for
Troubleshooting this equipment is based upon the
suspected cables or fault isolation board (para 4-
operation of the test facilities set in a test configuration
12).
with the IFF set. If, in troubleshooting the IFF set, certain
4-7.
Downtime Maintenance
components of the test facilities set are defective, or
suspected of being defective (other than cables or
During downtime, inspect the equipment as described in
extender boards), higher category maintenance is
a through d below.
required. Troubleshooting the cables and fault isolation
a. Check that test facilities set equipment is
board of the test facilities set consists of continuity
complete and that quantities are the same as listed in
checks with a multimeter (para 4-12). The schematic
diagrams in chapter 6 are to be used as a guide in
b. Clean the transit case, hybrid attenuator case,
determining the connections to check for continuity. Any
and the accessory case surfaces, if required (para 4-8).
cable found to be defective should be sent to a higher
c. Touchup or refinish transit case, hybrid
category of maintenance for repair.
attenuator, and accessory case surfaces if required (para
4-11. Operator's Repairs and Adjustments
d. Calibrate hybrid attenuator as described in TB
a. Minor Repair of Cables. Repair minor cuts in
11-6625-2398-35 (to be done by higher category
cable insulation by covering it first with rubber tape, and
maintenance).
then with friction tape. If a cable is broken, ship
4-8.
Cleaning
defective cable to higher category of maintenance for
a. Hybrid Attenuator 1A1A1. Inspect the exterior
repair.
b. Replacement and Calibration of Hybrid
surfaces of the hybrid attenuator. The exterior surfaces
Attenuator Knob. If ATTENUATION control AT1 knob on
should be clean, free of dust, dirt and grease.
(1) Remove dust and loose dirt with a clean, lint-free
the hybrid attenuator either becomes loose or must be
cloth, item 2, appendix E.
replaced, it must be calibrated by higher category
maintenance.
WARNING
Cleaning compound is flammable and its
fumes are toxic.
Provide adequate
4-12.
Continuity Check of Cables and Extender
ventilation. DO NOT use near a flame.
Boards
(2) Remove grease, and ground-in dirt from the
components. Use a cloth dampened (not wet) with
Use multimeter TS-352B/U to perform the continuity
cleaning compound, item 1, appendix E.
checks. All tests are made with the controls of the
(3) Use a brush to remove dust or dirt from plugs,
multimeter set as follows:
jacks, and knobs.
FUNCTION ......................... OHMS
b. Fault Isolation Card 1A1A4. Clean the extender
RANGE ............................... RX1
board assembly as required, with inhibisol cleaning
a. Fault Isolation Board 1AlA4 (fig. 6-10).
solvent, or with a solution of 70 percent isopropyl alcohol
(1) Check for short circuits by connecting the
and 30 percent distilled water. Using a brush, clean the
multimeter test leads between the first two etched
printed circuit board contacts with Miller-Stephenson
terminals on one side of the board. Move the two
freon TF degreaser.
multimeter test leads successively, by advancing each
4-9.
Touchup Painting Instructions
test lead one terminal at a time, across the board.
Repeat for the etched terminals on the opposite side of
Remove rust and corrosion from metal surfaces (which
the board. The meter must indicate open circuit for each
have been painted) by lightly sanding them
test.
(2) Check board continuity by progressively
connecting one multimeter test lead to the etched
terminals at one end of the board, while the other
4-2
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