TM 11-6625-2398-15-2
Sequence
Item
Procedure
References
No.
c. Extender boards for proper seating in IFF set printed
circuit board connectors.
d. Printed circuit board extractors for proper mating in
time holes of printed circuit board.
a. TB 11-6625-2398-35
6
Calibration
a. Check insertion loss of hybrid attenuator 2A1.
b. Check VSWR of hybrid attenuator 2A1.
b. TB 11-6625-2398-35
c. Check insertion loss of cables 1A2W4 through
c. TB 11-6625-2398-35
1A2W7 and 2W7 / 2W8
Troubleshooting the cables and extender boards of the
4-8. Cleaning.
test facilities set consists of continuity checks with a
a. Transit Cases 1A1/ 2MP1, and Accessory Case
multimeter (par 4-12). The schematic diagrams in
2A2. Inspect the exterior surfaces of the transit cases
and accessory case. The exterior surfaces should be
connections to check for continuity. Any cable found to
clean, free of dust, dirt and grease.
be defective should be sent to higher category of
maintenance for repair.
(1) Remove dust and loose dirt with a clean,
lint free cloth.
4-11. Operator's Repairs and Adjustments
WARNING
a. Minor Repair of Cables Repair minor cuts in
Cleaning compound is flammable and
cable insulation by covering it first with rubber tape, and
its fumes are toxic. Provide adequate
then with friction tape. If a cable is ,broken, ship
ventilation. DO NOT use near a
defective cable to higher category of maintenance for
flame.
repair.
(2) Remove grease, and ground-in dirt from
b. Replacement and Calibration of Knobs.
the components. Use a cloth dampened (not wet) with
cleaning compound.
(1) Replacement. To replace a defective
(3) Use a brush to remove dust or dirt from k
knob, proceed as follows:
plugs. jacks, and knobs.
(a) Set the knob to its extreme counter clockwise
b. Extender Cards 1A1A3/ 1A1A4.
and 2A4.
position.
periodically clean the extender board assemblies with
(b) Loosen setscrews on the defective knob and
inhibisol cleaning solvent, or with a solution of a 70
remove the knob from the shaft.
percent isopropyl alcohol and 30 percent distilled water.
(c) Place a new knob on the shaft, and line up the
Using a brush, clean the printed circuit board contact
zero position on the new knob with the zero index on the
with Miller-Stephenson freon TF degreaser.
associated panel.
(d) Tighten setscrews.
4-9. Touchup Painting Instructions
(2) Calibration. To calibrate a knob on its shaft.
Remove rust and corrosion from metal surfaces S (which
proceed as follows: (a) Tighten the setscrews on the
have been painted) by lightly sanding them with fine
loose knob and turn it to its extreme counterclockwise
sandpaper. Brush two thin coats of paint a on the bare
stop.
metal to protect it from further corrosion. Refer to
(b) Loosen setscrews and line up the zero position
applicable cleaning and refinishing practices specified in
of the knob with the zero index on the associated panel.
TB -746-10. For touchup painting of the transit cases
(c) Tighten setscrews.
and the accessory case use light gray enamel, formula
no. 11 (per MIL-E4 15090), type II, class 1 (gloss). For
4-12. Continuity Check of Cables and Extender
touchup painting of the hybrid attenuator and the
interface 1 adapter unit use light gray enamel, formula
continuity checks. All tests are made with the controls of
No. 11 (per MIL-E-15090), type II, class 2 (semigloss).
the multimeter set as follows:
FUNCTION ............................... OHMS.
4-10. General Troubleshooting Information
RANGE ..................................... RX 1.
Troubleshooting this equipment is based upon the
a. Extender Boards 1A1A3/1A1A4 and 2A4.
operation of the test facilities set ill a test-bed
configuration with the IFF set If. in troubleshooting the
(1 ) Check for short circuits by connecting the multimeter
IFF set, certain components of the test facilities set are
test leads between the first two etched terminals on one
defective, or suspected of being defective (other than
side of the board. Move the two multimeter test leads
cables, extender boards or the interface adapter unit),
successively. by advancing each test lead one terminal
higher category of maintenance is required.
at a time, across the board
4-3
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