Service manual

STP 11-25R13-SM-TG
3 - 16
PERFORM CABLE MAINTENANCE
113-588-3022
Conditions: In a tactical or garrison environment, you are experiencing technical difficulties with a signal
and suspect faulty cables. Given a system with installed audio and video cables, soft dry cloth, block
diagrams, multimeter with test leads, crimping tools, electronic equipment tool kit, third-hand type vise,
soldering tool kit (light to medium duty), heat gun, heat shrink, electrical tape, bench stock (of various
connectors, wire, and cable), DA Form 2407, and DA Pam 738-750.
Standards: The standards are met when cables are correctly identified as good, open, or shorted, and
defective cable(s) or connector(s) are replaced or repaired as necessary.
Performance Measures Results
1. Refer to system block diagrams to localize the problem. P F
2. Isolate the problem to a suspected cable by checking equipment in the system at
different stages using available test and monitoring equipment (monitors, speakers,
switchers, patch panels, and meters).
P F
3. Visually inspect cable for cuts, broken connectors, missing or bent pins, and other
obvious damage.
P F
4. Disconnect cable and perform resistance continuity tests with a multimeter. P F
a. Conductor to the same conductor (on the opposite end of the cable) should read
some resistance.
P F
b. Conductor to another conductor should read as an open circuit, infinity. P F
5. Substitute defective cable with a known good cable, or repair or replace the connector. P F
a. Wire 3-pin XLR connectors as follows: P F
(1) Red or white (high) to pin 2. P F
(2) Black (low) to pin 3. P F
(3) Shield (ground) to pin 1. P F
b. Wire phone plugs and jacks as follows: P F
(1) Red or white (high) to Tip. P F
(2) Black (low) to Ring. P F
(3) Shield (ground) to Sleeve. P F
c. Wire audio three conductor connections as follows: P F
(1) Red (high) to pin 2. P F
(2) Black (low) to pin 3. P F
(3) White (signal ground) to pin 1. P F
NOTE: Do not connect (N/C) shield (ground shell drain). Do not connect either the white or
shield to any ground except through the terminals specified for this purpose.
d. Wire RCA-style phono plugs as follows: P F
(1) Red or white (high) to the center pin. P F
(2) Black (low) to N/C. P F
(3) Shield (ground) to the shell. P F
e. Transformer isolates all unbalanced lines. Drive unbalanced lines from one side
of a balanced output driver; do not connect the other side. This configuration
typically results in a 6 dB level loss.
P F
6. Test cable continuity with a multimeter. P F
7. Install and connect replaced or repaired cable in the system. P F
8. Verify that no further problem exists. P F
9. Complete a DA Form 2407 to account for work accomplished. P F