TROUBLESHOOTING CHART

TM 11-5805-387-34-2

2-6. TROUBLESHOOTING CHART

The troubleshooting chart lists the common malfunctions which you may find during the operation or maintenance

of the modem or its components. You should perform the tests/inspections and corrective actions in the order listed.

Use the troubleshooting chart to localize and isolate trouble. The chart supplements the operational checks,

troubleshooting charts, and PMCS tables in TM 11-5805-387-10-2 and TM 11-5805-387-20-2. Also, the chart is designed

to be used with the foldouts at the back of this manual.

If operational checks or organizational maintenance have designated a defect, find that malfunction in the

symptom index (para 2-5) and go directly to that problem.

The troubleshooting chart Is Indexed by MALFUNCTION/SYMPTOM, for which PROBABLE CAUSES are listed.

Follow the TEST PROCEDURES for which In turn an INDICATION and YES or NO instructions are given.

This manual cannot list all malfunctions that may occur, nor all tests or Inspections and corrective actions. If a

malfunction is not listed or is not corrected by listed corrective actions, notify your supervisor.

MALFUNCTION/SYMPTOM

PROBABLE CAUSE

TEST PROCEDURE

INDICATION

YES

(1) ON-OFF SWITCH (CB1) CONTINUES TO TRIP

Defective: Power source. Circuit breaker CB1.

VOICE OR TTY.

Circuit board A9.

CAUTION

Do not hold ON/OFF switch at ON .

1. Check polarity and voltage to PRIMARY

Proper polarity Go to 2.

Replace

POWER connector J8.

and +27 vdc

defective

power source

(refer to TM

11-5805-387-

10-2).

Do all continuity and resistance checks with all power removed.

2. On the inside of the front panel remove the

Replace

L-shaped compartment housing (para

defective

2-9), check CB1 continuity with power

board A9

CB1 (para

source removed.

2-8