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.
(1) ON-OFF SWITCH (CB1) CONTINUES TO TRIP
Defective: Power source. Circuit breaker CB1.
VOICE OR TTY.
Circuit board A9.
Do not hold ON/OFF switch at ON .
1. Check polarity and voltage to PRIMARY
Proper polarity Go to 2.
POWER connector J8.
and +27 vdc
(refer to TM
2. On the inside of the front panel remove the
L-shaped compartment housing (para
2-9), check CB1 continuity with power