relative indications observed, possible causes, suggested checks and /or tests to verify the causes, and
suggested corrective action or repair procedures.
3-90. This section contains troubleshooting instructions applicable
to all intemediate maintenance
activities. Where procedures are applicable to both echelons, no notation is included.
3-91. Troubleshooting, as it applies to intermediate Maintenance activities, consists of the procedures
described in paragraphs 3-11 through 3-71 plus detail testing and replacement of modules, assemblies,
pcb/pwb circuits and components.
3-92. LOGICAL APPROACHES
TO POWER AMPLIFIER TROUBLESHOOTING
3-93. The following six logical steps should be followed when troubleshooting the power amplifier:
1. Symptom Recognition. Symptom recognition is based on knowledge and understanding of equip-
ment operating characteristics. Not all equipment troubles are a direct result of component failure; there-
fore a malfunction in the equipment is not always easy to recognize, since conditions of less than peak
performance are not always apparent.
2. Symptom Elaboration. After an equipment trouble has been recognized, use of system front panel
and other built-in testing aids (such as test
controls (refer to chapter 3 of TM 11-5820-924-12)
meters, test points and LED indicators) are recommended to assist in the verification of the original symptom
(and also to eliminate possible malfunctions in other equipment as the cause).
3. Listing Probable Faults or Malfunctions. The next step in logical troubleshooting is to list the logical
causes and their likely locations (module, pcb/pwb, or functional section). The causes should be based on
knowledge of equipment operation, identification of trouble symptoms, and information contained in
4. Localizing the Sources of Faults or Malfunctions. For best efficiency in localizing the trouble, the
logical causes should be checked in the order that will require the least time; therefore, a selection is
required to determine which section to test first. The selection should be based on the validity of the
logical choice, and the difficulties involved in making the necessary tests (some of which may be outside the
scope of intermediate maintenance). If the tests do not prove that a functional section is at fault, the next
selection should be tested, and so on, until the faulty functional section is located.
5. Localizing Faults or Malfunctions to a Particular Circuit. After the faulty functional module,
pcb/pwb, or major assembly has been isolated, it is often necessary to make additional logical choices as
to which circuit(s) within the functional section is at fault. Again, familiarity with the equipment and an
understanding of the functional operation as explained in chapter 2 of this manual, is important.
6. Fault/Malfunction Analysis. After the trouble (faulty component, misalignment, etc.) has been
located, but prior to corrective action, the procedures followed up to this point should be reviewed to
determine why the fault affected the equipment as it did. This review is necessary to make sure that the
fault discovered is actually the cause of the malfunction and not a result of it.
3-94. TROUBLESHOOTING INDEX
3-95. Table 3-7 is the power amplifier troubleshooting index. The table lists the major functional areas
where troubles may occur, and references troubleshooting procedures, diagrams, and functional
3-96. RELAY, INDICATOR LAMP, AND CIRCUIT BREAKER INDEXES
3-97. Tables 3-8, 3-9 and 3-10 list trouble analysis references for relays, indicators, lamps, and circuit
breakers in the power amplifier.