TM 11-6110--211-15
CHAPTER 3
TROUBLESHOOTING AND REPAIR
Section I. GENERAL PROCEDURES
on the voltage and resistance diagrams (fig. 3-1
3-1. GeneraI
and 3-2). Use the ohmmeter range specified on
The organizational and direct and general sup-
the diagrams, otherwise, the indications obtained
port maintenance procedures in this manual sup-
will be inaccurate.
plement the troubleshooting procedure described
Caution: Before using any ohmmeter to test
in the technical manuals covering the aircraft in
transistors or transistor circuits, check the
which the AM-3209/ASN is installed. The sys-
open-circuit voltage across the ohmmeter test
tematic troubleshooting procedure, which begins
leads. To prevent damage to the transistors
with the system and sectionalization checks that
because of excessive current drain, do not use
can be performed in the aircraft, is carried to a
the ohmmeter if the open-circuit voltage ex-
higher level in this manual. Troubleshooting and
ceeds 1.5 volts. Also, since the Rx1 range
repair instructions contained within this manual
normally connects the ohmmeter internal bat-
are limited to the AM-3209/ASN; instructions
tery directly across the test leads, the compara-
relative to the application of the AM-3209/ASN
tively high current (50 milliamperes (ma) or
in a complete navigation system will be found in
more) may damage the transistor under test.
the technical manual covering the aircraft in
As a general rule, it is not recommended that
which the AM-3209/ASN is installed.
the Rx1 range of any ohmmeter be used when
3-2. General Troubleshooting Instructions
testing transistors.
General instructions arranged to reduce unnec-
d. Intermittent Troubles. In all of the tests,
essary work arid to aid in tracing trouble to a de-
the possibility of intermittent troubles should not
fective component are given below.
be overlooked. If present, this type of trouble
a. Visual. Inspection. The purpose of visual
often may be made to appear by tapping or jarring
inspection is to locate faults without testing or
the AM-3209/ASN. Make a visual inspection of
measuring circuits. All voltage and resistance
the wiring and connections at the base of the circuit
readings should be observed. A thorough and
boards and connector. Minute cracks in the circuit
searching visual inspection of the internal com-
board can cause intermittent operation. A mag-
ponents should also be made to detect failures.
nifying glass is often useful in locating defects in
b. Voltage Measurements. This equipment is
printed boards.
Continuity measurements of
transistorized. When measuring voltages, use tape
printed conductors may be made by the use of the
or sleeving (spaghetti) to insulate the entire test
same technique ordinarily used on hidden conven-
prod, except for the extreme tip. A momentary
tional wiring; observe ohmmeter precautions dis-
short circuit can ruin the transistor. Use the same
cussed in c above.
or equivalent electronic voltmeter specified in
e. Resistor and Capacitor Color Code Diagrams.
The resistor and capacitor color code diagrams
diagrams (fig. 3-1 and 3-2).
determining the value, voltage rating, and toler-
ance of capacitors and resistors.
measurements in this equipment only as directed
Section Il. TROUBLESHOOTING INFORMATION
the troubleshooting chart is based on the symptoms
3-3. Troubleshooting Procedures
obtained when the AM-3209/ASN is connected
Operation failure and malfunctioning of the
into a complete servo loop system consisting of a
AM-3209/ASN are listed in the troubleshooting
chart (para. 3-5). The information provided in
signal source and the motor-generator and warn-
3-1
