TM 11-6130-413-40
Section II. TROUBLESHOOTING
3-3. Maintenance Procedures
mentary short circuit can damage a transistor. (For ex-
a. General. The first step in servicing is to observe
ample, if the bias resistor of a transistor is shorted out,
the operation of the equipment and note what opera-
excessive current between the emitter and the base
tions can and cannot be accomplished. This will help to
could damage the transistor.)
localize the trouble to a particular component or group
e. Troubleshooting Procedures. The troubleshooting
of components. The second step is to isolate the fault,
procedures (para 3-6) are based on symptoms of
which means tracing the fault to a defective part re-
trouble and recommended procedures that will aid in
sponsible for the abnormal operation. Some faults,
localizing and finally isolating the trouble. Mainte-
such as broken circuit board wiring, or wires that con-
nance of the equipment is limited to replacement of as-
nect between controls, switches, or cable assemblies
semblies and components based on observation of ab-
can often be located by sight. The majority of the
normal operating conditions, or inability of the unit to
faults, however, must be isolated by continuity checks
comply with the performance standards.
and component substitution.
f. Intermittent Troubles. In all these tests, the pos-
b. Visual Inspection. The purpose of visual inspec-
sibility of intermittent troubles should not be over-
tion is to locate faults without testing or measuring
looked. If present, this type of trouble maybe made to
circuits. All visual signs should be observed and an at-
reappear by tapping or jarring the equipment. Check
tempt made to localize the fault to a particular area or
the internal wiring and connections for looseness.
isolate it to a particular component. Visual inspection
of the equipment often points out areas of trouble. If
for simple electrical measurements. When using the
any of the conditions listed below appear, effort
ohmmeter portion of the multimeter (or any ohm-
should be directed to make the necessary repairs. The
meter), disconnect power and observe the following
following are some suggested general items:
caution.
(1) Check that all internal wiring connections are
CAUTION
properly secured and insulated.
As a general rule, it is not recommended
(2) Check that all grounding connections are prop-
that the RX1 range of any ohmmeter be used
erly and securely made.
when testing transistors. The RXl range on
(3) Inspect connectors, receptacles, jacks, and
most ohmmeters normally connects an in-
plugs for broken, worn, or warped contact surfaces.
ternal 1.5 volt battery directly across the
(4) Check for proper termination of all external
test leads, causing comparatively high cur-
cables.
rent (50 milliamperes or more) to flow which
(5) Inspect all parts for evidence of overheating
may damage the transistor under test. Be-
caused by short circuits or leakage paths. Discoloration
fore using any ohmmeter to test transistor
and sometimes accompanying odors of burning compo-
circuits, check the open-circuit voltage
nents and wiring insulation indicate excessive heat has
across the ohmmeter test leads for each
been generated. Damage from overheating is usually a
meter range.
symptom of less obvious trouble; and unless the cause
3-4. Operational Checkout Procedures
is determined before parts are replaced, the damage
may be repeated.
These procedures may also be used to check out unit
c. Testing Procedures. After any repair of the equip-
operation after installation, servicing, or as a periodic
ment always test it for satisfactory performance be-
operational check of the equipment. If a known good
fore returning the equipment to the user or placing it
battery is used for test, the operational steps and panel
in repair stock. Refer to paragraphs 3-4 and 3-5 for
indications should follow this procedure. Connect dc
operational checkout and testing procedures, respec-
output connector J5 to the known good battery, con-
tively, Note that these procedures are also useful for
nect ac connector P3 to the local ac power source, then
checking equipment performance prior to trouble-
perform the following procedures:
shooting as an aid to general location.
CAUTION
CAUTION
Do not block or restrict air flow through case
Portions of this equipment are transisto-
screens.
rized; make voltage measurements only as
a. Phase 1--Capacity Test (Initial Discharge)- Pro-
specified in the voltage and resistance chart
ceed as follows:
(1) Set ON-OFF switch (CB1) to OFF position.
(2) Set CELL SELECT switch (S6) to correspond
with number of cells in battery connected to unit.
uring voltages, use tape or sleeving to insulate the en-
(3) Rotate AUTO-CHARGE NO. 1 timer (M3)
tire test prod, except for the extreme tip. A mo-
3-2
