TM1l-6130-381-14
eludes all techniques given for organizational and
c. Localization. Localization procedures should
d i r e c t support maintenance, and any special or
b e performed after the trouble has been sec-
t i o n a l i z e d . The troubleshooting chart (para 6-5)
additional techniques required to isolate a defective
part. If one channel is malfunctioning, check the
s h o u l d be used in localizing the trouble to a
s u s p e c t e d stage. The troubleshooting chart lists
comparable circuits in the other channel if possible.
s y m p t o m s of common t r o u b l e s a n d g i v e ( o r
R e f e r to the component location diagrams of
refererence) corrective measures. Such a chart cannot
include all the trouble symptoms that may occur;
maintenance personnel should use the chart as a
g u i d e in analyzing symptoms that may not be
circuit card assembly of figure FO-3 and the
listed.
wiring harness diagram of figure FO-4 to aid in
CAUTION
fault isolation.
B e f o r e using any ohmmeter to test tran-
6-4. Organization of Troubleshooting Procedures
s i s t o r s or transistor circuits, check the
a. General. Troubleshooting procedures for the
open circuit voltage across the ohmmeter
b a t t e r y charger am contained in paragraphs 6-5
test leads. Do not use the ohmmeter if the
through 6-8. The first step in servicing a defective
o p e n circuit voltage exceeds 1.5 volts.
battery charger is to sectionalize the fault. Sec-
Also, since the RX1 range normally
t i o n a l i z a t i o n means tracing the fault to a major
c o n n e c t s the ohmmeter internal battery
c i r c u i t group of the charger such as the input
d i r e c t l y across the test leads, the com-
power circuit, the battery A or battery B charging
paratively high current (50 mA or more)
v o l t a g e circuit, the battery . A or battery B
may damage the transistor under test. As
charging current control circuit on the battery A or
a general rule, the RS1 range of any ohm-
b a t t e r y B charging voltage-sensing and cutoff
m e t e r should not be used when testing
circuit. The second step is to localize the circuit.
low-powered transistors.
Localization means tracing the fault to a defective
d. Isolation. After the fault has been localized to
stage of the circuit group responsible for the
a stage by using the troubleshooting chart, voltage
a b n o r m a l condition. The third step is isolation.
a n d resistance readings (para 6-7 and 6-8) will
Isolation means locating the defective component
i n d i c a t e a faulty part. The voltage checks will
or part in the circuit stage. Some defective parts,
i s o l a t e the trouble to a group of parts, such as
s u c h as burned resistors and arcing or shorted
resistors, capacitors, and diodes; a resistance check
transformers, can often be located by sight, smell,
will determine which part or component is
and hearing; however, most defective parts must
defective. Waveform data and analysis (para 6-6)
be isolated by checking voltages and resistances.
are also given for the battery charger.
NOTE
i s divided into two identical circuits, one for
When making resistance checks, be careful
battery A and one for battery B. Some circuits,
of the test lead polarity. If the resistance
such as the input power circuit and the frequency
r e a d i n g is low, a l w a y s reverse the test
compensating circuit, are common to both
leads because of the diode action through a
charging circuits. The first step in tracing trouble
t r a n s i s t o r . If a normal resistance is mad
i s to determine the circuit group at fault as
a f t e r the leads are reversed, the stage is
follows
operating correctly.
(1) Visual Inspection. The purpose of visual
If unijunction
e . U n i j u n c t i o n Transistors.
i n s p e c t i o n is to locate faults without testing or
transistor Q6104 or Q6107 is suspected of being
measuring circuits. A l l meter readings, or other
faulty, substitute a known good replacement rather
visual indications, s h o u l d be observed and an
t h a n use the elaborate test setups required to
attempt made to sectionalize the fault to a par-
check them.
f. Test Cab/e. Fabricate a test cable as shown in
ticular circuit group.
(2) Operational Tests. An operational test
D S 0 7 - 7 S - 3 0 6 ) that mates to BATTERY (A) and
frequently indicates the general location of trouble.
BATTERY (B) connectors, and four 12-inch
In many instances, the test will help to determine
lenghts of AWG No. 14 insulated wire terminating
t h e exact nature of the fault. T h e operating
i n alligater clips. Tag each wire with the pin
procedures (para 2-6) with the normally expected
number of the connector it is attached to.
i n d i c a t i o n s called out in the procedures provide
good operational tests.
6-2
