Organization of Troubleshooting Procedures

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

f i g u r e s 5-1 through 5-3, schematic diagram of

include all the trouble symptoms that may occur;

f i g u r e FO-1, the color code diagram of figure

maintenance personnel should use the chart as a

F O - 2 , the parts location diagram of the control

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.

b. Sectionalization. The battery charger circuitry

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

figure 6-1. Use a female connector (Deutsch Model

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