Chapter 6. TROUBLESHOOTING AND REPAIR

TM 11-6625-539-14-3

CHAPTER 6

TROUBLESHOOTING AND REPAIR

6-1. Troubleshooting Techniques

(d) Inspect for loose or missing screws,

specifically those that fasten the rear parts board

a. General. The first procedure in servicing a

in place.

defective test set is to sectionalize the fault, Sec-

(2) Operational tests. Operational tests fre-

tionalization consists of tracing the fault to a

quently indicate the general location of trouble.

group of circuits concerned with one test function.

In many instances, the test will determine the

Once the defective function is found, isolation

exact nature of the fault. The operator's preven-

to the defective part is accomplished. Trouble-

tive maintenance checks and operational check

shooting is performed by general support and

(para 44 ) and the alignment procedures (para

depot repairmen.

71 through 74) provide a good operational

b. Sectionlization. Listed in (1) and (2) be-

test.

low is a group of tests that are arranged to help

(3) Troubleshooting chart and equipment

locate the defect to a faulty component.

required. The meter indications, or lack of meter

indications, and operational checks provide a

(1) Visual inspection. When the test set is

systematic method of localizing trouble to the

brought in for repair, remove the front panel and

faulty circuit. The trouble symptoms listed in the

inspect as follows:

troubleshooting chart (para 62) provide addi-

(a) Check to see that all connections are

tional information for localizing troubles. The

properly seated. Repair or replace any connec-

only test equipment required is Voltmeter, Elec-

tions or leads that are broken or otherwise de-

tronic ME-30(*)/U (TM 11-6625-320-12).

fective.

(b) Check all switches and controls for

NOTE

ease of operation.

Voltmeter, Electronic ME-30(*)/U re-

p r e s e n t s Voltmeter, Meter ME-30A/U

teries, and check for corrosion and looseness of

and Voltmeters, Electronic ME30B/U

batteries.

and ME30E/U.

6-2. Troubleshooting Chart

Symptom

Probable cause

Corrective measure

Meter pointer does not fall within BAT

Batteries loose or weak. Meter Ml

Check batteries (fig. 6-1). Check meter

position on scale with function switch

defective.

Ml.

on BAT.

Meter pointer does not align (para 7-2)

VR1, R10, R11, or R13 defective . . Check VR1, R10, R11, and R13.

ME-30 (· )/U does not indicate 100 mv

Q1, Q2, Q3, or T1, or associated cir- Check Q1, Q2, Q3, T1, and associated

(para 7-3).

cuitry defective (fig. 5-6 and 7-1).

circuitry.

Meter pointer does not indicate full

Q4, Q5, Q6, CR1, CR2, CR3, CR4, Check Q4, Q5, Q6, and CR1 through

scale (para 7-3).

or associated circuitry defective.

CR4.

6-1