Section III. TROUBLESHOOTING - TM-11-5895-1179-130048

TM 11-5895-1179-13 EE132-EA-OMP-010/E106 KY883 TO 31S1-2GSC-161

Section III. TROUBLESHOOTING

5-4.

General

This section contains the systematic troubleshooting procedure to isolate a fault in the encoder-decoder to a defective

circuit card assembly or discrete part. Most encoder-decoder faults will be quickly isolated by use of the off-line self-test

(paragraph 2-6). When use of the multimeter is required for fault isolation, the required meter indications are shown in the

troubleshooting chart (table 5-1). At the direct support level all subassemblies and discrete parts not located on circuit card

assemblies may be replaced.

Table 5-1. Direct Support Troubleshooting Chart

WARNING

Set ON/OFF switch to OFF before opening front panel assembly and removing circuit card assemblies.

High voltage is present in the power supply even when the ON/OFF switch is OFF. Remove the power

plug and discharge capacitors A7C1 and A5A1Cl to ensure safety.

Item

Checks and

No.

Symptom

Probable Cause

Corrective Action

When ON/OFF

a. Defective power supply

a. Replace power supply

switch is

plug-in-circuit card

set to ON,

assembly A4.

assembly A4

fuse blows.

(paragraph 4-7).

b. Defective diode A7CR4.

b. Replace diode A7CR4

(paragraph 5-26).

c. Defective transformer

c. Replace transformer A7T1

A7T1.

(paragraph 5-11).

d. Defective Backplane

d. Replace Backplane Harness

Harness Assembly A8A5.

Assembly A8A5 (paragraph

5-29).

e. Defective ON/OFF

e. Replace ON/OFF switch

switch assembly A6A4.

assembly A6A4 (paragraph

5-9).

f. Defective bottom panel

f. Replace bottom panel

assembly A7.

assembly A7 (paragraph

5-14).

g. Defective backplane

g. Replace backplane circuit

circuit card assembly

card assembly A5A1

A5A1.

(paragraph 5-14).

h. Defective display and

h. Replace display and con-

control circuit card

trol circuit card assem-

assembly A6A1.

bly A6A1 (paragraph

5-15).

5-2