Symptom Analysis

either the first step in troubleshooting, or use after repairs are completed and before the equipment is returned to the

using organizations.

b. Procedure.

(1) Inspect enclosure for evidence of physical damage.

(2) Inspect terminal strips for cleanliness and evidence of physical damage.

(3) Check all resistors for evidence of discoloration due to overheating.

(4) Inspect all wiring and cabling for worn or frayed insulation, and broken, loose, or disconnected wires or cables.

(5) Inspect all metal surfaces, intended to be painted, for condition of finish and legibility of panel lettering.

NOTE

Touchup paint is recommended instead of refinishing whenever practical

(6) Check the equipment for applicable modification work orders (MWO).

(7) Inspect overall unit for presence of dirt, corrosion, moisture, and bits of wire and solder inside the enclosure.

7-8. Symptom Analysis

Chart 7-1 lists identifiable symptoms to assist the repairman in localizing potential faults.

NOTE

During performance of the symptom analysis when a pc board is replaced in either the processor or the detector, the

SENSITIVITY and GAIN controls must be reset and the tamper circuit checked according to procedures in paragraph 2-

14.

Chart 7-1. Troubleshooting Chart

Step

Symptom

Procedure

Corrective measure

Constant alarm condition

a Check for 20 t 2 Vdc at terminals

a. If voltage is below tolerance disconnected leads

even with all GAIN con-

7 and 8 of TBI (rig.I-1) in the

from terminals 7 and 8 of TBI (fig.1-1) and

trols (fig. 1-1) turned to 1.

processor.

measure the voltage level from the sour

b. If voltage is still below tolerance check inter-

connecting wiring )para 7-6).

c. If voltage is normal replace processor pc board

with a spare and check the equipment in ac-

cording to procedures in paragraph 2-14.

b. Check the tamper switch (fig. 1-1)

Replace the faulty pc board and repeat procedures

using procedures in paragraph

in paragraph 2-14.

2-14a.

a. If the voltage is low or zero, disconnect the leads

Poor sensitivity at all

a. Check for 5.3 .5 Vdc at terminals

from terminals 1 and 2 of TB2 (fig. I1-1) and

detectors.

1 and 2 of TB2 (rig. Processor.

1-1) in the measure the voltage at terminals 1 and

2 of TB2 (fig. 1-1) in the processor.

b. If the voltage is normal (5.3 5 Vdc) check the

interconnecting wires using procedures in para-

graph 7-6.

NOTE

All detector preamplifier outputs are

connected in parallel. Therefore a mul-

timeter connected to the leads removed

from terminals I and 2 of TB2 (fig. 1-1)

should read a finite resistance for one

polarity, and a resistance approximately

9 times higher for the opposite polarity.

A low resistance observed for both po-

larities indicates a short in the system re-

quiring sequential disconnection of the

detector to isolate the problem.

c. If the voltage is still low replace the processor

pc board with a spare one and perform proce-

dures in paragraph 2-14.

7-3