either the first step in troubleshooting, or use after repairs are completed and before the equipment is returned to the
(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.
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.
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-
Chart 7-1. Troubleshooting Chart
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.
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
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
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-
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.