CHART 7-1. Troubleshooting Chart (Cont.).
Check for 6±1 Vdc at terminals
a. If the voltage is low or zero, disconnect the leads
3 and 4 of TB2 in the processor.
from terminals 3 and 4 of TB2 and measure the
voltage at the pc board terminals.
b. If the voltage is still low replace the processor pc
board, reconnect the wires and recheck the voltage.
c. If the voltage is normal with the leads disconnected
check the interconnecting wires for shorts using
procedures in paragraph 7-6.
All transceivers preamplifier outputs are connected
in parallel. Therefore a continuity meter connected
to the leads removed from terminals 3 and 4 of
TB2 should read an open circuit for one polarity
and finite impedance for the opposite
polarity. A low resistance observed for both
polarities indicate a short in the system requiring
sequential disconnection of the transceivers to
isolate the problem.
d. If poor sensitivity still exists at all transceivers
perform the procedure in step 1, procedure b
Poor sensitivity at
Check for 7 to 14 V rms at
a. If the voltage is normal replace the transmit
Terminals 1 and 2 of TB1
transducer (white dot) using procedures in
in the faulty transceiver.
paragraph 7-9. Reset all RANGE controls using
procedures in paragraph 2-18.
b. If the voltage is low, disconnect the leads from
terminals 1 and 2 of TB1 in the transceiver and
measure the voltage at the line.
c. If the voltage is still low, check the interconnecting
wires for a short circuit or low resistance using
procedures in paragraph 7-6.
Check for 6±1 Vdc at
a. If the voltage is normal temporarily substitute a
terminals 3 and 4 of TB1
spare receive transducer (blue dot) and check the
in the transceiver.
transceiver sensitivity. If the receive transducer is
faulty replace it using procedures in paragraph 7-9.
Reset all RANGE controls using procedures in
b. If the voltage is normal and the sensitivity is still
poor replace the transceiver pc board and reset all
RANGE controls using procedures in paragraph
c. If the voltage at terminals 3 and 4 of TB1 is low,
disconnect the leads from these terminals and
check the lines for a short circuit or low
resistance using procedures in paragraph 7-6.
Check the installation for
Perform the noise test in paragraph 2-17b.
alarms during the
open windows or the
protected period or
presence of wildlife with-
system shows high
in the protected area.
" oise"or " alance"
Check the balance voltage
a. If the balance voltage fluctuates excessively the
fluctuation between the
cause is probably extreme levels of air turbulence.
BALANCE test point and
To confirm this symptom temporarily remove the
signal ground using an
leads from the terminals 1 and 2 of TB2 in the
oscilloscope. The voltage
processor. The fluctuations should disappear. To
fluctuations should not be
correct this problem, air flow should be directed
greater than 0.3 volts above
away from the transceiver, eliminated altogether
or below the reference level.
or the transceiver moved to another location or
the RANGE control can be set a lower level.
To identify which transceiver is picking up the
turbulence, set the RANGE control on all units
to 1 and advance the RANGE control on each
unit one at a time to its normal setting.