TM 55-4920-328-13
wiring components, check the input thermocouple in the
suspect circuit in accordance with paragraph 5-13. If the
thermocouple is defective, replace the unit and observe
the appropriate meter 4A12M1, 4A12M2, 4A12M3,
4A12M4, or 4A12M7, as applicable, for evidence of a
temperature display. With the thermocouple connected
and suspended in air, the applicable water brake
temperature indicator should indicate approximately
ambient temperature.
b.
If no temperature is indicated in accordance
with step (a), switch the output connections between two
of the temperature transmitters in Unit 11. As an
example, if indicator 4A12M1 displays no temperature
indication, switch the output leads from 11MT15 to
11MT16 and again observe 4A12M1. If the indicator
displays a temperature at or near the correct value, the
trouble is in the temperature transmitter.
c.
If no temperature is indicated after using the
substituting method, check the output of the applicable
power supply in the water brake analyzer panel 4A12.
d.
If output of the temperature transmitter and
power supply is good and no temperature is displayed
on the applicable indicator, the indicator is defective and
must be replaced.
5-26. Air Pressure System.
Troubleshoot the air pressure system as shown in
figure FO-8 and as follows:
NOTE
It is assumed that continuity, voltage levels,
and polarity checks have been made prior to
proceeding with the following.
a.
Check transmitter operation as specified in
paragraph 5-9. Alternately, an operational check of the
system may be conducted by interchanging connectors
11P3 and 11P4. If a pressure is displayed on
temperature and torque/pressure digital indicator 1A1,
the original transmitter is defective and must be
replaced.
b.
With the system energized and an arbitrary
pressure applied to the inlet pressure port of the
transmitter, check for the presence of a dc voltage
between 0 and 5v dc at 1A5J1-y and -z or at 1A5J1-BB
and -CC, depending on the circuit being checked. This
action will indicate that the transmitter analog output is
available.
c.
Check the applicable circuit shown on figure
FO-17 and figure 5-18 to determine power and signal
transmission through the switchling circuits.
d.
Check for the presence of an analog signal at
1A2J7-A and -B. If a signal is observed and no pressure
is displayed, temperature and torque/pressure digital
indicator 1A1 or the interconnecting cable may be
defective.
5-27. Fuel Pressure System.
Troubleshoot the fuel pressure system as shown in
figure FO-9 and as follows:
NOTE
It is assumed that voltage and continuity
checks have been accomplished.
a.
Check transmitter operation as outlined in
paragraph 5-10. Alternately, the substitution method
may be used, as previously explained.
b.
Accomplish checks downstream from the
suspect transmitter following the general sequence of
steps outlined in paragraph 5-26. Check power and
signal circuitry through the switching circuits shown in
figure FO-27.
5-28. Torque Oil Pressure System.
Troubleshoot the torque oil system in accordance
with the circuit information shown in figure FO-11 and as
follows:
NOTE
It is assumed that continuity and excitation
power input checks have been accomplished.
a.
Check the operation of pressure transmitter
11MT5 as outlined in paragraph 5-10.
b.
Accomplish checks downstream from the
transmitter using the general steps outlined in paragraph
5-27. Trace power and signal switching circuits in
accordance with figure FO-27.
5-29. Water Brake Pressure System.
Troubleshoot the water brake pressure system in
accordance with the circuit information shown in figure
FO-12, figure 5-11 and as follows:
NOTE
It is assumed that input power levels and
continuity
have
been
checked
prior
to
proceeding with the following.
5-30
