Figure 4-17. Dual Synchronous Rotor
Tachometer Wiring Diagram
(Grounded Two-Wire System)
describe tests and replacement criteria for electrical
resistance temperature indicators.
Continuity check test. Test wiring
for proper continuity as specified in applicable wiring
Master thermometer test. Master
thermometer test Using an electric thermometer tester,
test indicator for proper operation.
ohmmeter or a Wheatstone bridge, test bulbs for proper
indicators or bulbs when proven faulty. Repairs of
damaged wiring shall be per Section VII of TM 55-1500-
Principles of operation and testing of thermocouple
temperature indicators are described in the following
Principles of operation. The thermocouple
temperature indicator consists of an indicator, bulb, and
describe tests and replacement criteria for thermocouple
Resistance test. Disconnect leads
from indicator and test for proper lead resistance with a
Resistance value must be as specified on back side of
indicator. Repair or replace leads when resistance is
other than specified.
Master thermometer test. With on-
lead disconnected, indicator must read within 18° F
(10° C) of surrounding temperature when tested against
a master mercury thermometer. Indicator may be
adjusted to read tolerance with zero adjustment screw.
When indicator cannot be adjusted, it must be replaced.
Outside Air Temperature Gauges. Principles of
operation and testing of outside air temperature gauges,
as shown figure 4-18, are described in the following
Principles of operation. Outside air
temperature gauges show outside air temperature. The
system usually consists of an indicator, bulb, and circuit
describe the test procedures and replacement criteria for
outside air temperature gauges.
Master thermometer test. Test
outside air temperature gauges using the following
Figure 4-18 Outside Air Temperature Gauge