5-5. Checkout of Control Cab Instrumentation.
instrumentation contained in the diagnostic submodule
(Unit 1) and the analyzer sub-module (Unit 2) are
contained in chapter 2. Other instrumentation mounted
in the control cab and depicted in figures FO-2 through
FO-27 may require an isolated type of checkout. These
components are checked as components of a system
during the functional test of that system. Refer to TB
55-4920-328-50 for calibration instructions.
5-6. Checkout of Temperature Transmitters 11MT15
The five temperature transmitters in the water
temperature system, (figure FO-7 located in the back of
this manual), are mounted inside the data acquisition
assembly (Unit 11). These units are identical and are
purposes. Therefore, the substitution method may be
used for troubleshooting at the system level. To
individually check a suspect temperature transmitter, a
dc millivolt source may be used to provide an input
signal to the isolated unit, and a dc milliammeter may
be used to display the output signal. The output range
of each transmitter is from 4 to 20 milliamperes dc full
scale, depending on the magnitude of the input signal.
To check a suspect transmitter by this method, proceed
a. Ensure that all METS electrical systems are
b. Remove the output leads from transmitter 11MT15
(as an example). Tag the leads at removal to facilitate
c. Connect a dc millivolt source (Honeywell Model
2720, or equivalent) to 11J8-A and -B, using iron wire to
connect to pin A and Constantan wire to connect to pin
B. Observe polarity as shown in figure FO-7.
d. Attach the negative terminal of a dc milliammeter
to 11MT5 (+), the positive terminal of the milliammeter
to the positive terminal of a 24v dc power supply, and
the negative terminal of the power supply to 11MT5 (-).
e. Adjust the millivolt source for an output of
approximately +5.00 mv dc. Observe the milliammeter
for an indication of approximately 20 ma dc. If the
indication is approximately as specified, the transmitter
is not defective. If no indication is noted on the
milliammeter, the unit is faulty and must be replaced.
For information on troubleshooting by the substitution
method, refer to paragraph 5-25.
f. If the transmitter was found to be usable, reconnect
the removed wiring, using figure FO-7 as a guide.
Remove the identification tags from the wires. If the
transmitter was found to be defective, install a new
transmitter of like part number. Then functionally check
that portion of the water temperature system as
specified in TB 55-4920-328-50.
5-7. Checkout of Pressure Transmitters 11MT1
Four of the 14 pressure transmitters installed in the
data acquisition assembly (Unit 11) are strain gage type
transmitters and may be functionally checked while
isolated from the respective system. (See table 5-1.)
Each strain gage type of transmitter utilizes 28v dc
excitation power and provides an analog output from 0
to 5v dc. depending on the magnitude of the inlet
pressure. These transmitters are identified on the
respective system schematics at 11MT1 through
11MT4. The other 10 pressure transmitters (11MT5
through 11MT14) are synchronous devices and must be
checked as an integral component of the system.
5-8. Checkout of Strain Gage Type Pressure
Transmitters 11MT1 and 11MT2.
Proceed as follows:
The instrumentation range of 11MT1
and 11MT2 is listed as 0 to 250 psia
in table 5-1. Allowance has been
equipment calibrated in psig in the
following instructions .
a. With all METS electrical systems de-energized,
disconnect connector 11P1 from the mating connector
b. Connect a jumper between 11P1-A and pin A on
the transmitter, and connect a second jumper between
11P1-B and pin B on the transmitter. (This action will
provide 28v dc excitation voltage to the transmitter.)
c. Remove the dust plug from coupler 11M1 on the
data acquisition assembly. (See table 5-1.).