Emerson Rosemount 148, Reference Manual, Page: 32 / 36

4.2.1 Maintenance
Sensor checkout
To determine whether the sensor is at fault, replace it with another sensor or connect a
test sensor locally at the transmitter to test remote sensor wiring. Do not remove the
thermowell while in operation. Select any standard, off-the-shelf sensor for use with a
Rosemount 148 Tramsmitter or consult the factory for a special replacement sensor and
transmitter combination.
4.2.2 Diagnostic messages
If a malfunction is suspected, follow the procedures described in Table 4-1 to verify that
transmitter hardware and process connections are in good working order. Under each of
the three major symptoms, specific suggestions are offered for solving the problem.
Table 4-1: Rosemount 148 Troubleshooting Chart
Symptom Potential source Corrective action
High output
Sensor input failure or
connection • Check for a sensor open or short
circuit.
• Check the process variable to see if it is
out of range.
Loop wiring • Check for dirty or defective terminals,
interconnecting pins, or receptacles.
Power supply • Check the output voltage of the power
supply at the transmitter terminals. It
should be 12.0–42.4 Vdc (over entire
3.75–23 mA operating range).
Erratic output Loop wiring • Check for adequate voltage to the
transmitter. It should be 12.0–42.4
Vdc at the transmitter terminals (over
entire 3.75–23 mA operating range).
• Check for intermittent shorts, open
circuits, and multiple grounds.
Low output or no
output Sensor element • Check the process variable to see if it is
out of range.
Operation and Maintenance Reference Manual
June 2019 00809-0100-4148
32 www.Emerson.com