15.32 Check for internal electrical problems
Shorts between sensor terminals or between the sensor terminals and the sensor case can cause the sensor to
stop working.
Possible cause
Recommended action
Liquid or moisture inside the sensor case
Contact customer support.
Internally shorted feedthrough
Contact customer support.
Faulty cable
Replace the cable.
15.32.1 Check the sensor coils
Checking the sensor coils can identify a cause for a no sensor response alert.
Restriction
This procedure applies only to 9-wire remote-mount transmitters.
Procedure
1. Disconnect power to the transmitter.
CAUTION
If the transmitter is in a hazardous area, wait 5 minutes before continuing.
2. Unplug the terminal blocks from the terminal board on the core processor.
3. Using a digital multimeter (DMM), check the pickoff coils by placing the DMM leads on the unplugged
terminal blocks for each terminal pair. See
for a list of the coils. Record the values.
Table 15-5: Coils and test terminal pairs
Coil
Sensor model
Terminal colors
Drive coil
All
Brown to red
Left pickoff coil (LPO)
All
Green to white
Right pickoff coil (RPO)
All
Blue to gray
Resistance temperature detector
(RTD)
All
Yellow to violet
Lead length compensator (LLC)
All except T-Series and CMF400 (see
note)
Yellow to orange
Composite RTD
CMFS025-150 and T-Series
Yellow to orange
Fixed resistor (see note)
CMFS007, CMFS010, CMFS015,
CMF400, and F300
Yellow to orange
Note
The CMF400 fixed resistor applies only to certain specific CMF400 releases. Contact customer support
for more information.
There should be no open circuits, that is, no infinite resistance readings. The left pickoff and right
pickoff readings should be the same or very close (±5 Ω). If there are any unusual readings, repeat the
Troubleshooting
Configuration and Use Manual
April 2019
MMI-20048166
202
Micro Motion 4200 Transmitters