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236 Micro Motion
®
Series 3000 MVD Transmitters and Controllers
Diagnostics and Troubleshooting
5. Leave the core processor terminal blocks disconnected. At the sensor, remove the lid of the
junction box and test each sensor terminal for a short to case by placing one DMM lead on the
terminal and the other lead on the sensor case. With the DMM set to its highest range, there
should be infinite resistance on each lead. If there is any resistance at all, there is a short to
case.
6. Test terminal pairs as follows:
a. Brown against all other terminals except Red
b. Red against all other terminals except Brown
c. Green against all other terminals except White
d. White against all other terminals except Green
e. Blue against all other terminals except Gray
f. Gray against all other terminals except Blue
g. Orange against all other terminals except Yellow and Violet
h. Yellow against all other terminals except Orange and Violet
i. Violet against all other terminals except Yellow and Orange
Note: D600 sensors and CMF400 sensors with booster amplifiers have different terminal pairs.
Contact Micro Motion customer service for assistance.
There should be infinite resistance for each pair. If there is any resistance at all, there is a short
between terminals. See Table 22-17 for possible causes and solutions.
7. If the problem is not resolved, contact Micro Motion customer service for assistance.
8. To return to normal operation:
a. Plug the terminal blocks into the terminal board.
b. Replace the end-cap on the core processor housing.
c. Replace the lid on the sensor junction box.
Note: When reassembling the meter components, be sure to grease all O-rings.
22.20.2 4-wire remote installation
If you have a 4-wire remote installation:
1. Power down the transmitter.
2. If the transmitter is in a hazardous area, wait five minutes.
3. Remove the core processor lid.
Table 22-17 Sensor and cable short to case possible causes and remedies
Possible cause Solution
Moisture inside the sensor junction box Make sure that the junction box is dry and no corrosion is present.
Liquid or moisture inside the sensor case Contact Micro Motion.
Internally shorted feedthrough (sealed passage
for wiring from sensor to sensor junction box)
Contact Micro Motion.
Faulty cable Replace cable.
Improper wire termination Verify wire terminations inside sensor junction box. See Micro
Motion’s 9-Wire Flowmeter Cable Preparation and Installation Guide
or the sensor manual.