Chapter 5 Troubleshooting - Emerson Rosemount 389 Instruction Manual

5 Troubleshooting
Table 5-1: Troubleshooting
Trouble
Meter reads off scale (Display reads
overrange).
Display reads between 3 and 6 pH re-
gardless of actual pH of solution or
sample.
Meter or display indication swings or
jumps widely in AUTO T.C. Mode.
Span between buffers extremely short
in AUTO T.C. Mode.
Sluggish or slow meter indication for
real changes in pH level.
Transmitter cannot be standardized.
Transmitter short spans between two
different buffer values.
Instruction Manual
Probable Cause
Defective preamplifier.
T.C. element shorted
Sensor not in process or sample
stream is low.
Open glass electrode.
Reference element open - no contact.
Electrode cracked.
T.C. element shorted.
T.C. element shorted.
Electrode cracked.
Electrode defective.
Electrode coated or cracked.
Defective preamplifier
Old glass electrode or high tempera-
ture exposure.
Coated glass.
Troubleshooting
Remedy
Replace preamplifier (for code 02 sen-
sors). For code 01, replace sensor.
Check T.C. element as instructed in
Section 4.2 and replace sensor if defec-
tive.
Make sure sensor is in process with
sufficient sample stream (refer to
Chapter 2 for installation details).
Replace sensor.
Replace sensor.
Replace sensor.
Check T.Cl. element as instructed in
Section 4.2 and replace sensor if defec-
tive.
Check T.Cl. element as instructed in
Section 4.2 and replace sensor if defec-
tive.
Clean sensor as instructed in
Section 4.1 or Section 4.3.2. Replace
sensor if cracked.
Replace sensor.
Clean sensor as instructed in
Section 4.1 or Section 4.3.2. Replace
sensor if cracked.
Replace preamplifier.
Replace sensor.
Clean sensor as instructed in
Section 4.1 or Section 4.3.2. Replace
sensor if cracked.
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