Emerson Rosemount5081, Instruction Manual, Page: 77 / 152

4. if the transmitter responds to simulated inputs, the problem must lie with the
sensor or the interconnecting wiring. Verify the interconnecting wiring point to
point. Fix or replace bad cable. If cable is good, replace the pH sensor.
Std Err
Std Err means the reference electrode voltage has changed drastically. Typical causes are
exposure to poisoning agents, sulfides or cyanides, or prolonged exposure to high
temperature.
Flowchart-Std Err
Troubleshooting depends on the type of sensor.
• If the sensor is rebuildable, replenish the electrolyte solution and replace the liquid
junction. Calibrate the sensor.
- If the sensor can be calibrated, the problem has been corrected.
- If the sensor cannot be calibrated, replace the sensor. If the sensor has separate
measuring and reference electrodes, replace only the reference electrode.
• If the sensor is not rebuildable, try the reference electrode rejuvenation procedure.
- If the rejuvenated sensor can be calibrated, the problem has been corrected.
- If the sensor cannot be calibrated, replace the sensor.
rOM FAIL or CPU FAIL
rOM FAIL or CPU FAIL means the transmitter electronics have failed. Replace the electronic
board stack (PN 23992-02 [-HT] or PN 23992-03 [-HF]).
AdC WArn or CyCLE PWr
The Adc WArn or CyCLE PWr message appears momentarily when the transmitter has
recognized an internal calculation problem. The transmitter repeats the calculation, and
the message disappears once the calculation is successful. If the message is displayed
constantly, the transmitter electronics may be faulty.
Troubleshooting AdCWArn or CyCLE PWr
1. Check transmitter performance by simulating pH inputs. See Section 8.1.7 .
• If the transmitter performs satisfactorily, go to Step 2.
• If the transmitter does not respond to simulated inputs, replace the board stack.
2. If the transmitter responds to simulated inputs, the problem must lie with the
sensor or the interconnecting wiring. Verify the interconnecting wiring point to
point. Fix or replace bad cable. If cable is good, replace the pH sensor.
WritE Err
WriTE Err means that jumper JP1 on the CPU board is not in place. If the sensor is not in
place, the transmitter cannot be programmed or calibrated.
Diagnostics and troubleshooting
Instruction Manual 67