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MODEL 3081 pH/ORP SECTION 12.0
TROUBLESHOOTING
10. Touch the other end of the second jumper to the center pin of the BNC connector on the preamplifier. DO NOT LET
THE WIRE TOUCH THE OUTSIDE OF THE BNC CONNECTOR.
11. Measure the voltage. The measured voltage should be 0 mV, and the pH should be approximately 7. Because the
calibration data in the transmitter may be offsetting the input voltage, the displayed pH may not be exactly 7.0. If the
actual readings are close to expected, the transmitter is probably working fine.
12. If a standard millivolt source is available, use it to perform a simulated calibration.
13. Remove the jumper used to connect the reference pin to the center pin of the BNC. Connect the negative terminal of
the standard millivolt source to the reference pin and connect the positive terminal to the center pin of the BNC. DO
NOT LET THE WIRE TOUCH THE OUTSIDE OF THE BNC CONNECTOR.
14. Following the auto calibration procedure in Section 7.5, calibrate the transmitter. Use 0.0 mV for pH 7 (bF1) and
-177.4 mV for pH 10 (bF2). If the transmitter is working, it should accept the calibration.
15. To check linearity, leave autocalibration and return to the main display. Set the voltage source to the values in the
table and verify that the pH reading matches the expected value.
12.8.5 pH Simulation When Preamplifier is in Sensor
The preamplifier in the sensor simply converts the high impedence signal into a low impedance signal without amplifying
it. To simulate pH values, use the procedure in Section 12.8.3.
12.9 FACTORY ASSISTANCE AND REPAIRS
12.9.1 Troubleshooting Assistance.
For assistance in correcting transmitter, sensor, and measurement problems...
- in the United States call Rosemount Analytical Uniloc Division at (800) 854-8527.
- outside the United States call the nearest Fisher-Rosemount office. See the back page of the manual.
12.9.2 Return of Materials
If it is necessary to return the transmitter to the factory for repairs...
- in the United States call Rosemount Analytical Uniloc Division at (800) 854-8527.
- outside the United States call the nearest Fisher-Rosemount office. See the back page of the manual.
Always call before returning material. Do not send anything without obtaining a Return Material Authorization
(RMA) number.
Voltage (mV) pH
295.8 2.00
118.3 5.00
-118.3 9.00
-295.8 12.00