Emerson Rosemount5081 Instruction Manual page 90

Diagnostics and troubleshooting
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I. T.C. element connections
J. Preamplifier P/N 23561-00
K. Sensor cable connector
Important
Do not connecto anything to outside of preamp BNC connector.
Touch the other end of the second jumper to the center pin of the BNC connector on
the preamplifier.
NOTICE
Do not let the wire touch the outside of the BNC connector.
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.
If a standard millivolt source is available, use it to perform a simulated calibration.
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.
NOTICE
Do not let the wire touch the outside of the BNC connector.
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.
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.
Voltage (mV)
295.8
118.3
-118.3
-295.8
pH
2.00
5.00
9.00
12.00
Rosemount 5081