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MODEL 3081 pH/ORP SECTION 12.0
TROUBLESHOOTING
Process pH measurement
problem
Perform buffer calibration
(outside of the process)
Refer to Section 7.5
Buffer calibration
OK?
Preamplifier and trans-
mitter test OK?
Put transmitter preamplifier switch
(S-1) into junction box position.
Likely Process Problem
or Ground Loop:
1. Measure pH of a grab sample in
a beaker. If pH is correct, then
the process is OK.
2. Resolve the ground loop; insu-
late shield wires from grounded
metal. See Section 12.5.8
3. Ground un-grounded processes:
(example: all plastic piping)
Likely Sensor Problem:
1. Verify sensor is compatible with
the analyzer. Must have PT100,
PT1000, or 3K Balco RTD. Verify
RTD jumpers and temperature
parameter programming.
2. Check RTD. If bad or wrong, use
manual temperature compensa-
tion (see Section 8.5).
2. Clean sensor & re-test it.
3. If problem persists, rebuild or
replace the sensor.
Simulate pH directly into
transmitter: bypass the pre-
amplifier. See Section 12.8.2.
Simulate pH through the pream-
plifier and transmitter. Refer to
Section 12.8.3.
YES
YES
YES
YES
NO
NO
NO
NO
Is transmitter
preamplifier switch in
junction box position?
(see Figure 2-2)
Preamp or Wiring problem:
1. Check wiring.
2. Replace preamplifier.
Transmitter problem:
1. Replace Analog/CPU board stack
(PN 23574-02)
Transmitter test OK?
FIGURE 12-5. Troubleshooting Flow Chart / Preamplifier in Sensor-Mounted Junction Box
or Remote Junction Box