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41
Section 6
Troubleshooting
Symptom Possible
cause
Action
No display even though
measurement key is
pushed
Battery is weak or not
connected.
Check the connections or
replace the battery (see
Inaccurate pH reading
pH calibration is needed
)
Recalibrate the meter.
Cross-contamination from
residual buffers or samples
in sensor cup
Rinse the sensor cup.
Calibration with expired pH
buffers
Recalibrate using fresh
buffers.
No response to pH
changes (MP-6 and MP-6p
models)
Sensor bulb is cracked or an
electromechanical short is
caused by an internal crack.
Replace the pH/ORP sensor
).
Meter does not adjust
down to pH 7 (MP-6 and
MP-6p models)
pH sensor has lost KCl
Clean and restore the sensor
)
and recalibrate. If there is no
improvement, replace the
pH/ORP sensor (see
pH readings drift or
respond slowly to change
or
FAC displays repeatedly
Temporary condition due to
memory of solution in pH
sensor cup for long periods
Clean and restore the sensor
)
and recalibrate. If there is no
improvement, replace the
pH/ORP sensor (refer to
Bulb dirty or dried out
Reference junction clogged
or coated
Unstable conductivity, TDS
or resistivity readings
Dirty electrodes
Clean the cell cup and the
electrodes (see
Minimize the test sample
exposure to air (see
Test samples that are
greater than 1 M
Ω
Meter cannot calibrate
Conductivity or TDS
Film or deposits on
electrodes
Clean the cell cup and the
electrodes (see
Resistivity reading is much
lower than expected
Contamination from previous
samples or from the pH
sensor cup
Rinse the sensor cup more
thoroughly before
measurement.
Make sure the pH cap is
snugly in place
(see
).
Carbon dioxide in the test
sample
Summary of Contents for MP-4
Page 2: ...2 ...
Page 6: ...Table of contents 6 ...
Page 10: ...Specifications 10 ...
Page 30: ...Operation 30 ...
Page 36: ...Calibration 36 ...
Page 42: ...Troubleshooting 42 ...
Page 48: ...Limited Warranty 48 ...
Page 52: ...Conductivity conversion 52 ...
Page 58: ...Additional information on pH and ORP MP 6 and MP 6p models 58 ...