Maintenance 39
Symptoms Problems Solution
No sensor connection.
Sensor model not
recognized.
Make certain, 3 mm connector is in all
the way by pushing rmly into probe
input.
Slow response/excessive
drift.
Dirty pH electrode.
Clean the electrode and then soak
the tip in HI 7061 or HI 8061 for 30
minutes.
Readings uctuate up
and down (noise).
pH: Clogged/dirty
junction. Low electrolyte
level (re llable
electrodes only).
Clean the electrode. Re ll with fresh
solution (for re llable electrodes only).
Check cable and connectors.
The meter does not
accept the bu er/
standard solution for
calibration.
pH: Dirty electrode or
contaminated bu er.
Follow the cleaning procedure. If still
no results, replace the electrode.
Replace bu er.
If the display shows: “pH”
and “-2.00” or “16.00”
blinking.
Out of range in the pH
scale.
A) Verify that the shipping cap has
been removed.
B) Make sure the pH sample is in the
speci ed range.
C) Check electrolyte level and general
state of the electrode.
If the display shows:
“mV” and “-1000” or
“1000” blinking.
Out of range in the mV
scale.
A) Verify the shipping cap has been
removed.
B) Make sure the sample pH is within
speci ed range.
C) Verify electrolyte level in pH sensor
is topped o .
D) Verify no bubbles inside pH
membrane.
The meter does not
measure temperature.
“----” is displayed on
second LCD line.
Broken temperature
sensor.
Replace the probe.
The meter fails to
calibrate or gives faulty
readings.
Broken pH electrode. Replace the electrode.
At startup the meter
displays all LCD tags
permanently.
One of the keys is stuck.
Check the keyboard or contact your
local Hanna O ce.
CAL “Prod” message at
startup.
Instrument was not
factory calibrated or lost
factory calibration.
Contact Hanna Technical Support for
help.
Troubleshooting
Guide
After performing any of the cleaning procedures, rinse the electrode thoroughly
with distilled water, and re ll the reference chamber with fresh electrolyte (not
necessary for gel-filled electrodes) and soak the electrode in HI 70300 or
HI 80300 Storage Solution for at least 1 hour before taking measurements.
Temperature dependence for ORP sensors
The oxidation-reduction potential (ORP) displayed in mV, is the voltage that
results from the di erence in potential between the platinum metal surface and
the Ag/AgCl reference electrode. ORP values are not temperature compensated,
although ORP mV can change with temperature (e.g. reference electrode potential
changes and sample equilibrium changes). It is important to report ORP values
together with the reference electrode used and the temperature of measurement.
ORP Probe
Maintenance
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