Troubleshooting Guide; Troubleshooting; Stray Light - LaMotte 2020t/i Mode D'emploi

consistent. Use the last consistent reading to calibrate the meter. If the readings are
not consistent, avoid using an aberrant reading to calibrate the meter.
18. Calibrate the meter daily.
19. Calibrate the meter with a standard that is closest to the expected range of the
sample being tested. For example, if the sample is expected to be less than 1.0
NTU, calibrate with a 1.0 NTU standard and a blank (0 NTU standard). If the sample
is expected to be around 2 NTU also calibrate with the 1.0 NTU standard but if the
sample is expected to be around 8 NTU calibrate with a 10 NTU standard. If the
sample is expected to be over 30 – 40 NTU it is recommended that the meter be
calibrated with a 100 NTU standard.
20. To maintain a consistent lamp temperature, do not turn the meter on and off when
analyzing samples.

TROUBLESHOOTING GUIDE

 TROUBLESHOOTING
PROBLEM
"Blank?"
Flashing
"Low Battery"
"Shut Down Low Batt"
Shut Down
"Over range"
"Error1"
Unusually large negative
or positive readings when
performing calibration
 STRAY LIGHT
The accuracy of readings on the 2020t/i should not be aff ected by stray light. Make
sure that the sample compartment lid is always fully closed when taking readings. The
backlight will interfere with turbidity readings. The meter will temporarily disable the
backlight while turbidity measurements are being taken.
REASON
Sample is reading lower
than the blank.
Low battery. Readings are
reliable.
Battery voltage is very low.
Readings are not reliable.
Battery is too low to
operate the unit.
Sample is outside of
acceptable range.
High readings with 90° and
180° detectors.
Incorrect standards used to
calibrate meter.
39
SOLUTION
With samples of very low
concentration reblank or
record as zero. On samples of
higher concentration reblank
and read again.
Charge battery or use USB
wall/computer charger.
Charge battery or use USB
wall/computer charger.
Charge battery or use USB
wall/computer charger.
Dilute sample and test again.
Dilute sample by at least 50%
and retest.
Use fresh 0.0 standard in
clean tube. Recalibrate meter.