LaMotte TC-3000 Troubleshooting Manual

TC-3000 Meter Troubleshooting Guide

Negative Results

The 2020e and 2020i turbidity meters will display
negative results if the sample water is less turbid
than the blank reading. This is possible in ultra­low turbidity waters, where the sample turbidity is
at or near the detection limit of the meter.

Negative readings can also indicate a problem
when the meter was blanked. If the meter is
accidentally blanked to a 1.0NTU standard,
subsequent tests may negative, in response to
the high blank reading. Correct this problem as
follows:

1. Reset the meter to the factory calibration
settings: with the meter turned OFF, hold down the
*OK button and press ON. Release both buttons
at the same time. Press *OK to select the default
settings. Press *OK again and the meter will turn
off. The factory settings will be restored.

2. Follow the instructions on how to properly fill
the turbidity tubes with the standard solutions (see
below).

3. Once the tubes are filled with standard, turn
the turbidity meter on and enter the measurement
mode. Scan the blank tube (0.00 NTU). Then
leave the blank tube in the meter and press *OK to
scan the blank as a sample. It should read 0.00.
If not, press the UP button and reblank the meter
again. Then scan the blank as a sample again
until it reads 0.00. This may take at least three
tries.

NOTE: a small negative number will be observed
if the reading is slightly less than the reading
used as a blank. This is expected due to minute
variations between readings. A reading of -0.02 or
even -0.04NTU is not uncommon. Once 0.00 or a
very small negative number is achieved, the meter
is ready to be calibrated.

Filling Turbidity Tubes

It is important to use the proper test tube designed
for use with the 2020e and 2020i turbidity meters,
LaMotte code 0475. Tubes must be clean and free
from fingerprints, lint, dried spills and significant
scratches. Use lint free tissue to wipe your tubes
clean.

When filling a tube with standard solution, rinse the
vial with a small amount of the standard solution,
three times, then fill to the line. This will assure
that no dust, debris or dirt will contaminate the
standard solution that you pour into the vial. Put
a dry tube positioning ring on the tube. The tube
positioning ring has two tapered notches and one
squared-off notch. Place the ring on the tube so
that the one squared-off notch is aligned with the
vertical, white indexing line that extends 90° from
the horizontal fill line on the tube. This will assure
that you properly index the tube inside the light
chamber each time. Wipe any liquid that may
have leaked between the positioning ring and tube
surface. Cap the tube and apply an Avery label
marked with the corresponding NTU value.

Unstable Readings

Unstable readings can occur when excessive
physical change occurs in the sample at the time
that the sample is scanned in the meter. Settling
and sedimentation can cause this in high turbidity
waters and even microscopic air bubbles and
submicron particulates can cause this in low
turbidity waters. The ERR4 “Processing Error”
may be triggered in response to these situations.

To obtain the most accurate and stable readings
possible, utilize the signal averaging feature
of the meter. Turn the meter on and select
Options, then Averaging. Choose between 2, 5
or 10 measurements. Press OK, then press the
back button to return to the main menu. Signal
averaging of 5 measurements is usually sufficient
and provides optimal balance of the signal
averaging benefits, with minimal stress to the
battery.

Power Problems

Be sure to use brand name 9V alkaline batteries.
Heavy Duty, Rayovac and store brand batteries
do not have enough sustained power to keep
the meter on and power the lamp. We suggest
Duracell Alkaline 9V batteries. Rechargeable
batteries can be used; we suggest Duracell or
Energizer 9V NiMH rechargeable batteries. If
using the meter in a lab setting, remove the
battery altogether and operate exclusively with the

appropriate type of AC Adapter designed for the
2020e and 2020i meters. LaMotte offers the AC
adapter as an optional accessory, code number

1754.

If there is any visible damage to the battery
connector, contact LaMotte Technical Services
for a Return Authorization Number and to make
arrangements to have your meter repaired. Any
un-authorized alterations to the meter will void the
warranty.

Calibration

See pages 32 and 33 for calibration instructions.
The 2020e and 2020i are capable of one point
calibrations. For greatest accuracy, blank the
meter first, using an appropriate 0.00NTU blank
standard. The blank reading does not count as
a calibration point. It is a reference standard for
improved low level detection and calibration. After
blanking the meter, select one standard solution
to calibrate the meter to. This can be a 1.0, 10,
100 or other formazin solution. Remember, the
meter is only capable of a one point calibration.
Calibrate to 1.0NTU if samples are expected to be

1.0NTU or less. Calibrate to 10.0NTU if samples
are expected to be greater than 1.0NTU.

If the standards are within their shelf life, try
resetting the meter to factory calibration. See
“Negative Results” above, or page 22 of the 2020
instruction manual for instructions on how to reset
your meter to factory calibration.

Err 3 Message

An attempt was made to calibrate the meter with
a zero sample. Only use the blank 0.00NTU
standard to set a blank reading, then calibrate to
LaMotte standard solutions.

Err 4 Message

Processing Error. See “Unstable Readings” above.

Err 5 Message

No blank reading. The meter has never been
blanked. Must blank meter using 0.00NTU blank
standard solution.

Err 6 Message

The meter must be re-blanked and the sample re­scanned.

Err 7 Message

Err 1 Message

Low Battery. See “Power Problems” above.

Err 2 Message

An attempt was made to calibrate the meter
outside of the allowable range. The 2020 meters
will not allow the user to recalibrate when the initial
reading of the standard solution deviates greater
than 50% of the standard concentration. A reading
of 0.49NTU is too low for a 1.0NTU standard and
calibration up to 1.0NTU will not be possible. This
may occur if the standard solutions are out of
specification or if there was a problem blanking the
meter prior to calibration.

Check to make sure that the standard solution
is appropriate for use with the 2020e or 2020i.
LaMotte Company makes the standard solutions
specifically for the 2020e and different standards
that are specific for the 2020i. Turbidity standard
solutions can not be interchanged. Confirm by
matching the code numbers on the bottles to the
2020 manual. Formazin standards may be used, if
prepared accurately and used while fresh.

Call LaMotte Technical Service at 1-800-344-3100.

Low Battery