CAUTION: There are live circuits inside the controller even when the power switch is in the
OFF position! Servicing and troubleshooting the controller must be performed by
Qualified
Service Personnel.
Section 3 (B): WEL-Transmitter Housing + Electrode Reads Low or High Versus
a Calibrated Handheld Meter; Cannot Calibrate the Electrode
pH value versus mA reading
The pH analog input menu displays the mA measured by the electrode, with a 4-20
mA range scaled to 0 to 14 pH standard units. As a reference, please see the table
below. However, these reference points may change subsequent to calibration.
If the pH (mA) reading is not correct, using a multimeter, please check the mA signal coming
from the sensor and into the controller as follows:
• Place the WEL Transmitter Housing plus Electrode in the system tee/water, or place it in
a buffer solution.
• Power down the controller. Disconnect either the red or the black sensor lead (not the
shield wire) and connect a multimeter in series as shown below to measure current (mA)
• Power up the controller. The multimeter will display the mA going to the controller from
the sensor.
o If the mA value is stuck on one value, no matter if the sensor is in the system
tee/water or in different buffer solutions, then please refer to Section 2B in this
guide.
o If the mA value differs from the from the chart above, please perform a One point
or Two Point calibration in accordance with the controller manual.
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