Aquametrix 2200C Conductivity Controller User Manual - Manual (Page 7)

3.5 Cell Connections
3.5.1 Connect the 4 wires of the cell cable to the TB2 terminal strip on the main circuit
board being sure to match the colors as printed on the TB2 terminal strip. White
and black are the electrode wires; red and green are the temperature sensor wires.
Place switches S41 and S42 in the down “on-line” position. Refer to Fig.2
3.5.2 The test resistor R68, is used for the simulation feature. It has a resistance equal to
the equivalent resistance of the cell at mid scale. The resistor that is shipped with
the unit corresponds to the mid scale of the range ordered. If the range is changed,
from the range configured at the factory. Refer to Sec. 9.1.5 for the correct resistor
value.