Turn the power on. The instrument should be in the standby mode.
Clamp the alligator clips together.
This step varies for different models:
Model 120: Change from STANDBY to mV mode
Model 210: The function switch is set to REF
Model 230: The function knob is set to mV ZERO and the operated leveer is
set to USE
Model 230A: The function selector is changed from BLANK to the desired mV
scale and the operated switch is set on pH REF/mV ZERO
Model 600: Change from STANDBY to mV
For all models, use the standardize knob to adjust the mV scale to zero.
To take readings, clamp the alligator clips to the appropriate electrodes
and place the electrodes in the solution. Be careful not to let the electrodes
touch