7-28                                                7 Service and Maitenance 
9  Calibrate the sample probe manually. Check if indicator D2 (yellow) is 
lightened within 2 seconds when the ANALYZING UNIT POWER to ON. Press 
the switch S2 on the level detection board and then release it, then check if 
indicator D2 is first extinguished and then lightened. If it is, that means the 
calibration succeeds.   
Exercise caution to prevent the sample probe from attaching any conducting 
object during the calibration.   
 
10
Add deionized water to a clean cup. Immerse the probe tip into the water by 
2-3mm and indicator D5 on the circuit board should be lighted. Take the probe 
tip out of water, and the indicator should go out. If the test succeeds, proceed 
to the next step; if not, please contact our Customer Service Department or the 
distributor.