Analysing and troubleshooting common instrument faults
In practice, due to the aging of equipment components, improper operation methods and unstable power supply voltage can cause pHS-3B-S PH meter failure, to correctly obtain the acid rain observation data to bring difficulties, the need for observers on the emergence of faults in a timely and accurate diagnosis and analysis and troubleshooting to ensure that the normal conduct of acid rain observation operations.
(1) The power has been turned on but no display of its possible causes and methods of treatment:
a. The fuse is broken and should be replaced;
b. Bad power supply or transformer, should be sent for repair or replacement;
c. Instrument circuit failure, should be sent for repair.
(2) "Positioning" adjustment is not pH 7.00 its possible causes and treatments:
a. Composite electrode replenishment solution dried up, supplement 3M potassium chloride solution or replace the electrode;
b. Composite electrode failure, should be replaced;
c. Internal potentiometer bad, should be sent for repair or replacement.
(3) "slope" adjustment is not pH 4.00 or pH 9.18 its possible causes and methods of treatment:
a. Composite electrode aging, performance decline, should be replaced;
b. Internal potentiometer is bad, should be sent for repair and replacement.
(4) pH value measurement, the reading is not stable, its possible causes and methods of treatment:
a. The water sample K value is too low (such as below 10μS/cm), appropriate extension of the equilibrium time;
b. Composite electrode internal resistance is too high, life has come, should be replaced;
c. Composite electrode plug (seat) moisture or contamination, should be shut down with 95% alcohol wipe composite electrode plug (seat), dry before use;
d. unstable power supply voltage, or poor contact with the grounding wire, should be shut down to weld the grounding wire, to be stable voltage and then switch on the measurement.
(5) "Automatic" compensation, digital overflow or unstable display value, the possible causes and methods of treatment:
a. Temperature probe is not connected or bad, should be connected or replaced;
b. Temperature compensation selector switch is bad, should be sent for repair or replacement;
c. Temperature probe jack internal broken wire, should be sent for repair;
d. Instrument circuit failure, should be sent for repair.
