The inaccurate reading of the online pH controller may be caused by various factors. The following are common problems and quick troubleshooting methods:

Electrode contamination or aging: If the electrode surface is covered with oil, protein, or chemical deposits, it can cause slow response. Dilute hydrochloric acid or specialized cleaning solution can be used for soaking and cleaning. If the response time of the electrode in the buffer solution exceeds 1 minute, it needs to be activated or replaced with a new electrode.

Calibration failure: The calibration solution is prone to absorb CO ₂ and deteriorate after opening, requiring the use of newly prepared or opened buffer solutions. When calibrating, the principle of "two-point calibration" should be followed. First, use pH6.86 buffer solution for positioning, and then adjust the slope with pH4.01 or 9.18 buffer solution to ensure that the slope is between 95% and 105%.

Wiring problem: Loose connection between electrodes and instruments or internal cable breakage can cause signal interruption. After shutting down, unplug the electrode and use an ohmmeter to check if the circuit is conductive. If the cable breaks, it needs to be replaced.

Reference electrode failure: Crystallization of reference solution, insufficient electrolyte, or blockage of liquid interface can affect potential stability. Check the reference liquid interface to ensure sufficient electrolyte and normal flow rate, and replace the reference electrode if necessary.

Temperature interference: Low temperature will increase the internal resistance of the electrode, resulting in slower response. If the sample temperature is below 10 ℃, the electrode should be preheated to room temperature before measurement, and the temperature compensation function should be confirmed to be enabled.

Sample characteristics mismatch: Samples containing silver ions and sulfides may react with KCl from the reference electrode to form precipitates, blocking the liquid interface. An anti pollution reference system (such as ceramic core or PTFE annular gap electrode) should be selected.

Electromagnetic interference: Electromagnetic fields generated by large motors, transformers, and other equipment may interfere with measurement signals. The controller needs to be kept away from the interference source or connected to the sensor using shielded cables.

Unstable power supply: Power supply fluctuations can cause instrument readings to jump. Check if the power cord is in good contact and install a voltage regulator if necessary.

Software setting error: The instrument mode has not been switched to pH measurement mode, or the temperature unit is set incorrectly, which can cause abnormal display. Need to check the screen display mode and confirm that the temperature unit is Celsius.

Improper storage of electrodes: Dry electrodes or broken glass film can lead to decreased performance. The electrode should always be immersed in a dedicated KCl protective solution to avoid mechanical impact or contact with organic solvents.

Suggested troubleshooting process:

Clean the electrode and recalibrate it;

Check the wiring and power supply;

Confirm the compatibility between sample characteristics and electrodes;

Eliminate environmental interference factors.

If the problem is still unresolved, it is recommended to contact the supplier for professional maintenance.