Common faults of pH meter
1. There is no response when booting
Causes of failure: 1) The circuit is not connected; 2) The external voltage is unstable; 3) The instrument is damaged.
Troubleshooting method: 1) Check whether the power supply has a voltage output; 2) If the instrument connected to an external regulated power supply does not respond when turned on, check the output of the regulated power supply, and there should be a DC voltage of 9V; 3) Replace or repair according to regulations.
2. There is no display when booting
Causes of failure: 1) The wiring potentials of the LCD screen and the main board do not match; 2) The connection between the main board and the LCD screen is in poor contact or the instrument is damaged.
Troubleshooting method: 1) If the backlight is on but there is no display number, adjust the potentiometer on the main board; 2) Replace or repair according to regulations.
3. An error is displayed when starting up, and the words Err appear
Cause of failure: Desktop or portable pH meters generally have a self-test function. When the instrument detects that there is a problem with the memory chip, this message will be displayed.
Troubleshooting method: shut down, wait a moment, restart the pH meter several times, if the problem persists and the chip cannot be recovered, please contact a professional engineer for maintenance.
4. The mV area of the instrument is wrong or the measurement is incorrect
Causes of failure: 1) When the input potential exceeds the measurement range, the instrument will display the word "Err" in the mV area; 2) The electrode performance is not good; 3) The measurement channel is set incorrectly; 4) The electrode plug is in poor contact.
Troubleshooting method: 1) Reduce the input value; 2) Replace the good electrode; 3) Reset the measurement channel; 4) Connect the short-circuit plug, the instrument should display about 0.0mV, otherwise there is a problem with the pH measurement unit.
5. Incorrect pH measurement
Causes of failure: 1) The electrode performance is not good; 2) The measurement channel is set incorrectly; 3) The electrode is not calibrated or calibrated incorrectly.
Remedy: 1) Replace the electrode with good performance; 2) Reset the measurement channel; 3) Re-calibrate the electrode or replace the standard solution.
6. The pH meter is unstable during measurement
Causes of failure: 1) Whether the electrode interface is loose; 2) The instability in the measurement of pure water or desalted water is due to the lack of impurities in the water and poor conductivity.
Troubleshooting method: 1) Insert the short-circuit plug into the instrument. If the display is stable, consider replacing the electrode; 2) Calibrate with standard buffer solution.
7. For portable pH meters with touch screen, the positioning of the touch screen is inaccurate.
Cause of failure: There is drift phenomenon after long-term use.
Remedy: re-calibrate the touch screen in the instrument settings.
