Common faults of pH meters
1. No response when turning on the computer
Reasons for the failure: 1) The circuit is not connected; 2) The external voltage is unstable; 3) The instrument is damaged.
Troubleshooting methods: 1) Check whether the power supply has 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. There should be a DC voltage of 9V; 3) Replace or repair according to regulations.
2. No display when booting
Reasons for the failure: 1) The wiring potential between the LCD screen and the motherboard does not match; 2) The connection line connecting the motherboard to the LCD screen is in poor contact or the instrument is damaged.
Troubleshooting method: 1) If the backlight is on when turning on the computer but no numbers are displayed, adjust the potentiometer on the motherboard; 2) Replace or repair according to regulations.
3. An error message appears during startup, with the word Err appearing.
Cause of failure: Desktop or portable pH meters generally have a self-test function. When the instrument detects a problem with the memory chip, this message will be displayed.
Troubleshooting method: Shut down, wait, and restart the pH meter several times. If the problem persists and the chip cannot be restored, please contact a professional engineer for repair.
4. The mV area of the instrument is wrong or the measurement is incorrect.
Reasons for the 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 setting is wrong; 4) The electrode plug has poor contact.
Troubleshooting methods: 1) Reduce the input value; 2) Replace the 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
Reasons for the failure: 1) Poor electrode performance; 2) Wrong measurement channel setting; 3) The electrode is not calibrated or calibrated incorrectly.
Troubleshooting methods: 1) Replace the electrode with good performance; 2) Reset the measurement channel; 3) Recalibrate the electrode or replace the standard solution.
6. The pH meter is unstable during measurement.
Reasons for the failure: 1) Is the electrode interface loose? 2) The instability when measuring pure water or desalted water is due to the lack of impurities in the water and poor conductivity.
Troubleshooting method: 1) Use a short-circuit plug to plug into the instrument. If the display is stable, consider replacing the electrode; 2) Use standard buffer for calibration.
7. For portable touch screen pH meters, the touch screen is not positioned accurately.
Cause of failure: Drift occurs after long-term use.
Troubleshooting method: Recalibrate the touch screen in the instrument settings.
