How to

How to troubleshoot an industrial weighing system?

How do you troubleshoot a weight scale?

  • Troubleshooting an industrial weighing system involves identifying and resolving issues that may affect its performance. 
  • This includes problems such as inaccurate readings, non-responsive displays, load cell failures, or electrical interferences.
  • Troubleshooting typically involves checking connections, calibrating the system, ensuring proper power supply, inspecting load cells for damage, and addressing environmental factors that may affect accuracy. 
  • It may also require repairing or replacing faulty components, adjusting settings, or seeking assistance from technical support or qualified technicians. 
  • Effective troubleshooting ensures the reliable operation of the weighing system, accurate measurements, and optimal performance in industrial applications.

How do you troubleshoot a weight scale?

Problems with weighing control display unit

Possible causeSolutions
The display looks to be blank and there are no visible words or digits.The display looks to be blank and there are no visible words or digits.On the keypad of the terminal, press any key. Restart the terminal’s power supply if the display is still not visible. If nothing appears on the display after a power cycle, continue to the Power Test to make sure the source of AC or DC power is working properly.If it is determined that there is external power, make sure all harnesses connecting the power supply to the main board and the display PCB are connected and free of breakage or open wire connections. The main board needs to be replaced  with help of instrument manual because there is no electricity going to the processor on it.
Missing information on the screen or unreadable dataTo determine if there are any isolated problem regions on the display, run the internal display diagnostic test. Identify whether the issue is internal to the terminal or external.In the event that there is an issue, the display board should be replaced. 
The weight display is blank or unchanging.View the status of the terminal Check to see if the weighing system’s datasheet and drawing match the excitation voltage measurement. Continue to the following step if there is voltage.Inspect the wiring that connects the terminal to the load cell or scale. Check for broken wires, sharp angles, etc.Verify the wiring connections at the load cell and scale. Check for faulty wiring, open connections, or broken wires.Check the terminal’s wiring connection. Check for faulty wiring, open connections, or broken wires.
The display indicates weight, but there is no platform connection at the terminal.The weight display can show a random figure, positive or negative, out of range, or continuously oscillating when there is no platform or load cell attached to the terminal. Electrical noise at the amplifier input produced these random numbers. These random numbers do not indicate that weighing indicator requires service.
No response from the keypad
Verify there is no discrete input that is active and coded as “Disable Keypad” if none of the keypad’s buttons are responding. Check the manual for configuration information.Use the internal keyboard diagnostic test to identify the failed keys if keypad response is imperfect or only part of the keys are having issues. If the test is unsuccessful, replace the keyboard. 
No communication from a serial port that has been programmedA device’s communication cables should be checked. Verify that the transmit and receive lines of the terminal are connected in reverse (device RXD to terminal TXD and terminal TXD to device RXD).To find out whether the issue is internal or external to the terminal, run the internal serial diagnostic test.
No network connectivityCheck the network  ports on the network and the terminal to see whether there is a physical connection between them.To resolve any current connection errors, power cycle the control unit.To find out whether the issue is internal or external to the terminal, run the internal network diagnostic test.
No discrete inputs or outputs are functional.Check the weighing control unit’s discrete input and output configurations with instrument data sheet and loop diagram

What is the common defect of weighing scale?

Display Shows Error Codes or Messages

Possible causeSolutions
Internal malfunction or software error.For further explanations of problem codes and troubleshooting procedures, consult the user handbook.
Connection issues between the scale and the display unitCheck the cables and connections between the scale and the display unit. Make sure they are properly fastened and undamaged. Replace any faulty cables if necessary.

Inaccurate Readings shown by weighing scale

Possible causeSolutions
Scale not properly calibrated. Calibrate the scale according to the manufacturer’s instructions. Adjust the zero point and perform a full calibration if required.
Environmental factors affecting measurement accuracy.Minimize environmental factors such as vibration,excessive moisture, or temperature fluctuations that can affect measurement accuracy.
Load cell or sensor issues.Check the load cell or sensor for any damage or signs of malfunction. Replace or repair the load cell if necessary. Follow the load cell troubleshooting checklist  and down load the check list with below link
Load cell trouble shooting check list
Mechanical damage or misalignment.Inspect the scale for any mechanical damage or misalignment. Align or repair the scale components as needed.
There is contact between the platform and the load cell.Make that the load cell and the pan are installed correctly and are touching each other.
Wrong weighing unitWhen performing the calibration, use weight that is accurate.
Load cell connections wrongCheck the connecters as well as the load cell.
Wrong parametersCheck the settings for the parameters.

Unstable reading 

Possible causeSolutions
load cell and bracket coming into contact with somethingMake sure that the weighing platform’s load cell, bracket, and other structural elements are properly mechanically aligned.
goods coming into contact with somewhere.Make sure the scale is set to the appropriate location.
Power supply faultyCheck the power supply and excitation voltage
Possibly a problem with the load cell or the connections.Check the load cell as well as the connecters.

Weight variation on the platform Corner

Possible causeSolutions
Overload protection stoppers and transport locks are not removed.Verify the latches and stoppers underneath the platform.
Damage to the load cell or mechanism.Use precise weight when performing the calibration. Examine the load cell with check list

Overload or Weight Capacity Exceeded

Possible causeSolutions
Load on the scale exceeds its maximum capacity.Ensure that the weight on the scale does not exceed its maximum capacity. Remove any excess weight and retry weighing.
Misuse or improper loading technique.Train operators on proper loading techniques to distribute the weight evenly and avoid overloading the scale
Overload on the electrical system or an internal short circuitCheck the load cell using the check list, and replace it if it is defective, with a new one.
A wire or component that is broken.Check the load cell using the check list, and replace it if it is defective, with a new one.

Drifting Readings or Fluctuations

Possible causeSolutions
Electrical interference.Minimize electrical interference by keeping the scale signal cables away from other electronic devices or power sources.
Loose electrical connections.Check all electrical connections and ensure they are securely tightened. Tighten any loose connections.
External vibrations or shocks.Reduce external vibrations by placing the scale on a stable surface or using vibration isolation techniques

Non-Linear Readings

Possible causeSolutions
Load cell non-linearity.If the load cell exhibits non-linear behavior, it may require recalibration or replacement. Follow the load cell check list.
Temperature variations affecting load cell performance.Temperature variations can affect load cell performance. Consider using temperature compensation techniques or installing the load cell in an environment with controlled temperature.

Unexpected Change in the Zero Point

Possible causeSolutions
Zero Balance is not uniformExamine the Zero Balance and Check load cell output signals for consistency with datasheet and check list .Check the excitation voltage as per the data sheetMechanical overloads or shocks irreversibly distort load cells, changing zero balance.
Bridge integrity is not good Check load cell insulation and bridge input/output resistance. These values should be within manufacturer tolerance.

Sundareswaran Iyalunaidu

With over 24 years of dedicated experience, I am a seasoned professional specializing in the commissioning, maintenance, and installation of Electrical, Instrumentation and Control systems. My expertise extends across a spectrum of industries, including Power stations, Oil and Gas, Aluminium, Utilities, Steel and Continuous process industries. Tweet me @sundareshinfohe

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