Explanation and maintenance of common faults in electronic scales

The following phenomena occur in the electronic scale, and it should be suspected that it is a malfunction of the weighing sensor:

　　
(1) The electronic scale does not display zero, and the display screen keeps flashing.

　　
(2) After the electronic scale displays zero, the weight is added and the weighing number is not displayed.

　　
(3) The electronic scale is not accurate in weighing, and the displayed weighing numbers do not match the number of weights added.

　　
(4) The repeatability of the electronic scale is not good. Adding the same weight sometimes results in accurate weighing and sometimes inaccurate weighing.

　　
(5) When the electronic scale is unloaded or loaded, the displayed numbers are unstable, drifting or jumping.

These phenomena may all be caused by a malfunction of the weighing sensor. If it can be accurately determined that the fault is in the sensor, it can greatly improve work efficiency and accelerate the repair speed of the electronic scale. Separate the sensors that need to be judged from the system and measure the input impedance and output impedance separately. The normal input impedance value is 380 amp; Omega;, The normal output impedance value is 350 amp; Omega;, If the measurement data is not within this range, the sensor has been damaged. If there is an open circuit in the input impedance and output impedance, the sensor signal cable can be checked for any disconnection. When the signal cable is intact, it indicates that the sensor strain gauge has been burned, usually due to high current entering the sensor. When the measured input impedance and output impedance resistance values are unstable, it may be due to the insulation layer of the signal line breaking, decreased insulation performance, or the sensor being damp, resulting in poor insulation between the bridge circuit and the elastomer. The zero output signal value of the sensor is generally between (-3mv~2mv). If it far exceeds the standard range, it may be due to the sensor being overloaded during use, causing plastic deformation of the elastomer, making the sensor unusable. If there is no zero signal or the zero output signal is very small, it may be caused by the strain gauge inside the weighing sensor falling off the elastic body or having a support to support the weighing body.