How to adjust the electronic balance if it encounters a fault

The electronic balance is one of the commonly used equipment in the laboratory. In order to effectively control the quality of the electronic balance in practical applications, we need to carry out regular verification. Let me share the common fault troubleshooting methods of the electronic balance, hoping to help everyone.

01 Unable to return to zero after the weighing object is removed
Check whether the output signal value of the sensor is within the standard (A/D total amplification code/use internal code range/bottom code range), if the signal value is not within the standard, adjust the sensor adjustable resistance to adjust the signal value to the standard, If it cannot be compensated, please check whether there is a problem with the sensor. Under the condition of ensuring that the sensor output is normal (the scale body is stable), lock the instrument failure. Generally, there is a problem with the amplifier circuit and the A/D conversion circuit, and then judge and test one by one according to the circuit principle. Finally solve the problem.

02 display garbled characters
Remove the original display circuit and replace it with a normal display circuit to see if it is normal. If the display is normal, it means that there is a problem with the display circuit. If it is not normal, check whether the drive circuit is faulty, and finally check whether the output pin of the processor display is within a reasonable output range.

03 Fault Analysis of Inaccurate Weighing
Observe whether the internal code value is stable, whether there is friction in each part of the sensor, whether the regulated power supply is stable, whether the operational amplifier circuit is normal, and use weights to test whether the weighing of the four legs of the weighing pan is even. According to the instruction manual, further perform partial analysis or weight calibration of the instrument.

04 Failure to boot
First make sure that it is not caused by the fuse, power switch, power line and voltage switch, and check whether the transformer has AC voltage input and AC output. If the instrument has a battery, remove the battery and turn it on with AC power to find out whether it is caused by insufficient battery voltage. Secondly, check whether the rectification circuit, voltage stabilization circuit and display drive circuit are abnormal. If there is no problem, check whether the processor and auxiliary circuits are burnt out.

05 The buttons are not easy to use
First replace the new button and test it. If the function of the new button is normal, it can be judged that the button is not in good contact. Measure whether the circuit between the button and the CPU is open or weak. Check whether the button support has poor contact. Measure the diodes and resistors on the button and the CPU circuit for short circuit or open circuit.

06 pointer beating
When the cross beam is lifted, if the distance between the edge of the fulcrum knife and the knife pad is not equal, the pointer will jump when the balance is turned on. Loosen the screw in front of the left arm of the cross bracket, and then adjust the small support by hand. the height until the pointer no longer jumps.

07 Unable to reach full load
It is similar to the situation of not being able to return to zero, most of which may be due to the change of the small signal input range. Check with the method that cannot return to zero. If you can’t find the problem, first check whether the power supply and A/D circuit are normal, and then check the sensor output.