Troubleshooting and maintenance of electronic balance

Common faults and maintenance of electronic scales:

(1) the fault analysis that the weighing material can not return to zero after removal

Check the output signal of the sensor value is in standard (A/D amplification / use code code / the lowest interest rate range), if the signal is not in standard, adjust the sensor adjustable resistance, the signal value to standard, such as compensation cannot check whether there is a problem in sensor, ensure the sensor output (normal stable scale body) case, lock instrument fault, general amplifying circuit and A/D conversion circuit problems according to circuit principle analysis to determine the test one by one, the ultimate solution to the problem.

(2) inaccurate analysis of weighing;

Observation of code value is stable, the electronic meter parts sensor platform scale weight whether there is friction phenomenon, power supply is stable, operational amplifier circuit is normal, using weights weighing whether the average four scale test. Further instrument local analysis or weight correction following instructions.

(3) unable to start the fault

Make sure the problems of non fuse, power switch, power line and voltage switch, check whether the transformer has AC voltage input and AC output. If the meter comes with a battery, remove the battery and switch on with the AC power to see if the battery is low in voltage. Second, detect rectifier circuit, voltage regulator circuit and display drive circuit is abnormal, if these are no problem, check whether the processor and its auxiliary circuit is burned out.

(4) display garbled code

Remove the original display circuit and replace it with a normal display circuit to see if it is normal. If the display is normal, indicating that the display circuit has problems, if not normal, you should check the drive circuit for failure, and finally check whether the processor shows whether the output pin is in the reasonable range of output.

(5) the button is not easy to use

The first key replacement test, new key function is normal, it can be considered as key is bad, line between the measurement key and CPU, no circuit. Check if the key holder is out of contact. Measure the buttons, the diode on the CPU circuit, resistors, etc., whether there is short circuit or circuit breaker.

(6) can not be called full load

Almost impossible to return to zero, most likely due to a small signal input range has changed. In accordance with the "can not return to zero" method of detection, if you can not find a problem, first detect the power supply, A/D circuit is normal, and then detect the sensor output.

(7) sensor fault identification method

The static measurement method: use the multimeter ohm files, respectively measuring sensor E+ of S+, S- (or E- or of S+, S-) resistance is the same, general error compensation in 0.5 would need to be done, such as excessive error (2 or above) is recommended to replace the sensor.