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COMMON FAULTS AND TROUBLESHOOTING METHODS OF ELECTRONIC SCALES

Update:02-04-2022
Summary:

    Electronic scales are also commonly used measuremen […]

    Electronic scales are also commonly used measurement tools in life. They are often used in transactions. Frequent use will also cause damage to electronic scales. Therefore, troubleshooting and maintenance are particularly important. A large number of electronic scales are put into use, and there will inevitably be problems in maintenance and maintenance. Due to the different manufacturers of electronic scales, the problems will be various. Several common faults and the usual troubleshooting methods are as follows:

(1) After the power is turned on, the electronic scale has no response.

    First of all, check the power supply. The power supply includes an AC power supply and a regulated DC power supply. It is the "source" of the operation of the electronic scale. Therefore, troubleshooting should also start from here, in other words, it depends on whether there is a power supply. Because of different manufacturers, electronic scales have different rectification and voltage regulation voltages. Generally, 5V, 6.3V, 15V, 32V, etc. are commonly used. On the basis of ensuring that there is no problem with the power supply, further search for the source of the fault.

(2) The keyboard does not work or some keys do not work

    If the whole keyboard doesn't work, it's usually because the keyboard is damaged or the keyboard matrix has a short circuit. Replacing the keyboard or removing the matrix short point (focus on the diodes on the matrix circuit) can solve the problem.

If some keys do not work, first check whether the keys that do not work are distributed by row or column. If the problem is distributed by row, you should find the front-end circuit, generally, the front-end circuit device is damaged or has poor contact. Problems distributed by columns should be found in front-end circuits and single-chip microcomputers, which are generally caused by damage to the single-chip microcomputer or poor contact.

(3) After the power-on self-test, it shows overload or underload

    First check the sensor to check whether the input and output resistance of the sensor is normal (general input: 400 ohms, output: about 350 ohms) and whether the input and output voltage signals (in empty, whether there is any change in loading and the amount of change) are within the normal range, If the sensor is not replaced normally, secondly check whether the A/D conversion circuit is normal, mainly check whether the A/D conversion integrated amplifier is damaged and the peripheral circuit is faulty, and remove the faults that occur.

(4) After the power-on self-test, the zero point and the drift during loading

    When the electronic scale is used in a damp environment or is not used for a long time in a non-dry place, it may be damp, especially when the sensor and the A/D conversion circuit are damp, there will be short-circuited to varying degrees between the electronic circuits, and the drift will be affected. will happen. When this happens, open the electronic scale, clean up the dirt on the sensor and circuit board, and then dry it, the problem can be solved.

(5) Linearity is not good

    This kind of failure mostly occurs in the production process of electronic scales, but electronic scales in use also occur from time to time. There are two main reasons: one is that the linearity of the sensor is not good, and the other is that the resistance and capacitance of the integrating circuit of the A/D are inserted incorrectly, soldering, and the performance has deteriorated. When eliminating this kind of fault, first of all, a comprehensive inspection of the circuit should be carried out, and then some devices should be tested and replaced.

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