The electronic scale is generally composed of strain gauge type weighing sensor, signal processing circuit, display, keypad, power supply and other parts.The weight sensor converts the weight of the object into millivolt value, and the signal processing circuit amplifies, and the ANALOG to digital conversion is processed by the single chip microcomputer and then sent to the display for real-time display. The key board is composed of touching the keys, giving instructions such as switch machine, zero clearing, accumulation, counting and printing to the single chip microcomputer. The power supply part provides the whole machine energy.
Precautions for the use of electronic scales
(1) The electronic balance shall be verified or calibrated according to the national metrological verification regulations, and shall be used within the validity period specified in the certificate of qualification.
(2) The electronic balance should be placed in a stable and fixed position to avoid violent push and collision.
(3) When weighing items, the electronic scale should be handled with care and do not overload the use, so as not to damage the sensor.
(4) Electronic scales should be used in dry and ventilated (except waterproof scales) and non-corrosive atmosphere environment, and keep the scales clean.
(5) The electronic balance should be away from magnetic objects or strong electromagnetic fields, in order to avoid the electromagnetic characteristics of the electronic balance is affected and reduce the accuracy.
Two, the electronic balance daily fault maintenance method
In the daily measurement work, the electronic scale fault is often caused by incorrect use and improper maintenance.Combined with the author's many years of experience in the metrological verification and maintenance of electronic scales, this paper introduces several common troubleshooting methods of electronic scales.
1 Boot failure
For the boot failure phenomenon, the common reason is that the boot button is broken, followed by the built-in battery problem.For the button problem, the button board can be taken down to the alcohol solution soaked and dried after the test machine, the best solution is to replace.Emergency, you can change the line, with other buttons (such as print, unit, etc.) replace and in the panel can be indicated.The built-in battery is rechargeable, the voltage is generally 6 V, if the electronic scale is not used for a long time, pay attention to timely charging, so as not to damage the battery over discharge.The reasons for not starting the machine are as follows: the power fuse, power transformer and power chip are damaged, the capacity of the power filter capacitor is insufficient, and the single chip installed in the socket of the double-row straight integrated circuit is in bad contact, etc. The damaged components shall be carefully checked and confirmed with the help of the multimeter and other instruments.
Incomplete display of 2
Electronic scale display has digital tube, fluorescent display screen, LCD screen, etc., common fluorescent display display lack of stroke is the reason for the use of random throwing items caused by fluorescent screen stress pin fracture.During maintenance, it can be welded with fine enameled wire and fixed with glue. At the same time, it can strengthen the support on the back of display screen to relieve stress.Other such as digital tube, LCD display fault is generally bad pin contact, welding pin can be added.
3. Value drift
There are many reasons for the drift of the electronic balance value, first of all, to ensure the use of the electronic balance environment in the scope of the requirements of the manual, some need a certain time to start up the preheating, some built-in rechargeable battery of the electronic balance to ensure that the battery is sufficient, otherwise there will be a large error or drift of the value of the phenomenon.In addition to the above reasons, the indication drift is mostly related to the bad contact of the components on the internal sensor and circuit board.It is necessary to check whether the fixing screws and tray supports of the sensor are loose, whether the circuit board is clean, and whether the components have bad contact, etc. If necessary, the sensor and circuit can be replaced to determine the fault range.
4. Large value error
After using electronic scale for a period of time, due to the change of the use environment, the aging of internal components and other reasons, may lead to a large error in weighing.However, in practical work, improper maintenance methods of users will also lead to inaccurate weighing, which is specifically reflected in the fact that in order to keep the scale clean, users use wrapping paper or tape to wrap the scale, resulting in incomplete contact between the bottom of the scale and the package of the scale body, which directly affects the weighing result.In another case, the user randomly moves the position of the scale, resulting in a change in the use environment without adjustment to the horizontal state.In addition, the user overloads an item and causes the internal sensor to exceed its linear range, which can also cause misalignment.
After excluding the external factors that lead to the error of the indication value, the electronic balance should be calibrated again.The calibration methods of electronic scales from different manufacturers are also different, some can directly use the panel button to enter the calibration program, some need to toggle the calibration switch, some need to open the outer cover on the circuit board for jumper in order to carry out the calibration program.Therefore, we should pay attention to collect the calibration methods of each manufacturer in the daily work for backup.During calibration, note the use of the multi-point calibration method to ensure linearization of the indication values within the full range.After the calibration of the electronic balance, if there is still a large error (beyond the regulation of verification regulations), it must check whether the internal sensor is normal, it is best to use a good sensor with the same specification and model for replacement.In general, the problem is resolved satisfactorily after the sensor is replaced and recalibrated.
As long as the correct use and maintenance methods are followed, the failure rate of electronic scale is not high.In daily work, in addition to the use and maintenance methods introduced in this paper, it is also necessary to use and maintain the electronic scale according to the manufacturer's instructions.