Shenzhen Hongxing Yongli Sorting Scanner (Handheld, Fixed, Platform, Engine) Bar Code Scanning Gun Common Fault Maintenance Methods. (Bar Code Scanning Gun Maintenance Hotline: 0755-28225517-8036)

Scanner weak laser (weak laser, weak light, weak red line, unable to read barcode, difficult to read barcode)

Reason: The laser diode is aging, and the working current can be clearly seen by the voltage source that the working current has exceeded about 50mA.

Attachment: The wavelength of the laser diode of the bar code laser scanner is generally about 650nm in the red frequency band. It consists of two parts, one part is the laser emitting part LD, and the other part is the laser receiving part PD. The two parts LD and PD have a common end point B, and the common end is generally connected with the metal shell of the tube, therefore, the laser two-plate tube actually has only three feet a, B, c. The detection and judgment of the laser diode can be carried out in the following three steps:

Distinguish between LD and PD. The resistance between the three pins of the laser diode is measured by the R× 1k block of the meter. The resistance between the two pins is always about several thousand ohms. At this time, the end connected to the black pen is the PD anode end, the pin connected to the red pen is the common end, and the remaining pin is the LD cathode end, thus distinguishing the PD part and the LD part.

2. Detect the PD part. The PD part of the laser diode is essentially a photosensitive diode. The detection method with a multimeter is as follows: measure its resistance with R× 1k. If the forward resistance is several thousand ohms and the reverse resistance is infinite, it initially indicates that the PD part is good. If the forward resistance is 0 or infinite, the PD part is bad. If the reverse resistance is not infinite, but there is a resistance of hundreds of thousands of ohms or thousands of ohms, it indicates that the PD part has reversed leakage and the quality of the tube deteriorates.

3. Detect the LD part. Use the R× 1k block of the multimeter to measure the positive resistance of the LD part, I .e. the black stylus is connected to the common terminal B, the red stylus is connected to the pin a, the positive resistance should be between 10kΩ and 30kΩ, and the reverse resistance should be infinite. If the measured forward resistance value is greater than 55kΩ and the reverse resistance value is below 100kΩ, it indicates that the LD part has been seriously aged and the use effect will become worse.).

Solution: Replace the laser diode (generally speaking, replace the laser head). During the replacement process, attention should be paid to distinguishing the yin and yang of the tube, working current, anti-static measures should be taken, focal length and fixed position should be adjusted, otherwise it is difficult to read the bar code or even impossible to read. Volatile products should not be used for the glue used for fixing. At present, some bar code scanner repairmen in the line use glue with similar 502 and volatilize white gas, the lens and mirror of the scanner are damaged to varying degrees, resulting in a decrease in scanning ability.

The barcode scanner has no laser (no laser, no light, no red light, no light comes out after pressing the scan button)

Reason: The laser diode is damaged and broken down. In this case, if you press the scan button, the swing lens can still swing, but there is no laser, or sometimes just a flash of light.

Solution: Replace the laser diode

Unable to transfer data to the PC (there is sound when scanning the barcode, but there is no data display on the computer)

Reason: incorrect interface mode (USB,KB,RS232,RS485); Data line damage (especially the USB line of some scanners, which uses a chip to convert keyboard data into USB data, the chip is easy to lose programs or damage, such as domestic scanners); Interface level IC damage (such as 232 serial port chip or KB analog switch chip);

Solution: Restore the default value and reselect the correct interface mode (Note: If the scanner is connected to the PC with a serial port line, the PC needs serial port data receiving software to receive the data, such as super terminal or other third-party serial port assistants in computer communication. If the data is to be displayed on the text or at the cursor position, a 232-to-KB data software is required, which the company can provide according to customer requirements); replace the data line; Replace the interface chip;

The barcode scanner cannot decode (there is no sound when scanning the barcode, there is a normal laser, but there is no response when scanning the barcode)

Reason: The decoding CPU cannot decode; the optical module is damaged; the digital-to-analog conversion circuit is abnormal

Solution: Restore default values (restore factory settings); Replant the decoding CPU and replace the decoding CPU; Replace the optical module; Repair the digital-to-analog conversion circuit;

After the barcode scanning gun is powered on, there is no response at all (there is no sound when the data cable is plugged in, and there is no response at all)

Cause: abnormal power supply

Solution: replace the power supply; Replace the data line; Repair the power supply circuit; CPU crystal is damaged; CPU is damaged;