Laser printer troubleshooting

Laser printers are print output devices incorporating laser scanning technology, electronic technology, and electrostatic imaging technology. It has the characteristics of fast print speed, good print quality, high resolution, low noise, etc. It is an important computer peripheral device. With the advent of network printers, it has become more and more widely used in office automation, printing, publishing, scientific research and other industries.

Repair failure example

Fault 1: The image of a laser printer is clearly black and white. The problem still exists after the toner cartridge is replaced and all parts are cleaned.

Maintenance method: Through the maintenance of the optical part of the laser printer, the problem is solved. The main part is to open the shell of the laser printer, disassemble the black plastic box, carefully wipe the several reflective surfaces of the multi-shuttle mirror with a clean lens paper, and then put a few optical The lens is wiped clean, the removed plastic box is restored, and attention is paid to installing the terminal card connector. After turning on the machine, the printed script is full.

Fault II: A Canon ST laser printer often fails when the heat lamp is off. Only one power light is on after the power is turned on. The machine cannot work normally.

Maintenance method: It was discovered through inspection that it was not a problem with the fuser, nor was it a problem with the power supply or the small relay. Instead, a 102 J small resistor heated by a small box next to the power box was not in good contact with the circuit board because it was a two-sided circuit. Plates, to be welded on both sides, the use of electrochromic welding after welding troubleshooting. This failure is common in ST laser printers, but sometimes the heating lamp does not light is a one-way thyristor fault in the power control section. Fusing lamps, thermistors, and thermal protectors are also common. If measuring the fuser lamp burns out, the thermistor performance is not good, the open circuit of the thermal protector should be replaced.

Fault 3: The heat lamp of a Canon BXII laser printer is sometimes bright and sometimes not bright.

Maintenance methods: When the heat lamp does not light, use a multimeter to check the two lamp's connection line is broken, there are no 7 fine wire broken, because the BXII and KT laser printer fixing part and the host connection is active , Several wires are often disassembled and disassembled easily. If the heater lamp does not light up often, but it can be used normally after cooling for a long time, this is a problem with the thermistor. Replace the new thermistor, the fault can be resolved. Use a multimeter to measure the normal thermistor cold state 320kΩ, hot 1.45kΩ.

Fault 4: The output image is light in color and cannot be seen clearly

A canon LBP laser printer, the output image light color, the basic can not see the handwriting. Try to adjust the contrast knob to the maximum, the output proofs still can not see the handwriting, consider the mirror dirt, use alcohol swab to wipe the mirror and focus lens clean, failure remains. Check if the transfer wire is normal and no abnormality is found. Clean the electrode wire and the failure has not been ruled out. Check the charging wire of the cartridge. It is in good condition and there is no problem in checking the high voltage and high voltage contacts. It means that the fault is not related to the electrode wire.

Upon further inspection, it was found that a spring plate of the sensitive sensor switch of the laser driver circuit was broken, resulting in the failure of the printer when the printer was working and causing the above failure. After replacing the new leaf spring, troubleshooting.

Fault 5: Fixer heating is abnormal

A Canon laser printer, the power indicator light is on after power-on, the ready/waiting light flashes off, the fixing heater only flashes once and no longer heats, and sometimes the power-on fixing heater does not work at all.

According to the failure phenomenon, it is suspected that the fixing heater is in poor contact or damaged. The fuser heater portion was removed, the resistance of the multimeter was detected at both ends, the thermistor and the temperature sensor and the protection circuit were detected, and no problems were found. Check the main control board control interface circuit is also no exception.

Further inspection of the heating drive circuit revealed a problem with the thyristor. After the replacement of the new thyristor, the fixing heater returned to normal operation and troubleshooting was eliminated.