Paper jam will occur in daily use of laser printers, mainly because the paper does not meet the specifications (generally, the paper used in laser printers needs 70 ~ 100g double-sided coated paper, which cannot be wet and has neat edges), and the paper conveying path is blocked by foreign objects, so it can be solved by replacing the paper and removing the foreign objects in the path. What we want to introduce here is the fault after eliminating the above problems.

test program

(1) The printed paper cannot be fed or jammed as soon as it enters the printer. The inspection procedure is as follows:

(1) Check whether the electromagnetic clutch of the pickup wheel works; if it doesn't, measure whether the coil voltage of the electromagnetic clutch is normal; if it is normal, repair and replace the clutch; if it doesn't, check the clutch drive circuit;

(3) Check whether the paper roll is stuck with paper powder, waste powder, etc. Or aging and slipping, if so, replace the paper roll;

(4) Check whether the paper tray moves. If not, repair the paper tray cam. After the above maintenance, generally speaking, the paper jam at the paper inlet can be eliminated.

(2) The printing paper is stuck in the channel, and the inspection procedure is as follows:

① Whether the printing paper is deformed in the channel, and if it is deformed, replace the printing paper;

② Check whether the channel paper sensor is normal, if not, clean the sensing window of the photoelectric sensor, otherwise replace it;

③ Check whether the paper feeding wheel slips. If it slips, the maintenance method is the same as that of the paper rubbing wheel.

(3) The printer is stuck in the fixed assembly, which is where the laser printer is often stuck. The inspection procedure is as follows:

① Check whether the lever of the channel photoelectric sensor is normally reset; If not, repair the return spring;

(2) Check whether there is molten toner accumulation on the fixing paper guide plate, and if there is, remove the accumulated waste powder;

③ Check whether the separating claw is damaged or polluted by waste powder. If yes, clean the separation claw or replace it;

④ Check whether the photoelectric sensor for paper discharge is normal. If not, clean the photoelectric sensor or return spring.

Generally speaking, the following maintenance methods can be adopted for the maintenance of the above-mentioned fault parts.

If the printer is set correctly, when there is paper in the paper box, the sensor shielding bar will be turned on by the printing paper, giving a printing command to the main processor, and the printing indicator (or the ready light on the panel) will light up at the same time. If there is paper in the paper box, the lever action of the paper sensor indicates that the photoelectric sensor is not working. Find the photoelectric sensor. After cleaning the photoelectric window of the sensor, the indicator light or the ready light should be on. If it doesn't light up, the photoelectric sensor may be damaged, so replace the sensor. The overhaul method of photoelectric induction of channel and paper outlet is the same as that of paper feed sensor.

The photoelectric sensor is normal, there is no paper feed and no paper jam. Please clean the paper roll and paper feed roller in the passage first, which can be cleaned with dry cloth and wet cloth. Some types of paper rolls can be directly removed and washed with cleaning solution, and can be used after drying. Do not use solvent to clean the paper pick-up wheel and paper feed wheel, otherwise it may make the rubber wheel sticky and damage.

If the printing paper cannot enter the printer or the supporting paper does not move, it may be that the positioning cam of the pickup clutch does not move. Open the side cover of the printer and observe whether the clutch moves when printing (be careful not to get your eyes close to the printer to prevent laser from hurting your eyes). If the clutch is running and the cam does not rotate, check whether the friction stop spring of the cam is loose, and the fault can be eliminated after repair. If the clutch does not move, measure the resistance of the clutch coil with a multimeter, which should be around 150 ohm. If the coil group is less than 100 ohm, the coil is short-circuited. The coil resistance is infinite, indicating that the coil is open, no current passes through, and can be repaired or replaced. The paper roller of HP 4VC or Canon BX printer is driven by friction electromagnetic clutch, which is difficult to repair after being damaged and can be replaced directly.

If the printer paper feeder has no dwell time, the paper feeder will drop immediately before the paper roller sends the printing paper to the printer. This shows that the friction plate of the paper supporting cam or the paper picking clutch is inert. Wash the friction plate with acetone or clean the clutch with alcohol.

After the above maintenance, if there is still a paper jam. It should be considered that there is a foreign body blocking the passage of printing paper at the paper jam position, or that there is molten toner sticking to the paper guide plate of the passage at the paper jam position, which leads to the failure of printing paper to pass smoothly. In some models that use the separation claw to separate the printing paper, the separation claw is tightly attached to the surface of the fixing heat roller by the tension of the spring. When the tip of the separation claw is stuck with melted toner and a gap is formed, after fixing, the printing paper cannot be separated from the fixing hot roller smoothly, and the printing paper is stuck. Weak spring tension of the release claw can also lead to paper jam. Don't adjust the spring too tightly during maintenance, so the separation claw will easily scratch the fluorine film on the surface of the fixing hot roller, resulting in defects in the printed image during fixing. Excessive wear or tooth loss of the transmission gear in the fixing assembly is also the main cause of paper jam failure, and attention should be paid to it during maintenance.

Several Common Faults of Laser Printer

The internal temperature of the printer is too high.

When the printer is turned on for too long and prints too much paper, the output channel temperature is too high because the printer works continuously and the heat dissipation is not good. When the temperature of the printer is too high, there will be such a situation: the paper is successfully input into the machine, but the printed sample can't be seen for a long time, and the computer shows that the printing is finished. What's going on here? When I opened the lid, I saw that the original printed proofs were crowded together and stuck in the cabin. This is because the temperature in the printer is too high. When the paper is sent out, the front end of the paper is softened by high temperature, losing its hardness and unable to move forward. However, the back of the paper is forcibly pushed forward under the strong transmission of the driving roller, forming a folding fan shape, which makes it impossible to read and proofread. When this happens, you should immediately stop printing and turn it off, open all the covers of the printer, carefully take out the folded fan-shaped paper, and let the printer fully dissipate heat. You can also gently wipe some overheated parts with cotton dipped in alcohol to cool them down as soon as possible.

There is something wrong with the printer itself.

When the host computer is used to send samples, the printer does not work. When I opened the printer, I found that there were no foreign objects in it and the temperature was not high. At this time, it is necessary to check whether the internal parts of the printer are damaged.

1. The paper pickup part is damaged.

All parts of the printer paper path are equipped with paper jam check switches or sensors. When the printer is working, it is necessary to check the passing status of the paper regularly. If a certain part does not send the paper away in time, or the paper feeding and rubbing roller does not absorb the paper, it will also report the wrong paper jam. Common causes are damaged paper pickup roller, paper pickup motor or circuit. This kind of fault can only be repaired or replaced.

2. Paper path sensor failure

Sensors are very important in the paper path. If the sensor itself is damaged, contaminated by inferior toner, dust or blocked by paper scraps, the sensor will not work normally, so the machine will always be in a paper jam state. In this case, first check whether the paper feed detection sensor and the paper discharge detection sensor are damaged. Shake the paper feed detection sensor lever to detect whether the voltage of the connector on the DC controller circuit board changes between 0-5v. If not, there is something wrong with the high-voltage power supply, and the high-voltage power supply circuit board needs to be replaced. If yes, please continue to check the DC controller circuit and the paper discharge detection sensor. In addition, you must choose high-quality professional toner.

3. Drive component failure

Slipping of driving clutch, gear and shaft will cause paper feeding disorder and paper jam. If the electromagnetic clutch is not engaged and cannot drive the paper suction roller to rotate, use a multimeter to measure whether there is voltage at its input end, and judge whether it is the clutch itself or the front power supply. If the pickup roller rotates without feeding paper, it is necessary to check whether the paper box is installed in place. If the suction roller is too dirty or has oil to reduce friction, it will not feed paper, so it should be cleaned with wet cloth or alcohol.

4. Separation component failure

The function of the separating claw is to separate the paper from the surface of the photosensitive drum. If the separation claw is damaged or the spring of the separation claw is deformed, the paper cannot be separated, resulting in paper jam, which is also one of the common causes of paper jam in printers. Damage to the separation claw may also damage the photosensitive drum, so it must be cleaned and inspected frequently.

Through the above analysis, we should pay more attention to the regular inspection of printer components and do a good job in cleaning, ventilation and paper selection. Only in this way can we avoid paper jam, prolong the service life of the printer and serve us better.

Analysis of laser printer faults from print samples

(1) There is a carrier around the developer, and the photosensitive drum absorbs the toner or the toner overflows onto the paper.

(2) The stirring device in the developer is not working properly or the toner is caked due to moisture.

(3) If the mirror or lens is polluted, please clean it.