"Sucking" means a suction device. Its function is to suck out the semi-dried ink and gas in the ink supply system when the printer is turned on, replaced with the ink cartridge or replaced with the print head, so that the print head is filled with fresh ink to ensure normal printing. There are two common faults in suction devices: one is that the ink suction tube is damaged or falls off; the other is that the ink suction port is blocked. Both will prevent the negative pressure generated by the ink pump from acting on the printhead, making the printhead uncleanable. During actual maintenance, it was found that failures of blockage of the ink suction port are more common. Most of the failures are caused by blockage of the cavernos at the lower end of the ink suction port. After the failure is found, replace the cavernos.
8. Ink tank maintenance
Common faults in ink tanks are manifested as lack of ink or light handwriting. The reason is that the ink tank has a high working temperature, the ink is dry, or the operator pours different models of ink into the ink tank, and different models of ink react interactively. For ink tank failure, the ink tank must be cleaned and replaced with new ink.
In addition, the printhead must be cleaned every time a new ink tank is installed. The new ink tank should not be placed in places with direct sunlight and dust. The storage temperature should be 10℃-35℃ to avoid ink freezing and changes. Since the smaller the nozzle of the inkjet printer, the higher the resolution. At the same time, the smaller the nozzle, the higher the requirements for ink quality, you should try to use the ink provided by the manufacturer and avoid choosing inferior ink.
9. Toner cartridge maintenance
Toner cartridges are the most important component in laser printers, which directly affect the quality of printing. Common faults in toner cartridges are scratches, fatigue, and aging. The fault phenomena shown are dim images, black lines, etc. For fatigue failure, the toner cartridge can be left for a period of time and the failure will automatically disappear. In addition, when white lines parallel to the long edge of the paper appear in printing, most of them are caused by lack of toner inside the toner cartridge or damage to the toner cartridge. Open the upper cover of the laser printer, take out the toner cartridge and shake it left and right, and then put the toner cartridge in the machine. If the printing is normal, it means that the toner in the toner cartridge is lacking.
If there are still the above faults when printing, it is mostly due to fatigue or damage to the toner cartridge. When encountering this situation, you can use the following method to repair it: go to the chemical reagent store to buy some chromium trioxide, take 3-5 grams each time, dip it directly into the direction of the photosensitive drum axis, and wipe it gently, evenly and without omissions. Be especially careful when wiping to avoid scratching the photosensitive tympanic membrane with nails and other hard objects. You should not use too much force to prevent the photosensitive tympanic membrane from being worn out and the photosensitive drum is scrapped. In this way, the fatigued photosensitive drum surface layer can be removed to expose the photosensitive surface that has not yet been aged. After the above-mentioned repaired photosensitive drum, more than one or two thousand sheets of paper can be re-output, so that the life of the photosensitive drum can be continued. If the photosensitive film of the photosensitive drum has fallen off, this method can not be used to repair it, and only a new drum will be replaced.
10. Analysis and inspection methods for high-voltage circuit failures
In the laser printer, there is a set of high-voltage power supplies of about 6000V, providing high voltage for the initial charging and transfer discharge of the photosensitive drum assembly. The failures in high-voltage circuits are mainly reflected in the following two aspects:
1. The circuit itself fails when the high voltage occurs. The fault of the high-voltage circuit itself is caused by the damage to the oscillation circuit module (or integrated circuit) and the high-voltage winding open circuit of the high-voltage pulse transformer (the wire diameter of the high-voltage winding is thinner and easy to be disconnected). When encountering such a fault, you must turn on the machine and use a multimeter to directly measure the DC resistance value of the high-voltage winding of the high-voltage pulse transformer to determine whether it is open.
2. Poor contact contact. Poor contact contact refers to: due to long-term use, the toner in the printer causes poor contacts of the high-voltage output contacts of the high-voltage generator to contact with the developing bias contact points on the photosensitive drum assembly; the ground contacts of the photosensitive drum on the circuit board of the high-voltage generator are poorly contacted with the ground contact points on the photosensitive drum, resulting in the phenomenon that the printed page is completely white or completely black. The method of checking this fault is to turn on the machine, take out the photosensitive drum assembly, and check whether there is dirt or toner on several related contacts in the printer, and whether there is dirt or toner on the contacts on the photosensitive drum assembly.
11. Laser beam generator (laser head) is faulty.
Laser beam generator (laser head) fault refers to laser diode failure, mainly caused by damage to the laser diode, aging of the coating on the focus lens (in order to broaden the modulation frequency band of the laser beam, the laser beam must be focused), etc., which leads to the printer's failure of the printing page being completely white or the resolution of the printer is reduced. The method of checking this fault is to open the machine, take out the laser, then open the cover of the laser, and use a multimeter to directly measure the DC resistance value of the laser diode (there are three pins). Check whether the coating on the surface of the focus lens is aging, dust or spots.
12. Fixing heater fault maintenance method
The secondary electrostatic latent image generated by the laser beam is transmitted to the photosensitive drum. The magnetic roller in the photosensitive drum component is converted into a visible negative charge toner image on the photosensitive drum. Then, under the action of a high-voltage positive charge, the visible toner image is transferred to the printing paper. Finally, the fixing heater is pressurized and the printing paper is heated at the same time, so that the toner on the printing paper is melted, immersed in the paper, and a permanent image is formed on the paper. Fixing heaters in laser printers generally include lamp tube heaters and ceramic sheet heaters. The main manifestations of the fixing heater failure are in the following three aspects:
1. The heater is damaged. Damage to the heater refers to the damage of the heating lamp tube or the heating ceramic sheet. When this phenomenon occurs, the image on the printed page will not be fixed firmly, and the toner will fall off as soon as you touch it with your hand. In severe cases, the printer does not print, and the fault information appears (the panel indicator light will be fully lit in laser printers such as HP 4L, HP 5P/6P, HP 6L, HP100, Lenovo LJ6P, and other information will appear in laser printers such as FUSERERROR). The inspection method is to turn on the machine, take out the heater, and use the multimeter to directly measure the DC resistance value of the heating lamp or heating ceramic sheet, and replace it if there is any damage such as circuit breaker or other damage.
2. The heater temperature sensor is damaged. In order to keep the fixing heater constant temperature during the printer's printing waiting stage (STAND BY), initial rotation stage, and print rotation stage, the fixing heating components of the laser printer are equipped with a fixing heating controller composed of a heater temperature detection sensor and its control circuit and a safety protection circuit (hot fuse). For the heating ceramic sheet, its temperature detection sensor is integrated on the ceramic sheet, and for the heating lamp tube, its temperature detection sensor is closely attached to the heating roller outside the heating lamp tube. When the heater temperature detection sensor is damaged, the fixing temperature will be out of control, resulting in the fixing temperature being too high or too low, and the print page being too fixed or too shallow (the printed image is easily erased). The inspection method is to turn on the machine and take out the heater. For the ceramic heating sheet, use a multimeter to directly measure the DC resistance value of the temperature detection sensor on the side of the hot ceramic sheet; and for the heating lamp, the sensor resistance value under the heating roller should be measured after taking out the heating lamp and removing the heating roller. If it does not match the standard value, it should be replaced.
3. The fixing film is damaged. In order to prevent the toner on the printing paper from being transferred secondary during the fixing and heating of the printer, a PTEE resin is covered with a PTEE resin (bulb heater) or a Teflon film that can rotate freely on the heater is directly installed outside the ceramic heating sheet. Due to certain reasons, such as improper processing of paper jams, foreign objects enter the fixing roller, etc., causing local damage to the fixing film, resulting in a certain area of the printed image being unable to fix it firmly or the printed image being printed has regular powder depilatory. The inspection method is to turn on the machine, take out the heater, and check whether the fixing film is damaged.
13. Maintenance of paper pickup roller faults
The paper picking roller of the laser printer is one of the consumable parts. When printing, when the paper in the paper holder is normal and the paper cannot be retrieved, it is often caused by the paper pickup roller being worn or the spring being loose, the pressure is insufficient, and the paper cannot be sent to the machine. During inspection, rubber bands can be wrapped around the paper pickup roller. If troubleshooting is done, it means that the paper pickup roller is worn. Otherwise, it means that the paper picking roller is normal, and the fault may be caused by improper installation of the paper tray and poor paper quality (too thin, too thick, and moisture).
14. Maintenance of developing roller faults
When the laser printer outputs blank paper, the developing roller generally does not absorb toner. At this time, it can be measured whether the DC bias voltage of the developing roller is normal; if it is not normal, the DC bias circuit should be repaired. If the DC voltage is normal and the printer outputs blank paper, it means that the shadow roller is obviously damaged or the photosensitive drum is not grounded. When the negative charge of the photosensitive drum cannot be discharged to the ground, the laser beam cannot function on the photosensitive drum and the printing paper cannot print out the text. Check whether the developing roller is damaged and whether the developing part is installed in place.
15. Toner cartridge fault maintenance
When irregular toner traces appear on the print, it is mostly caused by the powder leak in the powder box. The powder box can be removed for inspection. The powder leakage failure of the powder box is divided into two categories: toner box leakage and waste powder box leakage. Intuitive detection of dismantling the machine can find the specific part of the fault.
16. Quick maintenance method for optical devices
Common faults of optical devices are mainly displaced or dirty optical lenses. When the optical lens is shifted, there will be no printing failure. Even if it can print, there will be incomplete printing; when the optical device is dirty, regular spots often appear in the print. Conversely, when the above phenomenon occurs in the printer, it means that the optical device is faulty. Clean and repair optics.
17. Quick maintenance method of corona wire
The corona wire of the laser printer is equipped with a high voltage voltage. The failure of the corona wire is mainly manifested in the absence of characters and the appearance of blank paper.
When such faults occur, it is important to check whether the corona wire is open and whether the high voltage of the corona wire is low or 0V. For open circuit failure of corona wire, the disassembly can be visually checked. For abnormal high voltage failures, it is possible to determine whether the high voltage on the corona wire terminal is normal.
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