What if the printer prints all black? Different printers have different solutions!

This situation may be caused by the detachment of the PCR charging roller of the laser printer. How to determine? People shake the printer's toner cartridge to see if they can hear a sound. If there is a sound, it indicates that it has come off and the toner cartridge cannot be used again. The solution is to replace the printer with a new toner cartridge.
It may also be caused by the printer's scraper flipping over. People check to see if the surface of the printer's drum is all toner, and if so, it means the scraper is reversed. People can rotate the drum core in a reversible direction and push it once (which can solve 80% of the problem) to see if the problem can be solved. If not, it indicates that the selenium drum is scrapped, and people need to replace it with a new one.
It may also be caused by poor conductivity. People stand up on the non gear end of the printer's toner cartridge and lightly tap it on the table. If it cannot be solved, the toner cartridge also needs to be replaced.
This situation in inkjet printers is mainly caused by two reasons, namely, the ink cartridge of the printer is out of ink, the printer is not used for a long time, or the nozzle is blocked due to direct sunlight. Faced with this situation, people replace the printer with a new ink cartridge or inject ink, but if the ink cartridge is not used up, it indicates that the nozzle of the printer is blocked. People remove the ink cartridge (for printers with non integrated ink cartridge nozzles, the nozzle needs to be removed) and soak the nozzle in warm water for more than ten minutes. It is important to note that people should not immerse the circuit board in water, otherwise it will be scrapped and unusable.
What should I do when printing with a needle printer?
This situation is mainly caused by four reasons: firstly, the printing ribbon has been used for a long time, secondly, the printing head has not been cleaned for a long time, thirdly, there are broken needles in the printing head, and fourthly, the driving circuit of the printing head is broken. People first adjust the spacing between the printing head and the printing roller, and then see if printing can return to normal. If not, a new ribbon needs to be replaced.
If you change the ribbon or print all black, people need to clean the print head. People remove the two fixing screws on the print head, remove the print head, and use a needle or small hook to remove the remaining stains (these stains are accumulated ribbon fibers for a long time) in the front and back of the print head. Then, a few drops of instrument oil are dropped in the area where the needle can be seen at the back of the print head to remove some dirt. After cleaning, people can empty a few sheets of paper without installing the ribbon, and finally install the ribbon to restore normal printing.
If the printing head has a broken needle or a problem with the driver circuit, it is recommended that people find someone to replace the printing needle or driver tube.