Fault phenomenon: After turning on the power of the HP 6L laser printer, the three indicator lights "Error", "DATA", and "READY" on the operation panel light up one after another, leaving the yellow "Error" indicator light on, and the printer does not respond.
Cause analysis: For the HP 6L laser printer, the Error indicator light on the operation panel after startup indicates that the printer is out of paper, the cover is not properly covered, the photosensitive drum component is not installed or not installed properly, and there is paper jam in the printer. Follow the steps below to check and troubleshoot:
Maintenance process and troubleshooting method: First, unplug the power plug of the printer and check if the printing paper in the paper feed box at the back of the printer is installed properly. The so-called "in place" means to ensure that the front end of the printing paper presses the paper feed sensor located at the bottom of the paper feed box, and after inspection, the installation of the printing paper is correct; Then open the printer cover and check if the cover sensor is pressed into place when the printer cover is closed, as well as if the photosensitive drum component in the printer is installed properly. After inspection, no problems were found in these parts; Next, open the cover of the printer and remove the cover behind the printer to check for paper jams in the printer. Use tweezers to gently move the paper output detection sensor at the printer's paper output position and observe if the sensor is damaged, detached, or stuck. The results are also normal; Finally, remove the cover plate behind the printer and check for any damage or non return of the two feed sensors in the feed area. After inspection, it was found that a sensor (located under the paper roller assembly) could not be reset. After removing the sensor for inspection, it was found that the plastic lever type sensing arm was deformed and stuck. After replacing the sensor, the fault was resolved.
Troubleshooting experience: There are two sensors in the paper feed area of the HP 6L laser printer that detect paper: the first is located at the bottom of the paper feed box, which is used to detect the presence of printing paper in the printer; The second one is the paper transfer sensor, which is used to detect whether the paper transfer system of the printer is working properly. These two sensors both use a photosensitive shutter as a paper detection sensor, composed of a plastic lever type sensing arm and a photosensitive shutter combination. When there is paper in the feed box behind the printer and the printing paper is fed to the position of the paper transfer sensor by the paper kneading wheel, the printing paper presses against the upper part of the sensing arm at that position. Under the action of the lever force, the lower part of the sensing arm moves away from the photosensitive shutter. The photosensitive shutter is in a through state. After the main control circuit detects the signal of the printing paper in place, it starts counting until the sensor in the paper output area of the printer detects the presence of paper, If the printing paper does not reach the output sensor position within the specified time, the main control circuit determines that the printer is stuck based on the absence of information stored in the memory, and immediately interrupts the main motor to run the program. The stuck indicator light on the operation panel will light up. In this example, due to the photosensitive circuit breaker of the paper transfer sensor being constantly in the through state, the main control circuit counts from the beginning of operation. Therefore, the counting time does not match the data stored in the machine memory, and it is determined that the printer is stuck.