HP Laserjet 4 Manual
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51 ERROR Message The 51 ERROR, and the 41.2 ERROR are caused by Beam Detect failures. If the beam detect signal is lost for more than 2 seconds the error is posted as a 51 ERROR. The 41.2 ERROR can be cleared by pressing [Continue] (or Go). The 51 ERROR may be cleared by power cycling the printer. Figure 7-6 Fuser Assembly Connector Checks Action 1. Are all connectors on the DC Controller properly seated?Inspect connectors and wiring. Reseat or replace cables if necessary. 2. Is the Laser/Scanner Assembly Defective?A defective Laser/Scanner Assembly can cause a 51 ERROR by spinning the scanning mirror at the wrong speed. Replace the Laser/Scanner Assembly. 3. Is the DC Controller Defective? Replace the DC Controller. 4. Has the printer been moved from a cold to a warm room?Allow the printer to stand 6 hours until any condensation has dissipated. Table 7-1151 ERROR Beam Detect Checks Troubleshooting 7-31
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52 ERROR Scanner Malfunction The scanner motor is a flat, brushless, DC motor. Motor operation is completely controlled by the DC Controller. The scanner motor is enabled when the printer is powered-up (during the printer’s power-on self test), or whenever the PRINT command is received by the Formatter PCA. The scanner motor makes a distinctive sound when starting. The sound can be described as a “variable pitch whirring” sound. Listen for the sound of the scanner motor when troubleshooting the 52 ERROR. Laser/Scanner Assembly Functional Checks Initiate a Self Test. As the test begins, listen for the sound of the scanner motor. If the motor cannot be heard, perform the following in the order given: 1Check the Laser/Scanner and the Power Supply cables. Replace if necessary. 2Replace the Laser/Scanner Assembly. 3Replace the DC Controller. 7-32 Troubleshooting
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57 (or 57.1) SERVICE Message (Main Motor Fa i l u r e ) The 57 SERVICE indicates that the DC Controller PCA detected a general motor failure. The Main Motor drives all moving components in the printing process. The Main Motor is a 4-phase, DC servo motor controlled by the DC Controller PCA. The formatter detects a Main Motor failure when: •The Main Motor does not come up to speed within one second of receiving drive voltage. •The Main Motor deviates from the correct speed for one second after reaching the correct speed. Main Motor Functional Checks •Inspect the gear train for debris that would block the free operation of the gears. •Check the gears in the Toner Cartridge for wear and binding. •Reseat J211 (or J214 on the HP LaserJet 4 Plus/4M Plus) on the DC Controller PCA, and the main connector on the Main Motor Assembly. Refer to Figures 7-16 and 7-17 for the DC Controller PCA connector locations. •If the problem persists, check that the +24B Voltage is present on the DC Controller. If the voltage is not present, replace the DC Controller. If the voltage is present, and the motor does not rotate, replace the Main Motor Assembly (see Figure 7-11 for location). Troubleshooting 7-33
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58 (or 57.2) SERVICE (Fan Failure) The 58 SERVICE indicates that the DC Controller detected a failure in the Exhaust Fan (FM1) in the printer or the optional duplexer. When troubleshooting this problem, perform the following steps in the order given. 1Check that the fan is mounted correctly in its shroud. 2Check that the fan blades are not blocked. 3Check that the Cooling Fan connector is firmly seated on the DC Controller (see Figure 7-16 or Figure 7-17 for location). If the above checks are satisfactory, replace the fan. NoteVerify the direction of air flow. Air should blow out of the printer. 7-34 Troubleshooting
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Image Defect Summary The quality of the printer’s output is subject to the judgment of the user. This section of the manual helps you define print quality defects, and understand what factors affect print quality. The print samples shown in the following figures illustrate some print quality defects. Keep copies of print quality defects encountered in the field with an explanation of their causes for future reference. The image defects listed below are covered in the following tables. (For major assembly, connector, and switch locations, see Figures 7-11 through 7-18 later in this chapter.) •Black Pages. •Any Faint Print Condition •Faulty Registration •Vertical White Streaks. •Right-hand Image Missing. •Small Print Voids •Random Horizontal Black Lines •Repetitive Defects. •Smeared Print/Improper Fusing. •Distorted Print. •Black Pages with Horizontal White Strips. •Image Skew. •Improperly Sized Image. •Vertical Dark Streaks. •Large Print Voids. •Background Scatter. •White or Blank Pages. Troubleshooting 7-35
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Figure 7-7 Image Defect Summary 7-36 Troubleshooting
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Figure 7-8 Image Defect Summary Troubleshooting 7-37
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Possible Cause Action The HVPS connections are dirty. Clean the HVPS terminals (see Figure 7-18 for layout). The HVPS is installed improperly. If the HVPS has been removed and replaced, it may not be seated properly.Remove the HVPS, and check the connectors for damage. Reseat the HVPS, being certain to fully seat the connectors. Bad Primary Charging Roller. Replace the Toner Cartridge. The HVPS is defective. Replace the HVPS. DC Controller PCA. The laser drive circuitry is damaged so that the laser is always on.Replace the DC Controller PCA, followed by the Formatter PCA if required. Table 7-12Black Pages Possible Cause Action Printer set to Economode. Change driver and/or Control Panel settings to ECONOMODE=OFF. Toner Cartridge. Replace the Toner Cartridge. Print density set improperly. The higher the print density setting, the more toner transferred to the drum.Set the print density to a darker level. Replace the high voltage power supply if this has no effect. The paper finish, conductivity, or moisture content may not be suitable for the electro-photographic printing process.Try a known good source of paper from a freshly opened package. Refer to the HP LaserJet Family Paper Specifications Guide for media specifications. The transfer roller may be defective. Replace or reseat the roller. Weak or no developer bias. If inadequate, or no developer bias is produced, toner is not attracted to the image written on the drum.Adjust the print density setting as shown in Chapter 3. Table 7-13Any Faint Print Condition 7-38 Troubleshooting
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Possible Cause Action Paper. The surface of the paper may be too smooth for the pickup roller to move the paper through the paper path.Change paper. Try a brand of paper known to be good. Worn Pickup Roller and Separation Pad. If the Paper Pickup Roller, or the Separation Pad are sufficiently worn, the leading edge of the paper may not reach the registration assembly in time. Replace the Pickup Roller and Separation Pad together. PS1 faulty. If the Input/Registration sensor (PS1) is broken, it can not sense the presence of paper at the registration point.Replace the Input/Registration Sensor. Drive Gears. If any gear within the gear drive train becomes excessively worn or dir ty, erratic paper movement results, causing image misregistration.Examine the gears along the paper path for wear and contamination. Clean and inspect the gears. Replace any broken or defective gears. Paper Tray. The paper tray may be preventing the paper from moving through the printer.Verify that the tray is loaded correctly. Verify that the paper tray is seated fully into the printer. If possible, exchange tray with another printer to see if the problem is associated with the tray. Note the HP LaserJet 4/4M tray is NOT interchangeable with the HP LaserJet 4 Plus/4M Plus tray. The LJ5 paper trays are not compatible with the LJ4 or LJ4+. Replace the paper tray. DC Controller replaced. If the DC Controller was replaced, adjust VR202 as shown in Chapter 6. Paper Input Assembly replaced. The HP LaserJet 4/4M Paper Input Assembly is NOT compatible with the HP LaserJet 4 Plus/4M Plus. The LJ5 Paper Input Assembly is not compatible with the LJ4 or LJ4+ Input Assemblies. Installing a non-compatible Input Assembly results in paper input registration problems. Table 7-14Faulty Registration Troubleshooting 7-39
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Possible Cause Action No toner available for print. Shake/replace the EP Toner Cartridge. Laser shutter may be blocking the beam Ensure that the mechanism that lifts the shutter is functional, for example, the shutter doesn’t stick in its travel, and is lifted evenly. Table 7-15Right-Hand Image Missing Possible Cause Action Small voids on black, or near-black printed images may be caused by imbedded toner on the electro-photographic drum. Cartridges that are run for long periods of time in high temperature and humidity conditions may develop this problem.Replace the EP Toner Cartridge. If the printer is installed in a hot or humid location, tell the customer to move the printer to a better location. Table 7-16Small Print Voids Possible Cause Action Laser/Scanning Assembly misaligned or damaged.Replace the Laser/Scanner Assembly. DC Controller PCA Replace the DC Controller PCA. Table 7-17Random Horizontal Black Lines Possible Cause Action 1.No toner is available for print, or the toner level is low.Shake the EP Toner Cartridge, replace the cartridge if the problem persists. 2.The lenses within the Laser/Scanning Assembly may be contaminated, blocking (or diffusing) the laser light.Replace the Laser/Scanning Assembly. Table 7-18Vertical White Streaks 7-40 Troubleshooting