HP LaserJet 4 Service Manual - Page 270

Table 7-15 Right-Hand Image Missing 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 7-16 Small Print Voids Possible Cause Action Small voids on black, or near-black Replace the EP Toner Cartridge. If the printed images may be caused by printer is installed in a hot or humid imbedded toner on the location, tell the customer to move the electro-photographic drum. Cartridges printer to a better location. that are run for long periods of time in high temperature and humidity conditions may develop this problem. Table 7-17 Random Horizontal Black Lines Possible Cause Action Laser/Scanning Assembly misaligned or Replace the Laser/Scanner Assembly. damaged. DC Controller PCA Replace the DC Controller PCA. Table 7-18 Vertical White Streaks 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 Replace the Laser/Scanning Assembly. Assembly may be contaminated, blocking (or diffusing) the laser light. 7-40 Troubleshooting