HP 4550 Service Manual - Page 243

General paper-path checklist
Verify that media is correctly loaded in the input trays and that all length and width guides are set correctly.
Clean the printer. Toner and paper dust in the paper path inhibit free movement of media through the printer and block the sensors.
Vary the input and output selections of the printer to determine if the problem is associated with a particular area of the printer.
Worn separation pads on the multipurpose tray can cause multifeeds. Check the condition of the pickup rollers and customer replaceable feed roller. Bent separation tabs can cause misfeeds and multifeeds. Replace the tray if necessary.
Defective paper tray switches can cause jams by communicating the wrong size paper to the formatter.
Scraps of media left in the paper path can cause intermittent jams. Always check that the paper path is clear when cleaning the printer and when clearing jams. Also, remove the fuser and carefully check it for jam debris.
There are five areas in which jammed scraps can be difficult to find: • The ITB drawer connector on the engine side. • The OHT sensor under the registration plate. • The fuser; remove the fuser to check it carefully. • The center of the web transport before the fuser. • Inside the ITB; Rotate the belt by rotating the two white knobs on either side of the ITB to clear jam debris. Print media checklist Many print problems are caused by printing on media that does not meet specifications. The HP LaserJet Printer Family Print Media Guide contains detailed information about media specifications (see page 325 for ordering information). Refer to the following list for common mediarelated printing problems.
Rough paper causes poor toner transfer and smeared print problems. Check that the paper meets specifications for smoothness.
The printer handles only 60 to 176 g/m2 (16 to 47 lb) bond media when the media is less than or equal to 148 mm (5.8 inches) wide. If the media is more than or equal to 148 mm (5.8 inches) wide, the printer can handle only 60 to 135 g/m2 (16 to 36 lb) bond. Use transparencies that are 0.13 mm (5-mil) thick.
Paper that has absorbed moisture causes paper feed problems. When the printer is used in a humid area, damp paper might be the cause of recurring paper feed and print quality problems.
Damaged paper, paper with ragged edges, or paper whose edges stick together cause jams.
Using paper that has already been through a laser printer or a copier can cause jams.
Print quality can degrade if media with a high resistivity is being used, specifically when duplexing. C7085-90921 Chapter 7 Troubleshooting 241