Removal and replacement strategy.....................................................................................................168 Required tools.....................................................................................................................168 Before performing service ..................................................................................................169 After completing service ....................................................................................................169 Screws used in the printer .................................................................................................170 Parts-removal tree .............................................................................................................171 Printer input tray, and cabinet wheel locks.........................................................................172 Dc controller PCA diagram.................................................................................................173 User-replaceable parts ......................................................................................................................175 Print cartridge .....................................................................................................................175 Transfer roller ....................................................................................................................177 Fuser...................................................................................................................................178 Tray 1 pickup roller ............................................................................................................179 Tray 1 separation pad.........................................................................................................181 Tray 2 feed rollers...............................................................................................................182 Covers, tray 1, and the rear output bin................................................................................................186 Accessory covers and the tray 2 extension door ...............................................................187 Formatter cover...................................................................................................................191 Top cover............................................................................................................................192 Right-side cover .................................................................................................................195 Left-side cover....................................................................................................................197 Front cover..........................................................................................................................198 Tray 1..................................................................................................................................200 Rear output bin...................................................................................................................203 Control-panel display...........................................................................................................................204 Control-panel overlay .........................................................................................................204 Control-panel assembly .....................................................................................................205 Main assemblies .................................................................................................................................209 Firmware DIMM (LJ 4200/4300 only).................................................................................210 Formatter assembly ...........................................................................................................211 Reinstallation notes, formatter ...........................................................................................212 Installing a new formatter and a new dc controller (LJ 4250/4350 only)............................213 Output-delivery assembly ..................................................................................................214 Duplexing-pendulum assembly...........................................................................................217 Laser/scanner assembly.....................................................................................................219 Paper-pickup drive assembly .............................................................................................222 Tray 2 lifter-drive assembly.................................................................................................227 Dc controller PCA...............................................................................................................230 Reinstallation tip..................................................................................................................235 Installing a new formatter and a new dc controller (LJ 4250/4350 only)............................235 Power supply......................................................................................................................236 Paper-feed belt assembly...................................................................................................243 Motors and fans...................................................................................................................................245 Main cooling fan (left side) .................................................................................................246 Cooling fan, right side (HP LaserJet 4250/4300/4350 Series printers only) .....................248 Removing the fan without removing the air duct................................................248 Removing the fan and the air duct together.......................................................251 Print-cartridge motor (HP LaserJet 4250/4300/4350 series printer only)...........................253 Main motor .........................................................................................................................255 Pickup and feed assemblies ...............................................................................................................257 viii