HP LaserJet 4250 Service Manual - Page 182

Removal and replacement strategy This chapter describes how to remove, replace, and reassemble the major assemblies of the printer. Replacement is generally the reverse of removal. To identify the left side and right side of the printer, face tray 1 on the front of the unit. WARNING! Unplug the power cord from the power outlet (at the wall receptacle) before attempting to service the product. If you do not follow this warning, severe injury can result. Certain functional checks during troubleshooting might require that power is supplied to the product. However, all power should be turned off and the product should be unplugged when you remove any product assemblies or components. Never operate or service the printer when the protective cover is removed from the laser/scanner assembly. The reflected beams, although invisible, can damage your eyes. CAUTION The product contains components that are sensitive to electrostatic discharge (ESD). Always perform service work at an ESD-protected workstation. If an ESD-protected workstation is not available, discharge body static by grasping the printer chassis before touching an ESD-sensitive component. Ground the printer chassis before servicing the product. Required tools ■ #2 Phillips screwdriver ■ Small flat-blade screwdriver ■ Needle-nose pliers ■ ESD mat (if available; see the ESD caution above) ■ Penlight (optional) ■ Tape (optional) ■ Transfer-roller removal hook CAUTION Using a pozidriv screwdriver will damage screw heads on the product. Use a #2 Phillips screwdriver. 168 6 Removing and replacing parts