HP LaserJet 4 Service Manual - Page 155

6 Removal and Replacement This chapter describes the complete disassembly of the printer from the beginning. In every instance, tasks that must be performed before beginning the procedure are listed first. Remove the assemblies in the order listed to prevent damage during re-assembly. Removal and replacement of user-replaceable maintenance items is shown in Chapter 4, "Preventive Maintenance." These items include: • All Pickup Rollers and Separation Pad • Transfer Roller Replacement • Installing the Toner Cartridge Servicing the printer involves replacing printed circuit and electro-mechanical assemblies. Do not repair component failures within these assemblies. In all instances, replace the failed assembly. The assembly procedure is the reverse of the removal procedure, except where specific instructions are provided. Caution Power-off the printer and disconnect the power cord from the power outlet and the printer before servicing the printer. Some sheet metal edges, particularly around the formatter cage, are sharp. Be careful when working in these areas to avoid being cut. Note The printer contains parts that are sensitive to Electrostatic-Static Discharge (ESD). Always observe proper ESD procedures when servicing the printer. This symbol: appears in this chapter when the parts being serviced are especially susceptible to ESD damage. Removal and Replacement 6-1