HP 4550 Service Manual - Page 141

Introduction Removal and replacement strategy This chapter explains how to remove and replace major printer components. (HP does not support repairing individual subassemblies or troubleshooting to the component level.) Replacement is generally the reverse of removal. Occasionally, directions for difficult or critical replacement procedures are included. WARNING! The information in this section is intended for authorized service personnel only. Repair notices WARNING! Turn the printer off, wait five seconds, then unplug the power cord before servicing the printer. Failure to completely disconnect the printer could result in severe injury. Never operate or service the printer with the protective cover removed from the scanner assembly. The reflected beam, although invisible, can damage your eyes. Never operate the printer with any parts removed. The sheet-metal parts can have sharp edges. Be careful not to cut yourself when handling sheet-metal parts. CAUTION Always protect the imaging drum from light and physical contact when it is removed from the printer. HP recommends reinstalling the original cover whenever the drum is removed from the printer. Caution regarding electrostatic discharge (ESD) The printer contains parts that are sensitive to electrostatic discharge (ESD). Watch for the ESD reminder shown at the left when removing printer parts. Protect the parts that are sensitive to ESD with protective ESD pouches. C7085-90921 Chapter 6 Removal and replacement 139