HP 7925D Service Manual page 3

PREFACE
I
This manual provides field service information for the Hewlett-Packard 7925D Disc Drive and is
intended for use by service-trained personnel. The HP 7925D Disc Drive is a state-of-the-art, mass-
memory (120 Mbyte) product and, because of its product design, a modular replacement philosophy has
been implemented to minimize on-site repair time. On-site troubleshooting and repair is assured
through the use of the information provided in this manual and the maintenance aids contained in the
service kit. For disc drive operating instructions, refer to the HP 7925D Disc Drive User's Manual, part
no. 07925-90911. For installation instructions, refer to the HP 7925D Disc Drive Installation Manual,
part no. 07925-90912.
WARNING
The HP 7925 Disc Drive contains magnetic material (spindle assembly and
actuator assembly), a potential hazard to personnel during shipping. Special
packaging and markings are required by the United States Government for
shipping. If reshipment of the disc drive becomes necessary, refer to the HP
7925D Disc Drive Installation Manual, part no. 07925-90912 for repackag-
ing instructions. If reshipment of the spindle assembly and/or the actuator
assembly becomes necessary, refer to section V of this manual for repackag-
ing information.
The contents of this manual are organized as follows:
• Section I provides the theory of operation in which each major circuit group is described in detail.
• Section II provides preventive maintenance information, maintenance precautions, lists standard
and special tools and test equipment required to service the disc drive, the preventive maintenance
schedule, and required preventive maintenance inspection and cleaning procedures.
• Section III provides step-by-step alignment and adjustment procedures for the disc drive.
• Section IV provides troubleshooting information which includes functional diagrams of the disc drive
and troubleshooting flowcharts.
• Section V provides step-by-step removal and replacement procedures for each field-replaceable
electrical and electro-mechanical assembly used in the disc drive.
• Section VI provides listings of all field-replaceable parts and an illustrated parts breakdown for the
disc drive, as well as replacement part ordering information.
• Appendix A provides changes and additions to the information contained in the main manual needed
for HP 7925H Disc Drive service.
Change 2 iii/iv