HP HP 7936 Installation instructions

HEWLETT-PACKARD
liP 7936 AND HP 7937 DISC DRIVES
HARDWARE SUPPORT MANUAL

CERTIFICATION
Products, materials, parts, and services furnished on this order
have been provided in accordance with all applicable Hewlett-
Packard specifications. Actual inspection and test data per-
taining to this order is on file and available for examination.
Hewlett-Packard's calibration measurements are traceable to
the National Bureau of Standards to the extent allowed by the
Burea u 's calibration facilities.
The Hewlett-Packard Quality Program satisfies the require-
ments of FAR 52.246-15.

HP 7936 and HP 7937 Disc Drives
Hardware Support Manual
Manual part number: 07937-90903
Microfiche part no. 07937-90803
Printed: JANUARY
1987
Printed in U.s.A.
MODELS COVERED
Edition 1
E0187
This manual covers the following models: HP 7936H, 7937H,
7936XP, 7937XP.
OPTIONS COVERED
In addition to the standard model, this manual covers the
following options:
015, 017.
r/;O- HEWLETT
a:~ PACKARD
HEWLETT-PACKARD
P.O. Box 39, Boise, Idaho 83707-0039

Notice
The information contained in this document is subject to change without notice.
HEWLETT-PACKARD MAKES NO WARRANTY
OF ANY KIND WITH REGARD TO THIS
MATERIAL, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. HEWLETT-PACKARD shall
not be liable for errors contained herein or for incidental or consequential damages in connection with the
furnishing, performance or use of this material.
HEWLETT-PACKARD assumes no responsibility
for the use or reliability of its software on equipment
that is not furnished by HEWLETT-PACKARD.
This document contains proprietary information, which
is protected by copyright. All rights are reserved.
No part of this document may be photocopied, reproduced or translated to another language without the
prior written consent
of HEWLETT-PACKARD Company.
2
Copyright @ 1987 by HEWLETT-PACKARD
FOR U.S.A. ONLY
The Federal Communications Commission (in 47 CFR 15.818) has specified that
the following notice be brought to the attention of the users of this product.
FEDERAL COMMUNICATIONS COMMISSION
RADIO FREQUENCY INTERFERENCE
STATEMENT
Warning: This equipment generates,
uses, and can radiate radio frequency energy and if not instal-
led and used in accordance with the instructions manual, may cause interference to radio com-
munications. It has been tested and found to comply with the limits for Class A computing devices
pursuant
to Subpart J of Part 15 of FCC Rules, which are designed to provide reasonable protec-
tion against such interference when operated in a commercial environment. Operation of this
equipment in a residential area
is likely to cause interference in which case the user at his own ex-
pense will be required to take whatever measures may be required to correct the interference.

Printing History
New editions are complete revisions of the manual. Update packages, which are issued between editions,
contain additional and replacement pages
to be merged into the manual by the customer. The dates on the
title page change only when a new edition
or a new update is published. No information is incorporated
into a reprinting unless it appears
as a prior update; the edition does not change when an update is
incorporated.
A software code may be printed before the date; this indicates the version level
of the software product at
the time the manual or update was issued. Many product updates and fixes do not require manual changes
and, conversely, manual corrections may
be done without accompanying product changes. Therefore, do
not expect a one-to-one correspondence between product updates and manual updates.
Edition 1
..................................................... JANUARY 1987
Herstellerbescheinigung
Hiermit wird bescheinigt, daB das Gerat/System HP 7936/7937 in Obereinstimmung mit den Bestimmungen
von Postverfiigung 1046/84 funkentstort
ist.
Der Deutschen Bundespost wurde das Inverkehrbringen dieses Gerates/Systems angezeigt und die
Berechtigung zur Oberpriifung der Serie
auf Einhaltung der Bestimmungen eingeraumt.
Manufacturer's Declaration
This is to certify that the product(s) HP 7936/7937 is in accordance with the Radio Interference
Requirements
of Directive FTZ 1046/1984. The German Bundespost was notified that this equipment was
put into circulation; the right to check the series for compliance with the requirements was granted.
Additional Information for Test and Measurement Equipment
If Test and Measurement Equipment is operated with unscreened cables and/or used for measurements on
open setups, the user has to assure that under operating conditions the Radio Interference Limits are still
met
at the border of his premises.
3

Safety Considerations
GENERAL -This product and related documenta-
tion must be reviewed
for familiarization with
safety markings and instructions before operation.
SAFETY SYMBOLS
...L..
Instruction manual symbol: the product
will be marked with this symbol when it
is necessary for the user to refer to the
instruction manual in order to protect
the product against damage.
Indicates hazardous voltages.
Indicates earth (ground) terminal.
WARNING
The WARNING sign denotes a hazard.
It calls attention to a procedure or prac-
tice that,
if not correctly performed or
adhered to, could result in personal in-
jury. Do not proceed beyond a
WARNING sign until the indicated
conditions are fully understood and met.
ICAUTION I
The CAUTION sign denotes a hazard.
It calls attention
to an operating proce-
dure
or practice that, if not correctly
performed
or adhered to, could result in
damage to or destruction of part or all
of the product. Do not proceed beyond
a CAUTION sign until the indicated
conditions are fully understood and met.
SAFETY EARTH GROUND -This is a safety
class I product and
is provided with a protective
earthing terminal. An uninterruptible safety earth
ground must be provided from the main power
4
source to the product input winng terminals,
power cord,
or supplied power cord set. Whenever
it
is likely that the protection has been impaired,
the product must be made inoperative and be
secured against any unintended operation.
BEFORE APPLYING
POWER -Verify that the
product
is configured to match the available main
power source according
to the input power con-
figuration instructions provided in this manual.
If this product is to be operated with an autotrans-
former make sure
that the common terminal is
connected to the earth terminal of the main power
source.
SERVICING
WARNING
Any servlcmg, adjustment, maintenance, or
repair of this product must
be performed only
by service-trained personnel.
Adjustments described in this manual may
be
performed with power supplied to the product
while protective covers are removed. Energy
available
at many points may, if contacted,
result
in personal injury.
Capacitors inside this product may still
be
charged after the product has been disconnec-
ted from the main power source.
To avoid a fire hazard, fuses with the proper
current rating and of the specified type (nor-
mal blow, time delay, etc.) must be used for
replacement. To install or remove a fuse, first
disconnect the power cord from the device.
Then, using a small flat-bladed screw driver,
turn the fuseholder cap counterclockwise until
the cap releases. Install either end of a prop-
erly rated fuse into the cap. Next, insert the
fuse and fuseholder cap into the fuseholder
by
pressing the cap inward and then turning it
clockwise until it locks in place.

List of Effective Pages
The List of Effective Pages shows the edition or update number of all pages. Within the manual, any page
changed since the last edition
is indicated by printing the update number on the bottom of the page.
Changes are marked with a vertical bar in the margin.
If an update is incorporated when an edition is
reprinted, these bars are removed. No information is incorporated into a reprinting unless it appears as a
prior update.
To verify that your manual contains the most current information, check that the version
printed
at the bottom of the page matches the version listed below for that page.
Effective Pages Version
all
.................................................................................. Edition 1
5

Chapter 1
Product Information
Contents
Page
1-1
Introduction .' ................................................................................................ 1-1
Product Description ......................................................................................... 1-1
Documentation Supplied .................................................................................... 1-2
Supporting Documentation .................................................................................. 1-2
Product Structure ............................................................................................ 1-2
Specifications ................................................................................................ 1-2
Serial Number ............................................................................................... 1-2
Supported Eq,uipment ....................................................................................... 1-2
Test Equipment Required .................................................................................... 1-2
Warranty ... " ................................................................................................ 1-2
Support Strategy ............................................................................................. 1-2
Chapter 2
Site Planning and Requirements Page
2-1
Introduction ................................................................................................. 2-1
Site Planning ................................................................................................. 2-1
Specifications ................................................................................................ 2-1
Cabling Limitations .......................................................................................... 2-1
Chapter 3
Installation And Configuration Page
3-1
Introduction ................................................................................................. 3-1
Shipping Latch ............................................................................................... 3-1
Drive Installation ............................................................................................ 3-2
Primary Power Requirements ............................................................................... 3-2
Controls, Indicators, and Connectors ........................................................................ 3-2
Line- Switch .............................................................................................. 3-2
Channel Address/Diagnostic Switch ...................................................................... 3-2
Run Time Mode ....................................................................................... 3-3
Diagnostic Mode ...................................................................................... 3-3
LED Display .............................................................................................. 3-4
HP-IB Connector ......................................................................................... 3-4
Power Fuse ............................................................................................... 3-4
Line Connector ........................................................................................... 3-4
CPU Connection -HP-IB Systems ........... " ............................................................... 3-4
7

Contents (continued)
HP-IB Cabling ............................................................................................ 3-4
HP-IB Device Address .................................................................................... 3-5
Chapter 4 Page
4-1
Preventive Maintenance
Introduction ................................................................................................. 4-1
Chapter 5 Page
5-1
Functional Description
Introduction
................................................................................................. 5-1
Block Diagrams .............................................................................................. 5-2
Signal
Notation .............................................................................................. 5-2
List of Mnemonics ........................................................................................... 5-2
Disc
Format ................................................................................................. 5-3
Addressing Structure
......................................................................................... 5-7
Addressing Mode
............................................................................................ 5-7
Disc Sparing
................................................................................................. 5-7
Sector Sparing
............................................................................................ 5-7
Track Sparing ............................................................................................. 5-8
Controller PCA-A6 .......................................................................................... 5-8
Servo System ................................................................................................ 5-11
Head-Disc Assembly A3 ................................................................................. 5-12
Dedicated Servo Code
................................................................................ 5-12
Sampled Servo Code
.................................................................................. 5-13
Servo Head
.......................................................................................... 5-13
Servo Read Preamplifier/Write Driver IC
........................................................... .5-13
Drive ID Circuit
...................................................................................... 5-13
Head Gain Reference PROM and DAC
.............................................................. 5-14
Actuator ..................................................... ~ .. ~ ....................................... 5-14
Speed Sensor .......................................................................................... 5-14
Read/Write PCA-A2 ..................................................................................... 5-14
Dedicated Servo AGC Amplifier.
.................................................................... 5-14
Sampled Servo Switch
................................................................................ 5-15
Sampled Servo AGC Amplifier
....................................................................... 5-15
Servo PCA-Al
........................................................................................... 5-15
Servo Controller
...................................................................................... 5-15
2-Bit ADC
............................................................................................ 5-16
Dedicated Servo AGC Circuit.
....................................................................... 5-17
Sampled Servo AGC Circuit
.......................................................................... 5-17
Sector Mark Decoder
................................................................................. 5-17
Dedicated Servo Circuit
.............................................................................. 5-17
Sampled Servo Circuit
................................................................................ 5-19
8

Contents (continued)
Sampled/Dedicated Select Switch ................................................................... .5-20
Slew Rate Limiter
.................................................................................... 5-20
Slew Rate Limit Switch
.............................................................................. 5-20
Off-Track Detector ................................................................................... 5-20
Track Crossing Detector .................................................................. " ........... 5-20
Fault Latches .......................................................................................... 5-21
Servo Power Amplifier ................................................................... " ........... 5-21
Amplifier Error Detection ............................................................... , ........... 5-24
Servo System Errors ..................................................................................... 5-25
Track Follower -PLL Errors
......................................................................... 5-25
Seek Errors ............................. " ............................................................. 5-26
Power Amplifier Error ................. , ............................................................. 5-26
Error ReIlOrting ........................ " ............................................................. 5-27
Flowcharts .... " .......... , .................... " ............................................................. 5-27
Read/Write System ........................... , ............................................................. 5-27
Head-Disc Assembly
A3 ................................................................................. 5-28
Recording Medil.lm ..................... , ............................................................. 5-28
Read/~'rite Heads .................................................................................... 5-28
Read Preamplifier/Write Driver ICs ... , ............................................................ .5-28
Read/Write PCA-A2 ..................................................................................... 5-29
Read/~rrite Controller IC ............................................................................ 5-29
Head Select Encoder
................................................................................. 5-32
Read Chain
........................................................................................... 5-32
Write Chain
.......................................................................................... 5-33
Read/~rrite System Errors ............................................................................ 5-33
Error Reporting
...................................................................................... 5-34
Spindle Drive System ....... , ............................................................................... 5-34
AC Input (:ircuit ........ , ............................................................................... 5-35
Spindle Motor BI ........................................................................................ 5-35
Primary Power PCA-A8 ................................................................................. 5-35
LINE- Switch ........................................................................................ 5-35
Start Capacitor and Relay ............................................................................ 5-35
Brake V'oltage Source
................................................................................. 5-36
Speed Sensor ............................................................................................. 5-36
Servo PCA-/\1 ........................................................................................... 5-36
Read/Write PCA-A2
..................................................................................... 5-36
Power Distribution PCA-A5 ............................................................................. 5-36
Power Sl.lpply System ....................................................................................... 5-36
AC Input Circuit
........................................................................................ 5-36
Primary Power PCA-A8 ................................................................................. 5-37
Power Supply PCA-A4 .................................................................................. 5-37
Primary Power Selection ............................................................................. 5-37
Primary Control Circuit .............................................................................. 5-37
Output Section ........................................................................................ 5-37
Fault Detection and Protection
...................................................................... 5-37
Power Distribution PCA-A5 ............................................................................. 5-37
Read/Write PCA-A2 ..................................................................................... 5-37
Servo PCA-,I\'] .......................................................................................... 5-38
9

Contents (continued)
LED Display ............................................................................................. 5-38
HDA Air Filtration
......................................................................................... 5-38
Recirculating Filter
...................................................................................... 5-38
Breather Filter
........................................................................................... 5-38
Chemical Filter and Desiccant Chamber
................................................................ 5-38
Drive Air Flow ............................................................................................. 5-38
Chapter 6 Page
6-1 Removal And Replacement
Introduction
................................................................................................. 6-1
Tools Required .............................................................................................. 6-1
Illustrations .................................................................................................. 6-2
Drive Preparation
For Service ............................................................................... 6-2
Drive Removal And Replacement Procedures
............................................................... 6-2
Rear Cover
............................................................................................... 6-2
HP-IB Assembly
.......................................................................................... 6-2
Front Panel ............................................................................................... 6-3
Front Cover .............................................................................................. 6-3
Controller PCA-A6
....................................................................................... 6-3
EPROM Kit, Controller PCA-A6 ......................................................................... 6-3
Read/Write PCA-A2
...................................................................................... 6-4
Servo PCA-AI ............................................................................................ 6-4
Power Distribution PCA-A5 .............................................................................. 6-4
Line Filter AssemblyFL1 ................................................................................. 6-4
Drive Belt, Motor Pulley
................................................................................. 6-5
Power Supply PCA-A4
................................................................................... 6-5
Primary Power PCA-A8
.................................................................................. 6-6
Start Capacitor Cl ........................................................................................ 6-6
Motor BI ................................................................................................. 6-7
Head-Disc Assembly
A3 .................................................................................. 6-7
Chapter 7
Adjustments Page
7-1
Introduction ............................................................................................. , ... 7-1
Chapter 8
Troubleshooting and Diagnostics Page
8-1
Introduction ................................................................................................. 8-1
Safety Considerations ........................................................................................ 8-1
10

Contents (continued)
Troubleshooting Strategy ................................................................................... 8-1
Self-Test Diagnostics ......................................................................................... 8-1
Diagnostic Switch ......................................................................................... 8-2
Run Time Mode ....................................................................................... 8-2
Diagnostic Mode ...................................................................................... 8-2
LED Disp]ay .............................................................................................. 8-3
Assembly Id.entification .................................................................................. 8-3
CS/80 External Exerciser .................................................................................... 8-3
Error Logs ................................................................................................... 8-4
Error Rate 'fest (ERT) Log ............................................................................... 8-4
Run Time Log ............................................................................................ 8-4
Fault Log ................................................................................................. 8-5
Error Codes .................................................................................................. 8-5
TERRORS ................................................................................................ 8-6
DERRORS ................................................................................................ 8-6
Servo Controller Error Codes ............................................................................ 8-6
Data Error Troubleshooting ................................................................................. 8-7
Checking Power Supply Voltages ............................................................................ 8-7
Servo Test Point PCA ....................................................................................... 8-8
Read/Write Test Point PCA ................................................................................. 8-8
Chapter 9
Replaceable Parts
Page
9-1
Introduction ................................................................................................. 9-1
Ordering Information ........................................................................................ 9-1
Service Kit Contents ......................................................................................... 9-2
Chapter 10
Reference Page
10-1
Controller PCi\-A6 ......................................................................................... 10-1
Chapter 11
Product History Page
11-1
Introduction ................................................................................................ 11-1
11

Contents (continued)
Chapter 12
Diagrams Page
12-1
Introduction ................................................................................................ 12-1
Dimensions .................................................................................................. 12-1
Air Circulation................................................................... - ....................... 12-1
Assembly Location .......................................................................................... 12-1
Signal Distribution .......................................................................................... 12-1
Functional Block Diagrams ................................................................................. 12-2
Appendix A
HP-IB Controller Page
A-I
Introduction
................................................................................................ A-I
Controller Interfaces ........................................................................................ A-I
HP-IB .................................................................................................... A-I
HP-IB Communications .............................................................................. A-3
Channel Management ................................................................................ A-4
Message Structure .................................................................................... A-4
CS/80 Instruction Set ................................................................................. A-4
ESI ....................................................................................................... A-5
Disc Data Bus ........................................................................................ A-5
Data Path Control Bus ............................................................................... A-6
Servo Control Bus .................................................................................... A-7
Miscellaneous Signals ................................................................................. A-7
Human Interface
........................................................................................ A-7
Functional Operation ....................................................................................... A-7
Power-Up ................................................................................................ A-8
Head Positioning ......................................................................................... A-8
Write .................................................................................................... A-8
Read ..................................................................................................... A-9
Error Correction .................................................... " ................................... A-I0
Hardware Architecture ................................................ " ................................... A-I0
HP-IB Circuitry
..................................................... " ................................... A-I0
HP-IB Interface
...................................................................................... A-IO
DMA ................................................................................................ A-I0
ESI Circuitry ............................................................................................ A-II
Disc Data Interface .................................................................................. A-II
DMA ................................................................................................ A-ii
ECC ............................................... - .. - ................................................ A-I2
Data Path Control Interface
........................................................................ A-I2
Servo Control Interface ............................................................................. A-i2
Microprocessor Circuits
................................................................................ A-12
Microprocessor
...................................................................................... A-13
Microprocessor Memory
............................................................................ A-13
Clock Generators
.................................................................................... A-13
12

Contents (continued)
Interrupt Controller ................................................................................. A-I3
Bus Error Timer
..................................................................................... A-I3
Human Interface Circuitry ............................................................................. A-I4
HP-IB Address/Selftest Switch
...................................................................... A-I4
LED Drivers ......................................................................................... A-I4
Firmware Architecture .................................................................................... A-I4
Drive Initialization Firmware
........................................................................... A-I4
Multi-Tasking Executive
................................................................................ A-I6
Channel Module
........................................................................................ A-I6
Command Preprocessor ................................................................................ A-I7
CS/80 Module .......................................................................................... A-I7
RPS Task ................................................................................................ A-I7
Error Correction Task .................................................................................. A-I8
Diagnostics .................................................................................................. A-I8
Disc Caching ............................................................................................... A-I8
Cache Functional Operation ............................................................................ A-I8
Read With Disc Caching ............................................................................ A-I8
Write With Disc Caching ............................................................................ A-I9
Cache Flushing
...................................................................................... A-I9
Cache Hardware ........................................................................................ A-I9
Cache Diagnostics
...................................................................................... A-20
13

Figures and Tables
Figure or Table Page
Figure
1-1. liP 7937 Disc Drives in HP 19511A Cabinet .................................................... 1-3
Figure 3-1. Drive Controls. Connectors, and Indicators ..................................................... 3-6
Figure
3-2. Rear Panel Label Locations ..................................................................... 3-7
Figure
3-3. Maximum Cable Length for HP-IB Channel. ................................................... 3-8
Figure 5-1. Track Format, Logical Vs Physical Addressisng ................................................. 5-4
Figure
5-2. Maintenance Tracks ............................................................................. 5-5
Figure
5-3. Sector Format ........................................................................... ~ ........ 5-6
Figure
5-4. Addressing Strllcture ............................................................................ 5-9
Figure
5-5. Spare Track Scalar Values ...................................................................... 5-10
Figure 5-6. Servo Controller Power On Flowchart. ........................................................ 5-39
Figllre
5-7. Recalibrate Flowchart ......................................................................... 5-41
Figure 5-8. Seek Flowchart ................................................................................. 5-42
Figure
5-9. Bump Seek Flowchart .......................................................................... 5-44
Figure
5-10. Servo Commands Flowchart .................................................................. 5-45
Figure
5-11. Controller Power On Flowchart .............................................................. 5-46
Figure
5-12. Dedicated Servo Code ....................................................................... .5-71
Figure
5-13. Sampled Servo Code .......................................................................... 5-73
Figure
5-14. Dedicated Servo Circuit Timing .............................................................. 5-75
Figure
5-15. Sampled Servo Circuit Timing ................................................................ 5-77
Figure
5-16. Disc Drive Basic Block Diagram .............................................................. 5-79
Figure
6-1. Spring-Type Spindle Lock ....................................................................... 6-9
Figure
6-2. Bracket-Type Spindle Lock ..................................................................... 6-9
Figure
8-1. ERT Log Error Code Byte ...................................................................... 8-9
Figure
8-2. Run Time Log Error Code Byte ................................................................ 8-9
Figure
8-3. Power Supply PCA-A4 Outputs ................................................................ 8-10
Figure 8-4. Servo System Test Point PCA .................................................................. 8-40
Figure 8-5. Read/Write Test Point PCA ................................................................... 8-45
Figure
9-1. Disc Drive, Exploded View ..................................................................... 9-7
Figure
9-2. HP 19511A Cabinet, Exploded View ............................................................ 9-9
Figure
9-3. HP 19512A Rack Slide Kit, Exploded View ................................................... 9-11
Figure 12-1. Drive Dimensions ........................................................................... 12-10
Figure 12-2. HP 19511A Cabinet Dimensions ............................................................ 12-11
Figure 12-3. Airflow Within Drive ....................................................................... 12-12
Figure
12-4. Location of Assemblies and Parts ........................................................... 12-13
Figure
12-5. Primary Power Cable Assembly WI ........................................................ 12-14
Figure
12-6. Power Supply Input Cable Assembly W3 ................................................... 12-15
Figure
12-7. Power Supply Output Cable Assembly W4 ................................................. 12-16
Figure
12-8. Speed Sensor Cable Assembly W5 .......................................................... 12-17
Figure
12-9. Power Jumper Cable Assembly W6 ......................................................... 12-18
Figure
12-10. Signal Jumper Cable Assembly W7 ........................................................ 12-19
Figure
12-11. HDA Cable Assembly W8 ................................................................. 12-20
Figure 12-12. Cabling Diagram ........................................................................... 12-21
Figure 12-13. Servo PCA-Al, Parts Location and Connector Pinout .................................... 12-23
Figure
12-14. R/W PCA-A2, Parts Location and Connector Pinout. .................................... 12-25
Figure
12-15. HDA Assembly A3, Parts Location and Connector Pinout ................................ 12-27
Figure
12-16. Power Supply PCA-A4. Parts Location and Connector Pinout. ........................... 12-29
14

Figures and Tables (continued)
Figure 12-17. Power Distribution PCA-AS, Parts Location and Connector Pinout ...................... 12-31
Figure 12-18. LED PCA-A 7, Parts Location and Connector Pinout ..................................... 12-32
Figure 12-19. Primary Power PCA-A8, Parts Location and Connector Pinout .......................... 12-33
Figure
12-20. Servo System, Functional Block Diagram .................................................. 12-35
Figure 12-21. Read/Write System, Functional Block Diagram ........................................... 12-39
Figure
12-22. Spindle Drive System, Functional Block Diagram ......................................... 12-41
Figure 12-23. Power Supply System, Functional Block Diagram ......................................... 12-43
Figure A-I. HP-IB Signal Lines
............................................................................. A-2
Figure A-2. Firmware Architecture ....................................................................... A-IS
Figure A-3. HP-IB Controller PCA-A6 Functional Block Diagram ....................................... A-21
Figure A-4. HP-IB Controller PCA-A6, Parts Location and Connector Pinout ........................... A-23
Table
1-1. Disc Drive, Product Structure .................................................................... 1-4
Table 5-1. List of Mnemonics .............................................................................. 5-48
Table 8-1. External Exerciser Commands .................................................................. 8-11
Table 8-2. List of DERROR/TERRORS ................................................................... 8-15
Table
8-3. Servo System Test Connector Al]3, Mnemonics ................................................ 8-41
Table 8-4. Read/Write System Test Fixture, Mnemonics ................................................... 8-46
Table
9-1. Disc Drive, Replaceable Parts .................................................................... 9-3
Table 9-2. HP 1951lA Cabinet, Replaceable Parts .......................................................... 9-8
Table 9-3. HP 19512A Rack Slide Kit, Replaceable Parts .................................................. 9-10
Table
9-4. Abbreviations ................................................................................... 9-12
Table 9-5. Code List Of Manufacturers .................................................................... 9-13
Table
12-1. Signal Distribution List ........................................................................ 12-3
Table 12-2. Voltage Distribution List ..................................................................... .12-9
Table A-I. HP-IB Definitions
.............................................................................. A-3
Table
A-2. Universal Command Formats .................................................................. A-3
Table
A-3. HP-IB Message Structure ....................................................................... A-5
Table A-4. Supported CS/80 Commands ................................................................... A-6
15

Product Information
1-1. INTRODUCTION
This chapter contains product information for the
Hewlett-Packard Model 7936 and 7937 Disc
Drives. The information provided includes a
general description
of the HP 7936 and HP 7937, a
list of equipment supplied, details of the product
structure, test equipment required, and support
strategy.
1-2. PRODUCT DESCRIPTION
The HP 7936 and HP 7937 Disc Drives are high-
performance, random access, data storage devices
designed for use with medium- and large-sized
computer systems. In this manual, unless otherwise
specified, "drive" refers
to both the HP 7936 and
HP 7937.
A microprocessor-based controller is factory-
installed in the drive
to provide an interface to the
host computer.
Two HP-IB controllers are avail-
able
for this purpose. In the HP 7936H and HP
7937H Disc Drives, interface to the host is via an
Hewlett-Packard Interface
Bus (HP-IB) controller.
In the HP 7936XP and HP 7937XP, the controller
has HP-IB Cache added. Both
of the controllers
interface with the drive electronics via an
HP-developed standard interface (ESI).
A sealed head-disc assembly (HOA) in the drive
contains a spindle with a stack
of seven non-
removable 210-millimetre (8.3-inch) diameter
discs.
The spindle is belt-driven by a motor mounted ad-
jacent
to the sealed HOA. There are seven (HP
7936) or 13 (HP 7937) thin-film surfaces on the
discs for data storage. An additional surface is used
for dedicated servo code.
The formatted storage capacity
of the drive is 307
megabytes (HP 7936) or 571 megabytes (HP 7937).
Each data surface uses a movable read/write head
to service its data tracks. The bottom surface of
the lowest disc in the stack contains prerecorded
servo code which
is used to position the read/write
heads over the desired data track.
1
Head positioning is performed by a rotary actuator
and a dual closed-loop servo positioning system.
Control
of the servo system is derived from the
dedicated servo code on the servo surface and also
from servo code embedded between data sectors
on all of the data surfaces.
Mechanical and contamination protection
for the
discs, heads, and rotary actuator
is achieved by
enclosing these components in the sealed head-disc
assembly. The head-disc assembly includes a self-
contained air filtration system which supplies clean
air and equalizes temperature throughout the
HOA.
A self-contained power supply in the drive supplies
dc voltages to the controller and the drive
electronics. The standard drive
is configured for
operation from a 90-132V, 60 Hz power source.
Options 015 and 017 permit operation from 50 Hz
and 180-264V, respectively.
The drive is contained in an enclosed housing and
is fitted with removable covers to permit easy ac-
cess for servicing. A total
of two drives can be in-
stalled on the rack slides of a desk-height HP
1951lA Cabinet. See figure 1-1. An HP 19512A
Rack Slide Kit
is available for mounting the drive
in an EIA 19-inch rack cabinet. A special lifter
tool makes it possible
for one person to install the
56.7 kg (125 lb) drive in either cabinet.
...
An upgrade kit is available for the drive: HP
97521A Controller Cache Upgrade.
Self-test diagnostics and a fault-finding system
contained within the drive exercise key functions
of its operation. Self test is performed automati-
cally
at power on and also can be initiated by the
host. Drive status is indicated by three light-
emitting diodes (LEOs)
on the front panel. See
figure 3-1. In the event of a self-test failure, the
LEOs will identify the failed subassembly in the
drive.
1-1

Product Information
7936 and 7937
1-3. DOCUMENTATION SUPPLIED
The drive is supplied with one each of the follow-
ing publications:
• H P 7936 and H P 7937 Disc DrivC.'s
Operating and Installation Manual, part no.
07937-90902
• Site Environmental Requirements lor
Disc/Tape Drives Manual, part no. 5955-3456
1-4. SUPPORTING DOCUMENTATION
The following supporting documentation for the
drive may be ordered from your nearest
Hewlett-Packard Sales and Support Office:
• HP 7936 and HP 7937
Hardware
Support Manual,
07937-90903
Disc Drives
part no.
• CS/80 Instruction Set Programming Manual,
part no. 5955-3442
• CS/80 External Exerciser Manual, part no.
5955-3462
1-5. PRODUCT STRUCTURE
The drive product structure is outlined in Table
1-1.
1-6. SPECIFICATIONS
Specifications for the drive are listed in the Site
Environmental Requirements
lor Disc/Tape Drives
Manual,
part no. 5955-3456. This manual is sup-
plied with the drive.
1-7. SERIAL NUMBER
The serial number of the drive is recorded on a
serial number label attached
to the front cover of
the drive, below the front panel. The drive model
1-2
number and full serial number should be quoted in
any communication with Hewlett-Packard regard-
ing the drive.
1-8. SUPPORTED EQUIPMENT
This manual is intended to provide the informa-
tion needed
to support service of the drive and all
of its accessories and options.
1-9. TEST EQUIPMENT REQUIRED
No special test equipment is needed for installation
and normal maintenance
of the drive. However,
when using the special diagnostics available
for
troubleshooting the drive, the following equipment
is needed:
• HP 85B Personal Computer
• CS/80 External Exerciser Tapes, part num-
bers 5010-0566 and 5010-0567.
• CS/80 External Exerciser Manual, part no.
5955-3462.
1-10. WARRANTY
The drive is covered by a 90-day Hewlett-Packard
warranty. However, this warranty
is voided if the
sealed head-disc assembly
is opened or otherwise
tampered with. The warranty does
not include in-
stallation
or rack mounting.
1-11. SUPPORT STRATEGY
The drive may be repaired on site to the field
replaceable assembly level. Troubleshooting
is
aided by firmware controlled self-test diagnostics
with the malfunctioning assembly identified
on a
front-panel display,
error codes returned by the
drive
to the CPU, and diagnostics available
through the use
of the HP 85B Personal Computer
and an external exerciser or a host-supported ex-
ternal exerciser.