CORVUS 7100-04702 User manual

THE CORVUS SERVICE MANUAL
Floppy Disk Drive
**. CORVUS SYSTEMS
* •

DISCLAIMER OF ALL WARRANTIES &LIABILITIES
Corvus Systems, Inc. makes no warranties, either expressed or implied, with respect to this
manual or with respect to the software described in this manual, its quality, performance, mer-
chantability, or fitness for any particular purpose. Corvus Systems, Inc. software is sold or
licensed lias is:' The entire risk as to its quality or performance is with the buyer and not Corvus
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servicing, repair, or correction and any incidental or consequential damages. In no event will
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Corvus Systems, Inc. has been advised of the possibility of such damages. Some states do not
consequential damages, so the above limitation may not apply to you.
Every effort has been made to insure that this manual accurately documents the operation and
servicing of Corvus products. However, due to the ongoing modification and update of the soft-
ware along with future products, Corvus Systems, Inc. cannot guarantee the accuracy of printed
material after the date of publication, nor can Corvus Systems, Inc. accept responsibility for
errors or omissions.
NOTICE
Corvus Systems, Inc. reserves the right to make changes in the product described in this man-
ual at any time without notice. Revised manuals and update sheets will be published as needed
and may be purchased by writing to:
Corvus Systems, Inc.
2029 O'Toole Avenue
San Jose, CA 95131
Telephone: [phone]
TWX 910-338-0226
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ment may not, in whole or in part be copied, photocopied, reproduced, translated or reduced to
any electronic medium or machine readable form without prior consent, in writing, from
Corvus Systems, Inc.
Copyright© 1982 by Corvus Systems, Inc. All rights reserved.
Mirror® patent pending, The Corvus Concept,"" Transporter,"" Corvus OMNINET,TM Corvus
Logicalc,"" Time Travel Editing,"" EdWord,"" Constellation,"" Corvus,"" Corvus Systems,"" Personal
Workstation,"" Tap Box,"" Passive Tap Box,"" Active Junction Box,"" Omninet Unit"" are trademarks
of Corvus Systems, Inc.
FCC WARNING
This equipment generates, uses, and can radiate radio frequency energy and if not installed and
used in accordance with the instruction manual, may cause interference to radio communica-
tions. As temporarily permitted by regulation it has not been tested for compliance with the
limits for Class A computing devices pursuant to Subpart Jof Part 15 of FCC Rules, which are
designed to provide reasonable protection against such interference. Operation of this equip-
ment in aresidential area is likely to cause interference in which case the user at his own
expense will be required to take whatever measures may be required to correct the interference.

CORVUS DEALER SERVICE
CORVUS SYSTEMS
CONCEPT PERSONAL WORKSTATION
8" FLOPPY DRIVE
SERVICE MANUAL
PART NO.: 7100-04702
DOCUMENT NO.: CCC/12-01/1.1
RELEASE DATE:
JULY 10, 1983
This document contains three types of notations. These are, in increasing order of importance, NOTE,
CAUTION, and WARNING. The NOTE indicates some action to be taken to speed or simplify a
procedure.
The CAUTION indicates that potential damage to the equipment or user data exists, and
care should be taken to avoid this. The WARNING indicates that potential harm or injury to the
service technicion or operator exists, and extreme care should be taken to avoid these.

CORVUS DEALER SERVICE
TABLE OF CONTENTS

CORVUS DEALER SERVICE
TABLE OF CONTENTS
List of Figures iii
List of Assembly Drawings and Schematics .......................................................... .. IV
Drive Specifications V
CHAPTER 1 - OVERVIEW
1.0 Scope of Manual. ............................................................. .. .......... .. 1
1.1
General Description. ...................................................................... .. 1
1.1.1 Drive
Assembly. ...................................... .. ........................ .. 1
1.1.2 Interface
Description. ............................................................ .. 1
1.2 Diskettes ................................. .. 1
1.2.1 Care and Handling of Diskettes 1
CHAPTER 2 - FUNCTIONAL DESCRIPTION
2.0 Scope of C:hapter ......................................................................... .. 3
2.1 Drive Mechanism. ........................................................................ .. 3
2.2 Block Diagram Description. .............. .. .............. .. ................... .. ........... .. 3
2.2.1 Index Pulse ..... ................................................................ .. 3
2.2.2 Drive Status Logic. .............................................................. .. 3
2.2.3 Spindle Drive Control. ...................... .. ................................... .. 3
2.2.4 Carriage Positioner Control 4
2.2.5 Write/Erase Control 4
2.2.6 Read Amplifier and Digitizer. ..................................................... .. 6
2.3 Concept Interface. ........................................................................ .. 7
CHAPTER 3 - DISASSEMBLY AND ASSEMBLY PROCEDURES
3.0 Scope of C:hapter ......................................................................... .. 9
3.1 Cover Disassembly and Assembly 9
3.2 :Power Supply Removal 10
3.3 :Power Harness Removal 10
3.4 :Rear ConIlectors and Devices 10
CHAPTER 4 - CHECKS AND ADJUSTMENTS
4.0 Scope of C:hapter 12
4.1 List of Tools 12
4.2 Drive Adjustments 12
4.2.1 Spindle Drive Motor -................................................. .. 12
4.2.2 Cats Eye Alignment 13
4.2.3 Head Carriage Adjustment 15
4.2.4 Index Sensor Checks and Adjustments 15
4.2.4.1 Index-To-Data Burst Check 15
4.2.4.2 Index Sensor Adjustment 16
4.2.4.3 Index Pulse Width Check 17
4.2.5 Track Zero Sensor Check and Adjustment 18
4.2.6 Amplitude Check 19
4.2.7 Azimith Check 20
4.2.8 Load Arm Adjustment 21

CORVUS DEALER SERVICE
4.3 Interface Controller Checks and Adjustments 21
4.3.1 Bias Voltage
Adjustment 22
4.3.2 Range Adjustment 22
4.3.3 Pre com p 22
4.4 Power Supply Adjustments ~ ~ 23
CHAPTER 5 - TROUBLESHOOTING
5.0 Scope of Chapter 24
5.1 Diagnostics 24
5.1.1 Operation 24
5.1.2 Test Descriptions 24
5.2 System Level Troubleshooting. ............................................................. .. 25
5.2.1 Interface Controller and Cable 26
5.2.2 Floppy Drive 26
5.2.3 Concept Workstation 26
5.3 Floppy Drive Unit 26
5.3.1 Power Supply 26
5.3.2 Diskette Drive Unit 27
5.3.3 Power Harness ; 27
5.4 Interface Controller Card 27
5.5 Troubleshooting Guide .................................................................... .. 28
APPENDICES
Appendix A
Appendix B
Appendix C
Appendix D
Glossary. ........................................................................ .. 30
Part Numbers .................................................................... .. 31
Schematic Diagrams 32
Assembly Drawings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 38
ii

CORVUS DEALER SERVICE
LIST OF FIGURES

CORVUS DEALER SERVICE
LIST OF FIGURES
2-1 FunctioIlal Block Diagram 4
2-2 FM Recording Magnetization Profiles. .......................................... .. . . . . . . . . . .. 5
2-3 Write Operation Timing Diagram 6
2-4 Read Timing Diagram. . . . . . . . . . . .. . . . . . . . . . . .. ........................................... .. 7
3-1 Cover Installation 9
3-2 Drive Power Connector 10
3-3 Left Cover 11
4-1 Drive Circuit Board Assembly, Test Points 13
4-2 Hub Center Line and Track Locations 13
4-3 Cats Eye Pattern 14
4-4 Head Module Retaining and Cam Screws 15
4-5 Index-to-Data Burst 16
4-6 Index Sensor Retaining Screws and Adjustment ............................................. .. 17
4-7 Negative Going Pulse Width . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 18
4-8 Track 00 Sensor Adjustment .............................................................. .. 18
4-9 Optimum Head Azimuth Alignment 20
4-10 Head Azimuth Acceptable Lower Limit 20
4-11 Head Azimuth Acceptable Upper Limit "21
4-12 Load
Arm Adjustment, Front View 21
4-13 Interface Controller Card 22
4-14 Power Supply Adjustments 23
5-1 Floppy [)rive Installation 25
5-2 Interface Controller Installation 26
iii

CORVUS DEALER SERVICE
LIST OF ASSEMBLY DRAWINGS AND SCHEMATICS

CORVUS DEALER SERVICE
'LIST OF ASSEMBLY DRAWINGS AND SCHEMATICS
Drive Schematics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 32
Controller Schematic 37
Assembly Drawings
Mechanism. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 38
Power Supply. ................................................................................... .. 39
Left Cover 0••••••••••••••••••••••••••••••••••••••• •• 40
DC Cable 41
Logic Board 42
Floppy Controller 43
iv

CORVUS DEALER SERVICE
SPECIFICATI()NS

CORVUS DEALER SERVICE
DRIVE SPECIFICATIONS
Tandon Model TM848-01
MECHANICAL
Height:
Width:
Length:
Weight:
ELECTRICAL
+5 VDC Power:
+24 VDC Power:
Start Current
ENVIRONMENTAL
Operating Temperature:
Storage Temperature:
Wet Bulb Temperature:
Noncondensing Operating Humidity:
RELIABILITY
MTBF
MTTR
Error Rate:
Soft Read:
Hard Read:
Seek Errors:
PERFORMANCE
Head Wear Guarantee:
Number of Tracks:
Track
to track access time:
Head Settling Time:
Average Access Time, including head settling:
Motor Start Time:
Disk Rotational Speed
Instantaneous Speed Variation:
Flux
Changes per inch, inside track:
Transfer Rate:
Unformatted Recording Capacity:
IBM
Format Recording Capacity:
Recording Method:
v
2.30 inches
8inches
13.125 inches
6
pounds with power supply
+5 volts ±5%, 0.75 amp typical
+24
vo~ts ±10%, 0.92 amp typical
2.5
amps, 400 msec on 24 volts
4.4°C to 46°C
-40°C to 71°C
26°C
maximum
20% to 80%
10,000
power-on hours
30 minutes
1 in 109bits
1
in 10
12
bits
1in 106seeks
15,000 media
hours
77
3milliseconds
15 milliseconds
91 milliseconds
0.5 seconds
maximum
360 RPM
±1.0%
6536 FCI
250K BPS
0.4
MBytes
0.3 MBytes
FM

CORVUS DEALER SERVICE
CHAPTER 1
OVERVIEW

CORVUS DEALER SERVICE
CHAPTER 1
OVERVIEW
1.0 Scope of Manual
This manual is designed for service technicians who perform maintenance or warranty service on the Corvus Floppy
Disk
Drive and the interface. A troubleshooting guide is included which will direct the technician to the appropriate
procedure. Except for the power supply, the internal parts of the drive are not replaceable. In such cases, the drive
should be returned to Corvus via a Return Merchandise Authorization (RMA).
All
information in this manual applies to the single-sided, single-density drive only. Subsequent models will be covered
in a separate manual or addendum.
This first chapter will briefly describe the drive, the interface, and the diskettes.
1.1 General Description
The Corvus Floppy Disk Drive provides an additional data storage and boot device for the Corvus Concept Personal
Workstation. The floppy is aSingle-sided, single-density drive which uses eight-inch standard floppy diskettes. The
interface is composed of asingle Interface Controller Card and acable. The card plugs into slot three of the Concept
base unit.
1.1.1 Drive Assembly
The mechanism and internal electronics are manufactured by Tandon Corporation™. The power supplyis provided by
Corvus Systems and is incorporated in the drive cabinet.
All electronic
components of the drive are mounted on asingle circuit board located in the drive's chassis. At the rear of
the drive cabinet is the power receptacle, fuse holder, on/off switch, and interface connectors. The power supply is
mounted to the floppy chassis assembly.
1.1.2 Interface Description
The floppy interface is composed of an Interface Controller Card and afifty-pin flat ribbon cable. Some drives use a
fifty-pin
twisted pair cable, which is acceptable. The Controller uses an intelligent Floppy Controller chip and
associatedcircuits. Data transfers between the drive and the Controller are in the form of raw serial data (clock pulses
included).
Data transfers between the Controller and the Concept are eight-bit parallel.
The Interface Controller Card has three adjustment potentiometers: bias voltage, range, and precomp adjust. These
adjustments will be covered in Chapter Four.
1.2 Diskettes
The floppy operates with standard eight-inch, single-sided, single density, soft-sectored diskettes.
For
diskette insertion, operator access is provided via a slot located on the front of the drive. The Diskette Lever must
be turned counterclockwise, to the straight-up position, for diskette loading. Once the diskette is fully inserted, the
diskette lever is turned clockwise, until perpendicular with the door, and the diskette is now loaded.
The floppy drive is equipped with aWrite Protect Sensor. This sensor operates in conjunction with the diskette which
has aslot cut in the protective jacket. When the slot is UNCOVERED, the diskette is write PROTECTED. The slot
must be covered to write on the diskette.
1.2.1 Care and Handling of Diskettes
It is important that the diskette be cared for, handled, and stored properly so that the integrity of the recorded data is
maintained. A damaged or contaminated diskette can impair or prevent recovery of data, and can result in damage to
the read/write heads of the drive.
T1'Tandon is a trademark of Tandon Corporation
1

Overview
CORVUS DEALER SERVICE
Following these guide lines will increase diskette reliability and extend the life of the diskettes:
1) Keep the diskettes away from magnetic fields. Don't place diskettes on televisions or monitors.
2) Keep diskettes in their protective jackets when not in use. Never touch the precision surface of the diskettes.
3) Do not bend or fold the diskettes. Be careful when inserting them into the drive.
4) Store diskettes at room temperatures in a covered container away from contamination such as smoke or spilled
liquids.
5) REMOVE DISKETTES BEFORE POWERING ON OR OFF THE DRIVE. Random spikes during power on or off
can cause noise to be written on the diskette and render it unusable.
Floppy
diskettes have an operating life of about 40 hours. This time varies depending on environment and usage. It is
recommended that back-up copies of all valuable data be kept in asafe place.
2

CORVUS DEALER SERVICE
CHAPTER 2
FUNCTIONAL DESCRIPTION

CORVUS DEALER SERVICE
Functional Description
CHAPTER 2
FUNCTIONAL DESCRIPTION
2.0 Scope of Chapter
This chapter will describe the functional operation of the Drive Mechanism, Drive Electronics, and Interface
Controller. The electronics will be presented at ablock diagram level.
2.1 Drive Mechanism
The drive consists of aspindle drive system, a head positioning system, and a read/write/erase system.
The diskette is accurately positioned when inserted by plasticguides. The position is ensured by the backstop and disk
ejector.
Closing the diskette lever activates the cone and clamp system, resulting in centering of the diskette and
clamping of the diskette to the drive hub. The drive hub is driven at a constant speed of 360 RPM by a servo-controlled
brushless DC motor. The head is loaded into contact with the recording medium whenever the diskette lever is latched.
The head is positioned over the desired track by means of a stepper motor and band assembly and its associated
electronics.
The stepper motor rotates 3.6 degrees to cause a one-track linear movement. When a write-protected
diskette is inserted into the drive, the Write Protect Sensor disables the write electronics of the drive, and aWrite
Protect status output signal is available to the interface.
When performing a write operation, a0.013-inch wide (nominal) data track is recorded. This track is then tunnel erased
to 0.012 inch (nominal). Tunnel erasing helps prevent crosstalk between tracks by erasing the outer edges and
increasing the space between the tracks.
Data recovery electronics include alow-level head amplifier, adifferentiator, a zero crossing detector, and digitizing
circuits.
In addition, the drive has the following sensors:
1. A track 00 sensor that senses when the Head Carriage Assembly is positioned at Track 00.
2. The two index sensors, each of which consists of an LED light source and a phototransistor.
3. The Write Protect sensor disables the write electronics whenever the write-enable tab is removed from the
diskette.
Carriage Position Control
Write/Erase Control
Read Amplifier and Digitizer
4)
5)
6)
2.2 Block Diagram Description
Figure 2-1 is a functional block diagram of the drive. It should be referred to in conjunction with the following sections.
The drive consists of six functional groups:
1) Index Pulse Shaper
2) Drive Status Logic
3) Spindle Drive Control
2.2.1 Index Pulse
An index pulse is provided to the Controller via the index pulse interface line. The index circuitry consists of an index
LED, a
phototransistor, and a pulse shaping network. As the index hole in the disk passes an index LED-
phototransistor, light from the LED strikes the phototransistor, causing it to conduct. The signal from the index
phototransistor is passed on to the pulse shaping network, which produces a pulse for each hole detected. This pulse is
presented on the index pulse interface line.
2.2.2 Drive Status Logic
There are five status logic lines: Write Protect, Track 00 Sensor, Two-Sided Disk, Ready, Disk Change (see section 2.3).
2.2.3 Spindle Drive Control
The spindle drive system consists of aspindle assembly driven through adrive belt by a brushless DC
motor/tachometer. The servo electronics are located on the printed circuit board.
3

Functional Description
CORVUS DEALER SERVICE
Figure
2-1. Functional Block Diagram
The control circuitry contains an interface control line. When the drive motor control interface line is false (high), the
drive motor is allowed to come up to speed.
2.2.4 Carriage Positioner Control
The head positioning system uses a bipolar-driven motor drive, which changes one phase for each track advancement
of the read/write carriage. In addition to the logic necessary for motor control, a gate is provided that inhibits positioner
motion during a write operation.
2.2.5 Write/Erase Control
Information is recorded on the diskette by using a double-frequency code. Figure 2-2 illustrates the magnetization
profiles in each bit cell for the number sequence shown for FM recording.
4

CORVUS DEALER SERVICE
........, BIT CELL ,.......
I1I1
BIT PATTERN II
WRITE DATA II
Figure 2-2. FM Recording Magnetization Profiles
Functional Description
All signals required to control the electronics are provided by the Interface Controller Card in the Concept. These
control signals are:
•Select
•Write
Gate
•Write Data
•Write Current
Composite Read Data is sent to the Controller via the interface.
The write electronics consist of a switchable write current source, a write waveform generator, an erase current
source, the trim erase control logic, and the head selection logic.
The read/write winding on the head is centertapped. During a write operation, current from the write current source
flows in alternate halves of the winding, under control of the write waveform generator.
The condition required for recording, Le., Drive Ready, must be established by the Interface Controller as follows:
1. Drive speed stabilization occurs 500 milliseconds after the drive motor is started.
2. Subsequent to any read/write operation, the positioner must be allowed to settle. This requires 18 milliseconds
maximum after the last step pulse is initiated, i.e., 3milliseconds for the step motion and 15 milliseconds for
settling.
3. The foregoing operations can be overlapped, if required.
Figure 2-3 illustrates the timing diagram for a write operation. At t=O, when the unit is ready, the write gate interface
line goes true. This enables the write current source. Write current is switched via the write current switch interface
line to a lower value by the Interface Controller at track 43.
The Trim Erase control goes true 190 microseconds after the Write Enable interface line since the trim erase gaps are
behind the read/write gap. It should be noted that this value is optimized between the requirements at track 00 and at
track 76, so that the effect of the trim erase gaps on previous data is minimized.
Figure 2-3 shows the information on the write data interface line and the output of the write waveform generator,
which toggles on the leading edge of every write data pulse.
5

Functional Description
CORVUS DEALER SERVICE
A
maximum of 4 microseconds between the write gate going true and the first write data pulse is only required if
faithful reproduction of the first write data transition is significant.
At the end of recording, at least one additional pulse on the write data line must be inserted after the last significant
write data pulse to avoid excessive peak shift effects.
2. UNSYCHRONIZED
3. 8.5 MA PEAK TO PEAK
4. 2 USEe MINIMUM
4 USEC MAXIMUM
I
t""'--
I
II I
1=0= 250 MILLISECONDS AFTER DRIVE MOTOR
STARTS OR 20 MILLISEOCNDS AFTER LAST STEF
PULSE,
WHICHEVER IS THE LATEST TIME.
I
Tt
NOTE 2
I
s--:...
I
... 50usec ....
I I
~-...,.. .....i~-~-~-...jI ........ H-r
...... _-+-_-i-_--t -~-"'---..a..-___lI~_4~
II
WRIET CURRENT
WRITE
WAVEFORM
GENERATOR
TRIM ERASE
INTERNAL WRIT~
BUSY
WRITE DATA
WRITE GATE
Figure 2-3. Write Operation Timing Diagram
The duration of a write operation is from the true going edge of write gate to the false going edge of erase. This is
indicated
by the internal write busy waveform shown (figure 2-3).
2.2.6 Read Amplifier and Digitizer
The Read electronics consist of:
•
Read Switch
• Read Preamplifier
•Filter
•
Differentiator
• Time Domain Filter and Digitizer
The read switch is used to isolate the read amplifier from the voltage excursion across the head during a write
operation.
The drive must be in a ready condition before reading can begin. As with the data recording operation, this ready
condition must be established by the Controller Interface.
The output signal from the read/write head is amplified by a read preamplifier and filtered by a low-pass linear phase
filter to remove noise (see figure 2-4). The linear output from the filter is passed to the differentiator, which generates
a waveform whose zero crossings correspond to the peaks of the Read signal. This signal is then fed to the zero
crossing detector and digitizer.
6