MPI 91 User manual

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PROPRIETARY NOTICE
Information contained in this manual is copyrighted,
and may not be dupl icated in ful I or in part by any
person without prior written approval from Micro
Peripherals, Inc. (MPI)
The purpose of this manual is to provide the user of
MPlls Model 91/92 and 915/925 Flexible Disk Drives
with adequately detailed documentation necessary for
efficient installation, operation, maintenance, and
ordering of spare parts for the equipment supplied.
Eve rye ff 0 r t has bee n ma de to ke ep the i n forma t ion
contained in this manual current and accurate as of
the date of publication or revision. However, no
g u a ran tee i s g i ve nor imp lie d t hat the ma n u a I
is error free, or that it is accurate with regard
to any particular specification.
Published June 1981
MICRO PERIPHERALS INC.
9754 DeeringAvenu/I
Chatsworth. California 91311
[phone]
TWX: 910-494-1213
i

TABLE OF CONTENTS
SECTION 1 GENERAL DESCRIPTION
1.1 INTRODUCTION .••.
1.2 PURPOSE OF EQUIPMENT
1.3
PHYSICAL DESCRIPTION.
1.4 FUNCTIONAL DESCRIPTION.
1.5 SPECIFICATIONS •...
1.5.1 Capacity Specifications.
1.5.2 Functional Specifications
1.5.3 Physical Specifications.
1.5.4 Reliability Specifications
SECTION 2
INSTALLATION AND CHECKOUT
2.1
INTRODUCTION • . · · · · · ·
2.2
UNPACKING
· · ·
2.3
INSTALLA TION
.
2.4
HARDWARE
·
2.5
DUST COVER
. · · · · · ·
2.6
COOLING
· . . . · · · · · ·
2.7 INPUT/OUTPUT CABLE
· ·
2.8
DC POWER
·
2.9
OPERATION
2.9.1 Flexible Diskette
Loading
2.9.2 Flexible Diskette
Removal
·
·
· · · .
·
· · ·
2.9.3
Diskette Handling Recommendations
2.10
INITIAL CHECKOUT
· · · · · · · · · .
ii
.
Page
1-1
. . . .
1-3
1-3
1-3
1-4
1-4
1-4
1-5
1-5
2-1
2-1
2-2
2-2
2-2
2-4
2-4
2-4
2-4
2-4
2-5
2-5
2-6

r •
TABLE OF CONTENTS (Continued)
SECTION 3 THEORY OF OPERATION
3.1
3.2
3.3
3.4
INTRODUCTION • • ••••
INTERFACING REQUIREMENTS •
3.2.1 Input Lines
Line Termination
Programmable Shunt
Drive
Select 1 to 4
Motor
On
Direction Select
Step
..
· ..
. ... ..... ...
·... .....
· • • .
3.2.1.1
3.2.1.2
3.2.1.3
3.2.1.4
3.2.1.5
3.2.1.6
3.2.1.7
3.2.1.8
3.2.1.9
Write Gate
Write Data . . . . ..
Side Select •
3.2.1.10 In Use (optional feature) •
3.2.2 Output Lines ·.. · . · .
3.2.2.1
3.2.2.2
3.2.2.3
3.2.2.4
Track 00
Index/Sector
Write Protect •
Read Data •
3.2.3 Connector J2
3.2.4 Connector Jl
HOW TO USE THE DRAWINGS
GENERAL DESCRIPTION
3.4.1 Head Positioning Control
3.4.2 Track ' OO Sensor •••••
· ...............
· .. • • . ....• • • • · .
· ..
. . ..............
... . .. ..... .. . . . . .
· . .. ...
iii
Page
3-1
3-2
3-2
3-2
3-2
3-3
3-3
3-3
3-3
3-3
3-3
3-6
3-6
3-6
3-6
3-6
3-7
3-7
3-7
3-7
3-9
3-9
3-10
3-11

TABLE OF CONTENTS (Cantinued)
SECTION 3 (Continued)
3.5
3.6
3.4.3
Spindle Drive Control
3.4.4
Index Sensor . . . .
3.4.5
Head Load Machanism
3.4.6
Side Selection
3.4.7
Data Recording
and Retrieving
DETAILED DESCRIPTIONS
3.5.1
Power up/Power down Logic
3.5.2
Stepper Motor Control Logic
3.5.3 Track 00 Logic . . . . ·
3.5.4
Drive Motor Control Logic
3.5.5
Index Logic
3.5.6
Head Load Logic ·
3.5.7
Side Select Logic
3.5.8
Write Protect Logic . ·
3.5.9
Write/Erase Logic
3.5.10
Read Logic • • • • •
DATA ENCODING AND RECOVERY •
3.6.1· FM Encoding
3.6.2 MFM Encoding •
3.6.3
3.6.4 Data Recovery
3.6.4.1 Bit Shift •••
3.6.4.2 Write Precompensation
3.6.4.3 Data Separation •
3.6.5
Track Format • • • •
·
· .
· .
iv
. .
.
·
. . ·
. . ·
· .
·
·
.
Page
3-12
3-12
3-12
3-12
3-12
3-15
3-15
3-15
3-16
3-16
3-19
3-19
3-19
3-20
3-20
3-23
3-23
3-23
3-24
3-24
3-25
3-25
3-25
3-25
3-26

TABLE OF CONTENTS (Continued)
SECTION 4 MAINTENANCE
4.1
4.2
4.3
4.4
4.5
INTRODUCTION.
GENERAL INFORMATION
PREVENTIVE MAINTENANCE .
4.3.1
Read/Write Head(s) and Load Pad Inspection •
RECOMMENDED TOOLS AND TEST EQUIPMENT •
Removal/Replacement
4.4.1
4.4.2 Adjustment and Measurement .
REMOVAL/REPLACEMENT PROCEDURES .
4.5.1 Printed Circuit Board Assembly (PCBA)
4.5.2 Shield Assembly
4.5.3 Right-Hand Guide/Write Protect Assembly
4.5.4 Left-Hand Guide Assembly •••
4.5.5 Front Panel Bezel and Activity LED.
4.5.6 Cone Assembly
4.5.7 Carrier Assembly.
4.5.7.1 Index LED •••
4.5.7.2 Carrier/Index LED Installation
4.5.8 Index/Load Boss
4.5.9 Solenoid •.
4.5.10 Drive Motor
4.5.11 Track 00 Sensor
4.5.12 Door Button Assembly.
4.5.13 Stepper Band.
4.5.14 Stepper Motor
4.5.15 Head/Carriage Assembly •.
v
. .
· ·
· · · ·
· ·
. · · ·
· · · ·
. .
• .
Page
4-1
4 1
4-2
4-2
4-3
4-3
4-3
4-3
4-10
4-10
4-10
4-11
4-11
4-13
4-13
4-14
4-14
4-14
4-15
4-16
4-17
4-17
4-19
4-20
4-20

TABLE OF CONTENTS (Continued)
SECTION 4 (Continued)
4.5.16 Ejector Assembly
4.5.17 Spindle Bearings
4.5.18 Head Load Pad Assembly .
4.5.19 Harness Assembly •
4.6 ADJUSTMENT PROCEDURES
4.7
4.6.1 Radial-Track Alignment .
4.6.2 Index-To-Data Alignment
4.6.3 Track 00 Sensor Alignment
4.6.4 Speed Control Adjustment .
4.6.5 Track 00 End Stop Adjustment .
4.6.6 Drive Belt Adjustment
4.6.6.1 Mylar (Yellow) Drive Belt Adjustment
4.6.6.2
Neoprene (Black) Drive Belt Adjustment
4.6.7 Ejector Latch and Ejector Latch Release Adjustments
4.6.7.1
Ejector Latch Adjustment
4.6.7.2 Ejector Latch Release Adjustment
MEASUREMENT PROCEDURES . .
4.7.1
4.7.2
Compliance Measurement .
Erase Measurement
4.7.3 High Frequency Playback Measurement
SECTION 5 TROUBLESHOOTING
5.1
5.2
5.3
INTRODUCTION ••.
PRELIMINARY TROUBLESHOOTING STEPS
DRIVE WON'T STEP OR STEPS ERRATICALLY.
vi
. . . .
Page
4-21
4
22
4-23
4-23
4-26
4-26
4-26
4-29
4-29
4-29
4-30
4-30
4-30
4-30
4-32
4-32
4-32
4-32
4-33
4-33
5-1
5-2
5-2

I •
I ~
[
TABLE OF CONTENTS (Continued)
SECT! ON 5 (Continued) , \
5.4
HEAD/CARRIAGE OSCILLATES AT TRACK 00 • • ••
5.5 DRIVE MOTOR WON'T ROTATE. • ••••••••
5.6 HEAD WILL NOT LOAD • • •••
5.7
5.B
5.9
5.10
5.11
5.12
BAD INDEX OUTPUT •
BAD WRITE PROTECT OUTPUT •
ACTIVITY INDICATOR DOES NOT LIGHT
READ ERRORS - ALL TRACKS • •
READ ERRORS - RANDOM TRACKS
READ ERRORS - INSIDE TRACKS
5.13 CANNOT READ PREWRITTEN DATA:
CAN READ SELFWRITTEN DATA
CANNOT WRITE DATA
ERASE BAD •• • •
.. .... . .
. . . ..
5.14
5.15
5.16
DRIVE SPEED UNSTABLE • . . . . . . . . . .. .. .. .
SECTION 6 OPTIONS
6.1
6.2
6.3
6.4
INTRODUCTION
DOOR CLOSED SWITCH •
DOOR LOCK MECHANISM
READY OPTION • • • •
APPENDIX A
APPENDIX B
APPENDIX C
Spare
Parts List
Drawings and Schematics
Signal
Name Definitions
... . .... .
...
vii
Page
5-3
5 3
5-3
5-3
5-4
5-4
5-4
5-4
5-5
5-5
5-5
5-5
5-5
6-1
6-1
6-1
6-2
A-I
B-1
C-1

FIGURE
1-1
2-1
2-2
3-1
3-2
3-3
3-4
3-5
3-6
3-7
3-8
3-9
3-10
3-11
3-12
3-13
3-14
3-15
3-16
3-17
3-18
3-19
3-20
3-21
LIST OF ILLUSTRATIONS
Model 91/92 and 915/925 Disk Drives
Outline and Mounting Dimensions
Diskette Orientation •
Track Access Timing
Read Initiate Timing •
Read Signal Timing • •
Write Initiate Timing
Write Data Timing
General
Control and Data Timing Requirements (head
load solenoid is activated with drive select)
Index/Sector Timing (Soft Sector)
Index/Sector Timing (Hard Sector)
DC Power Connector, J2 • •
Jl Connector Dimensions
Interface Signals
Shunt Configuration
Write Protect Feature
Functional Block Diagram •
Basic Recording Technique
Wave Forms in Read Sequence
Stepper Motor Control Timing
Motor
Control Timing •
Write Timing •
Read Timing
FM Encoding
viii
Page
1-2
. . . 2-3
2-6
3-4
3-4
3-4
3-5
3-5
3-5
3-6
3-6
3-7
3-7
3-8
. .
3-8
3-9
3-11
3-14
3-14
3-17
3-18
... 3-21
3-22
3-24

r
\
f :
\ .
I ,
l,
L
L
L
L
FIGURE
3-22
3-23
3-24
4-1
4-2
4-3
4-4
4-5
4-6
4-7
4-8
4-9
LIST OF ILLUSTRATIONS (Continued)
MFM Encoding • •
M2FM Encoding
Typical Track Format •
Top View Of Drive
Bottom
View Of Drive 0
Model 91S, Exploded View
Activity Indicator Assembly
Door Button Assembly
Stepper Band • 0 •
. ... . .
0
0 •
· . . .. . .
.
.
Ejector Assembly • . . ....
Radial Track Alignment Patterns
Index-to-Data Alignment Pattern
4-10 Ejector Block and Latch - top view •
4-11
Ejector Assembly •
6-1
Door Closed Switch •
• . .
,0
· 0 ·
. . • · · 0 ·
·. ..
0 0 0 ·
· · . 0
0 • 0 •
0 0
'0
B-1
Logic PCBA Component Layout · . .
.. . . . . .. . . . . . . . .
Page
3-24
3-25
3-27
4-5
4-7
4-9
4-12
4-18
4-18
4-22
4-27
4-28
4-31
4-31
6-2
B-2
B-2 Logic PCBA Schematic • 0 • 0 • • • 0 0 • 0 0 0 • • • 0 0 • 0 • • B-3
B-2A
Logic PCBA Schematic B-4
B-3
Ready PCBA Component Layout · . .. . . . . . . . . . . .
.. . . B-5
B-4
Ready PCBA Schematic .. . . . .. . .. .... . . . . . . . .
B-6
ix

TABLE
2-1
3-1
3-2
3-3
4-1
4-2
4-3
4-4
4-5
5-1
LIST OF TABLES
Recommended Connectors -PI
Section Index
Write/Read and
Side Selection Conditions •
Comparison
of Encoding Techniques.
Section Index
Removal/Replacement
Procedures •
Removal/Replacement Adjustment Check List
Harness Assembly Wire List •
Adjustment Procedures
Trouble Symptoms • • •
x
Page
2-2
3-1
3-19
3-27
4-1
4-4
4-8
4-25
4-26
5-1

SECTION 1
GENERAL DESCRIPTION
1.1 INTRODUCTION
This product manual contains specifications and information relating
to the Micro Peripherals Inc. Model 91/92 and 91S/92S Flexible Disk Drives.
This document consists of the following sections:
SECTION
I General Description
SECTION
II Installation -Checkout
SECTION
III Theory of Operation
SECTION
IV Maintenance
SECTION
V Troubleshooting
SECTION
VI Options
APPENDIX
A
Spare Parts
List
APPENDIX
B Drawings and Schematics
APPENDIX
C Signal Name Definition
This section provides a physical and functional description, and
specifications for the Models 91/92 and 91 S/92S Flexible Disk Drives. In
addition to the standard features described, the following additional features
are included in all models:
A. "Write Protect" can be used as "Disk Installed" indication.
B. Termination of input signals can be either 150 ohms or split
220/330 ohms.
1-1

NOTE
A high level of commonality exists between the 91/92 and
915/925 drives. Therefore the following descriptions will
generally apply to all models. Unique features of each
model will be identified and individually described,
as appropriate. For ease of explanation, flexible disk
dr i ves discussed in this product manual will be referred
to as Model 91/92 unless di fferentiation is necessary.
MODEL 915/925
MODEL 91/92
Figure 1-1: 91 / 92 and 915/925 Disk Drives
1-2

1.2 PURPOSE OF EQUIPMENT
The Model 91/92 Disk Drive is a compact disk memory device designed
for random-access data storage, data entry, and data output appl ications.
Typical applications are intelligent terminal controllers, microcomputers,
word processing systems, data communications systems, error logging,
micro-program logging, and point-of-sale terminals. The Model 91/92 is
designed to meet and perform to ANSI specification, utilizing standard
5 1/4 inch diskettes.
1.3 PHYSICAL DESCRIPTION
The Model 91/92 can be mounted vertically or horizonally. However,
when mounted horizonally, it is recommended that the 91/92 be positioned
so that the PCBA is on the top side. The mechanical components consist of
an aluminum chassis, on which is mounted a spindle (belt-driven by a DC
motor); a stepper motor/band combination for positioning the magnetic head
assembly; and a cone/clutch assembly for centering and holding the recording
media under operation. Access for diskette loading is at the front of
the drive.
The recording-head assembly is of a glass bonded ferrite/ceramic
structure, with lifetime expectancy in excess of 20,000 hours. The electronic
circuitry is mounted on a PCBA located on top of the drive. Power and inter-
face signals plug directly into this board. The following basic circuits
are included:
A. Stepper motor control logic
B. Read circuit
C. Write erase circuit
D. Spindle Drive Motor speed control
E. Index; Track 00 and Write Protect sensing
F. Head load drive
1.4 FUNCTIONAL DESCRIPTION
The Model 91 / 92 is self-contained and requires no operator inter-
vention during operation. The drive consists of a media-rotating system, a
head-load and positioning system, and a write/erase and read system. When the
front door is opened, access for inserting the diskette is provided. When
inserting the diskette, all positions except "in/out" are controlled inter-
nally by physical guides. Correct "in/out" is assured by inserting the
diskette until a "click" is heard. On the Model 915/925 all positions except
"out" are controlled by physical guides. A correct "in" is assured by
inserting the diskette until contacting a guide stop.
1-3

Closing the front door activates the cone/clutch system which serves
two purposes in the following order:
A. Correct centering of the media
B. Clamping the media to the spindle hub
The spindle hub rotates at a constant speed of 300 RPM by means of a
DC motor/tachometer and a reference in a closed-loop system. When in opera-
tion, it is important that the head-to-media relationship be controlled.
This is accompl is hed by the h ea d -l oad system in the follow i ng way: Th e media
is pressed aga in st the Index/Load Bo ss wh ich is ref erenc ed t o the h ea d a nd the
spindle hub; and in Mo del 91 /9 15 a felt pad i s l oaded ag ai nst t he media on
the opposite side of the head with a force of approximately 18 gr.
The recording head is positioned over the correct track by means of a
four-phase stepper motor/band direct-drive mechanism, and its associated
electronics. A one-step movement causes a one-track movement. With band
positioning, very high step rates can be accomplished with the 91/92 system.
When a Write Protected diskette is inserted, the write protect sensor
normally d isab les the write/ erase circuits in the drive. When writing,
a 0.00525 i nch (nominal) data trac k is recorded, followed by a tunnel erase
which trims the track down to 0.005 inch (nominal). Data recovery electronics
include a low-frequency amplifier, a differentiator, a cross-over detector, a
digital filter, and a final pulse generator.
1.5 SPECIFICATIONS
The mechanical and electrical specifications for the Model 91/92
Flexible Disk Drives are given in the following paragraphs.
1.5.1 Capacity Specifications (K BYTES)
Single Density (unformatted)
Per Disk
Per Track
Double
Density (unformatted)
Per Disk
Per Track
1.5.2 Functional Specifications
Tracks
Track Density (TPI)
Recording Density (BPI)
Single Density
Double Density
1-4
MODEL 91
250
3.13
500
6.25
80
96
2788
5576
92
500
3.13
1000
6.25
160
96
2961
5922

1.5.2 Functional Specifications (cont'd)
Rotational Speed (RPM)
Average Latency
Transfer Rate
Single Density
Double Density
Encoding Method
Access
Time
Track to Track
Average
Head Settlinq Time
Head Load Time
Power-Up-Delay
Interfacing
1.5.3 Physical Specifications
Environmental
Operating Temperature
Non-Operating Temperature
Operating Humidity
Non-Operating Humidity
Operating Altitude
Non-Operating Altitude
Vibration & Shock (operating)
Electrical
DC Power
Power
Dissipation
Mechanical
Height
Width
Length
Weight
Media Requirements
Diskette
Sectoring
Type
1.5.4 Reliability Specifications
MTBF
MTTR
Design Life
Media Li fe
Data Integrity
Soft Errors
Hard Errors
Seek Errors
UL and CSA Approved
1-5
300 :1 1 /2?~
100ms
125K bits/sec
250K bits/sec
FM,MFM,M2FM
5ms
150ms
25ms
35ms
0.5sec
Industry/ANSI compatible
40°F to 115°F (4.4°C to 46.1°C)
_40°F
to 160°F (-40°C to 71°C)
20% to 80% (non-condensinq)
5% to 95% (non-condensing)
-500 to 10,000 FT(-152.4 to 3,048m)
-1000
to 50,000 FT(-304.8 to 15,240m)
0.5g, 6 to 600Hz
+12V :5%,0.7 Amp (1.4 Amp surge)
O.2v ripple
+5V :5%,0.4 Amp, 0.1v ripple
11W operation; 4W stanrlby
3.25 in.(B2.6mm)
5.75 in.(146.1mm)
7.75 in.(196.9mm)
3.1lbs.(1.41kg)
Industry Compatible, 5 1/4in.
Soft; 10,16
Sinqle or Double Sided
Single or Double Density
9,200 hours (@ 25% duty cycle)
0.5 hours
5 years
3x106 passes/track
1 per 10
9
bits read
1 per 10
12
bits read
1 per 106 seeks

SECTION 2
INSTALLATION AND CHECKOUT
2.1 INTRODUCTION
This section provides the information and procedures necessary to
place the Model 91/92 Flexible Disk Drives into operation.
2.2 UNPACKING
CAUTION
During unpacking, care must be exercised
to ensure that all tools are non-magnetic
and do not inflict damage to the unit.
As the unit is unpacked, inspect it for possible shipping damage. All
claims for this type of damage should be fil ed promptly with the transporter
involved. If a claim is filed for damages, save the original packing mater-
ial. Most packing ma terial may be reuseab le if reasonable care is used in
unpacking. Unpack the drive as follow s :
A. Remove external packing material carefully.
B. Remove the drive from the container.
c. Remove internal packing materials, following instructions provided
on the package.
D. Ensure that front access door opens and closes, and that the
head-load arm raises when door is opened.
E. Ensure that bezel is secured.
F. Ensure that drive hub manually rotates freely.
G. Ensure that stepper motor/head carriage assembly is not binding at
any point, by manually moving carriage back and forth.
2-1

Bottom View
1.87 .125
(4.74cm) 3.125 (.318cm)
,-- .! (7.94cm) I ~
~~~~±I~======~~I~==~~I--~
5.500
(13.97 cm)
~-=-~I =~J-.-=-uJ
'\ I
Door
Open Position
'"
~.
\
r:':::
Door
Closed
Position
(91/92 only
3.38
(8.59 c
)~
i:::
m) L
t
-
-
1.87
tyP~
cm)
. 06
(.15 (4.74 cm)
.31
(.79 cm)
MODEL 91192
6-32 x .31 deep
(4) mtg. holes
...----
PCB
r-r
I
DC Power Connector (J2)
oles (2 pies. each side)
1.1 6-32 thru mtg. h
----1
~-
I> -.875 (2.22 cm)
3.125
~
(7.94 cm)
x 19.3 cm
7.6
ma (
5.87
(14.9
""
1 cm)
....
.L
+
.06 t yp
(.15cm)
.29
(.73 em)
MODEL 918/928
Side View
Figure 2-1: Outline and Mounting Dimensions
(Model 91/92 shown.
All dimensions are
applicable to 915/925 except as noted.)
-
Top View
.-
-
5.75
(14.6
--
1-
!.r -
'/
Single Interface
Connector (J 1)
NOTE: Unless otherwise stated,
dimensions
are in inches.
Tolerances: .xxx
±. 0.010
. xx ±. 0.020
2-3
1 cm)