Sharp FDD-412A User manual

SHARP
_
SERVICE
MANUAL
FLOPPY
DISK
DRIVE
mopeEL
FDD-412A/B
. GENERAL
_
PRINCIPLES
OF
OPERATION
_
MAIN
TENANCE
. TROUBLESHOOTING
. PARTS LIST & GUIDE
SHARP
CORPORATION

FDD412A/B
CONTENTS THIS MANUAL.
This
manual
provides
service
and
all
maintenance
and
service
information
to
support
the
slim,
2-side
double-density
floppy
disk
drive
FDD-412A
and
FDD-412B.
Before
attempting
any
service
or
repairs,
take
time
to
familiarize
yourself
with
this
manual to
make
your
servicing
easier
and
more
efficient.
Currently
this
floppy
disk
drive
use
as
bellow
mentioned
model.
Also
intentionaly
will
be use to other model.
UNIT
NAME
PARTS
CODE
APPLIED
PRODUCT
MODEL
FDD-412A DUNTK3010SCZZ Office computer
HAYAC-2900 SYSTEM
CO2900E
CO02902E
HAYAC-3900 SYSTEM
CO3906E CO3900E
CO3902E CO3903E
CO3904E CO3905E
CO3906E CO3907E
Personal computer
MZ1F05
POS system
OM18FD1
FDD-412B DUNTKS3011SCZZ HAYAC-2900 SYSTEM
CO2900E
Personal computer
MZ1F05
POS system
OM18F D2

GENERAL .........-2 eee
Overview ......eeeeeee
FOaATULES sce cca cee es
PRINCIPLES OF OPERATION
(Oy need 0 | = ee
Configuration: ..c.c6.%
.1 Drive Mechanism ....
.2 Control Electronics
SUSCTTLCALIONS eines
.l1 Performance Specific
.2 Power Requirements .
.3 Mounting Specificati
.4 Environment Specific
.5 Reliability Specific
Recording Media cea
.l Medium Type ........
.2 Handling of Recordin
.3 Recording Methods ..
-4 Data Format ........
Logic Operations .....
.l1 Sensor-Related Opera
-2 Seek Operations ....
.4 Data Write Operation
.5 Data Read Operation
CONTENTS
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.3
Magnetic
Head
Composition
and
Its
Related
Operations
..
ed
ee
FDD412A/B
10
11
11
12
12
13
13
14
15
15
17
19
20
22

FDD412A/B
2.5.6 Operations Related to Spindle Motor Drive Mechanism ...
2.5.7 Overall FDD Operations (Timing Charts) .............:..
Goes
SULCUS
ACE
sxe aca
pea
tae
wae
gel
wetee
ek
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Mawes
So
ok
2.6.1 Connection of Floppy Disk Controller (FDC) to FDD .....
2.6.2
Device
Configuration
in
Daisy
Chain
Connection
........
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26.4 Interface ‘Signal: ‘Timing: 25 ts. wei aiianis wed ob ob cw ieoeelees
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3.1.1 Floppy Disk Not. in USE ose. ee ck es eee dee cee ee oe ean
3,14.2 Insertion of BLoppy: Disk ~ wesc S08 eres ob ese e eS SER! pass
3.1.3 Opening/Closing of Door; Floppy Disk in Use ...........
3.124 Removal’ of Floppy (Disk ..c.ccuiewio Ss Se Moe oes aie, aecateees
3.1.5 Handling of Floppy Disk ..... feet e eee ee eee Stee e eee eee
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3.1.7 Packaging, Transit and Storage ...... eee ee ee ee ees
$72. “Setting of FORD Operation Mode... a qcted easton see es i rates
3.2.1
Operation
Mode
Changed
by
Shorting-Plugs
Seana
careers
lables
eae
s
3.2.2 Shorting-plug Presetting Position oe Shipment
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4.1] Maintenance Items ...... Be thle lets Meinatccen es eae ee
a.2 .Parts Replacement Procedures. is.siaswashae sven yenauwe ers
4.2.1 Common Work 1: Top Cover ...... ee ee
A. 2.2: Common; Work: 22 Pilate Opening/Closinge sss. denc-ee esas
4.2.3 eae Work 3: Wire Handling and Wire Routing ........
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Page
28
29
82
82
33
84
85
45
45
45
45
45
46
46
48
49
49
49
53
54
54
55
55
55
56
58

oO
. 10
il
sed
13
14
jab
. 16
17
18
.19
Motor (DD Spindle) .......
Head Load Solenoid .......
Head
Load
Bail
Assembly
...........--
ion
d
sae
wa,
ayectn
toes
Sua
arate
ely
O
Sensor
Assembly
LL...
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Protect
Sensor
Assembly
...
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eres
Index Sensor Assembly ....
Index LED Assembly .......
MiCroOSWIECH.. i. cd dsvcdeers ee
Center Cone Assembly ....
Plate Assembly ..........-.
Indicator Assembly .......
Door Lock Assembly .......
DOGY’ -BUETON: 63s cbreOee ae eats
FPH-H680T Assembly .......
Setp Motor ..ceeeeeseeeees
Adjustment
Procedures
......
TROUBLESHOOTING
.....--------
Troubleshooting
Flowchart
..
Media-Related Troubles .....
.
ho
Troubleshooting Procedure
Pr ee ee
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.1
Head
Position
(Tracking)
Adjustment
.......-e
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.2
0
Track
Sensor
Position
Adjustment
......-...-e-eeeeeee
.3
Bail
Stopper
Elevation
Adjustment
.......---eeeeeeeeeee
Pe ee
ee
er
Pe
Pictures
of
Normal/Abnormal
Readout
Waveshapes
........
Major Floppy Disk Failures
Pe a ee ee
FDD412A/B
60
61
62
62
63
64
64
65
66
67
67
68
70
71
71
74
75
77
77
85
85
85
85
93

FDD412A/B
for) a for) fo) for) for) for) jor) on > eo iw)
a
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Medi
um
Management.
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weet
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eit
oe
1 Necessity of Medium Management
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ents
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eb
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oe
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CONTROL.
BOARD:
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th
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Control
Board
Schematic
Drawings
—
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Schematic
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Board
Schematic
Drawings
—
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Board
Schematic
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FDD412
A/B
Operating
mode
Setup
Method
vrvcrcrc
cece
Parte
Layout
Chart
45
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daeeevanudes
101
102
108
104
105
107

bel
FDD412A/B
GENERAL
Overview
The FDD-412A/B floppy disk drive (FDD) is a slim, energy-saving,
lightweight FDD that accommodates 2-sided, double-density floppy disks,
based on the technologies implemented in the widely used FDD-101A/201/
401/102D/402D/403D FDD..
The FDD-412A (Model A) incorporates a VFO, while the FDD-412B (Model B)
has no VFO. The user can select either depending on whether there is a
controller VFO or not.
The standard specifications of the FDD are as follows:
Mae
(1)
(2)
(3)
(4)
(5)
(6)
File protection : Transparent
Top cover color .: . Black
Door lock : Electromagnetic door lock mechanism
Features
Slim lined
The body is only half as wide as conventional types. This makes
it possible to install 2 units in a space for a single conven-
tional type.
Lightweight
The FDD weights 3.5 kg or less.
This weight is about 70% of that of our existing models, making
handling procedures much easier.
Field-proven brushless direct drive system
Our field-proven brushless direct drive system is implemented in
a narrower enclosure.
This system is much more reliable than the belt system or brush-
based direct drive system. Without any parts to be replaced
periodically, the system is of a complete maintenance-free design.
‘There is no need to distinguish 50Hz and 60Hz in frequency.
Convenient VFO connecting interface
Up
to
4
FDDs
can
be
connected
to
the
controller.
If
a
system
con-
figuration
includes
one
model
A
FDD,
all
FDDs
can
be
connected
to
the
VFO interface
regardless
of
the
other
three
being
of
model
A
or
B.
This
promises
configurations
of
high
cost-performance.
2-DC power supply
A 2-DC power supply system has replaced the 3-DC power supply
system. This has reduced the average power consumption to about
57% of that of our existing models.
LSI-based circuitry
Dedicated LSIs constitute the greater part of circuitry. Without
any parts to be replaced periodically, higher reliability and much
better maintenability can be realized. .

FDD412A/B
(7) Electromagnetic door lock/umlock mechanism
The
controller
is
equipped
with
an
electromagnetic
door
lock/unlock
mechanism
that
prevents
an
inadvertent
opening
of
the
door
during
operation.
pene
Fig. 1.1 Outside View of FDD-412A/B Floppy Disk Drive
2. PRINCIPLES OF OPERATION
2.1 Outline
The FDD (floppy disk drive) is a device that writes and reads data to
and from the floppy disk.
As shown in Fig. 2.1, a floppy disk has 77 concentric "tracks" on either
surface (i-e., 154 tracks on both sides). Data is sequentially recorded
on each track. A carriage has.one magnetic head on each side respec-
tively, and read/write data. It moves radially, processing data on the
tracks.
To write or read data to or from a given location on the floppy disk,
the following steps are required:
(1) The magnetic head and recording medium are given a relative
velocity.
(2) The magnetic head is positioned over the target track.
(3) The target data is searched from among numerious data records
written on that track. :
(4) The data is read from or written onto the record.

FDD412A/B
.hese
operations
and
their
control
are
shared
by
the
FDD
and
FDC
(floppy
disk
controller).
Each
of
the
above
steps
is
further
explained
below.
(1)
(2)
(3)
Floppy disk
Track
Magnetic head
Fig. 2.1 Floppy Disk
The
magnetic
head
and
recording
medium
are
given
a
relative
velocity.
Data
is
sequentially
recorded
(i.e.,
in
bit-series)
on
floppy
disk.
For
data
processing,
it
then
becomes
necessary
to
move
the
mag-
netic
head
relative
to
the
medium.
This
is
achieved
by
rotating
the
floppy
disk.
The
motion
is
provided
by
an
FDD
spindle
motor,
which
rotates
at
a
constant
speed
for
correct
reading.
Applying
power
to
the
FDD
rotates
the
spindle
motor.
With
a
floppy
disk
inserted
and
the
door
closed,
the
disk
is
secured
to
the
spindle,
ready
for
revolutions.
The
magnetic
heads
are
fixed
to
the
FDD.
As
the
floppy
disk
rotates,
a
relative
velocity
is
pro-
duced
between
the
heads
and
the
disk.
The
floppy
disk
has
an
index
hole
to
determine
the
start
point
on
each
track.
The
FDD
senses
the
index
hole.
When
the
disk
rota-
tion
is
found
normal,
the
FDD
enters
a
ready
state
and
can
be
subject
to
control
from
the
FDC.
The
magnetic
head
is
positioned
on
the
target
track.
The
magnetic
head
is
then
positioned
on
the
target
track
among
many
concentric
tracks.
The
positioning
is
done
by
moving
the
head
radially.
How
far
the
head
should
move
is
calculated
by
the
FDC
as
the
positional
difference
between
the
current
track
and
the
target
track.
The
FDD
receive
pulses
indicating
the
amount
of
magnetic
head
relocation.
The
FDD
has
a
step
motor
to
which
the
magnetic
heads
are
secured.
One
pulse
causes
the
head
to
move
by
1
track.
In
this
manner,
the
head
is
positioned
on
the
target
track.
The target record is’ searched.
When positioned on the target track, the head reads out data from
the track.
To minimize wear, the FDD is designed so that the head comes in
contact with the disk surface only upon reading/writing. The FDC
issues a HEAD ENGAGE command to the FDD for contact between the-
head
and
the
disk.
:

FDD412A/B
(4)
Ze
The
The
FDD
reads
out
the
data
from
disk
and
sends
it
to
the
FDC.
The
FDC
searches
the
target
record
as
it
reads
data
on
the
track.
One
record
consists
of
an
ID
part
(identifier)
and
a
data
part.
Reading
the
ID
part
reveals
whether
or
not
the
record
is
what
is
needed.
Index : Index
VY V
IDO ! Data 0 | ID1 ! Data 1 | ID2 : Data 2
{ :
EL RCCOEE Soe
IDn ! Data n
Fig. 2.2 Data Arrangement on Track
The data is read out or written in.
When the target record is found, data is written to or read from
the data part.
The magnetic heads of the FDD are used for both heading and writ-
ing. When a write command is given by the FDC, a current flows in
the magnetic head and all readout operations are suppressed.
That is, the FDD performs either a write or readout operation at
any one time, not both simultaneously. The data read from disk is
of analog waveshapes, which are digitized by the FDD for trans-
mission to the FDC.
The model A FDD incorporates a VFO circuit, and is capable of
demodulating the data that was modulated by the so-called FM/MFM
magnetic recording method.
Configuration
FDD is composed of a drive mechanism and the control electronics,
as shown in Fig. 2.3 (on page 14).
Zerdee
The
reo)
(2)
(3)
1 Drive Mechanism
drive mechanism consists of the following:
Carriage
The carriage is equipped with 2 magnetic heads for side 0 and side
1.
For movement, the carriage receives step motor revolutions via a
steel belt.
Step motor
The step motor turns in response to the STEP-N signal from the
controller.
Step motor revolutions are transmitted via the steel belt to the
carriage which positions the magnetic head at a given location.
Spindle motor
The floppy disk medium is press-fit to the spindle motor by a
collet for rotation.

on
Lf
Ne
(5)
(6)
(7)
(8)
(9)
(10)
FDD412A/B
The rotational speed of the spindle motor is 360 rpm.
Head load solenoid
By sensing the presence and absence of the HEAD ENGAGE-N signal
from the controller, the head load solenoid engages the magnetic
head (to enable reading/writing) and disengages it (to disable
reading/writing).
Index sensor
Two pairs of LEDs and phototransistors are installed to tell
whether the recording medium is l-sided or 2-sided.
The distinction is accomplished by detecting an index hole on the
medium for index pulse generation.
QO track sensor
With respect to the carriage position, the O track sensor detects
the magnetic head at track.0 position and causes the TRACKOO-N
signal to be generated.
Auto-ejector mechanism
The auto-ejector mechanism consists of a spring-and-latch arrange-
ment capable of the following functions:
(a) Upon insertion of floppy disk
The floppy disk, upon insertion, is not latched and is rejected
until it is in place.
This function accurately positions the floppy disk center
hole to the spindle, protecting the hole from damage and
preventing track dislocation.
(b) Upon disk removal
Opening the door allows part of the floppy disk to pop out of
the FDD.
File protection
The file protection mechanism comprises a pair of LED and photo-
transistor, and a logic circuit. It checks if the floppy disk
jacket has an inhibit notch. If the notch is found to be present,
data write operation is inhibited.
Spindle motor controller
The spindle motor controller is an electronic control circuit that
keeps the brushless direct drive motor turning at a constant speed
by accommodating load changes.
Electromagnetic door lock mechanism
In this mechanism, an electromagnetic door lock solenoid is driven
by a control signal from the FDC to lock/unlock the door.
2.2.2 Control Electronics
(1)
The control electronics consists of control logic circuitry com-_
prising read/write control circuits, and controls the FDD accord-
ing to instructions from the FDC. With model A, the VFO circuit
is part of the control electronics.

FDD412A/B
(2) The VFO circuit modifies in timing the signals read out from the
floppy disk, divides them into clock and data signals, and trans-~
mits them to the FDC. ;
Door lock solenoid
Door switch
SS Indicator LED
PS
~t
Index
1
Floppy disk |
t
; sensor
[ S | (Photo-
ae DD ;/{ transis-
tors)
\ ea
Spindle
Collet motor
{Index sensor
(LEDs)
|
Carriage
Step motor
File
protect
sensor
Head load
solenoid
0 track
sensor
Spindle motor | VFO Control electronics
control circuit circuit (Read/write control circuits)
Fig. 2.3 Device Composition

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FDD412A/B
2.3 Specifications
2.3.1 Performance Specifications
Table 2.1 Performance Specifications
Performance
Single-sided Two-sided Two-sided
Single Density|Single Density |Double Density
Storage
capacity
KB
Sector
format
Data transfer rate
K bits/sec
Recording density B
a
ee
Number
of
cylinders
me
7d
Number of tracks 77 154
pacodiae medio’ FM
Disk
rotational
speed
rpm
360
Mean
latency
ms
83
Access time
Track to track
Average (excluding
setting)
Head loading time
Starting time

22 332
FDD412A/B
Power Requirements
Table 2.2 Power Requirements
Number of
configured units
Model type
Current
consump-
tion
Power
consump-
tion ©
Note 1:
Note 2:
Note 3:
DC+24V
L
DC+5V
L
a |
1A
+10%
—
3.9A | 3.3A | 5.24
+5%
3.1A |2.7A | 4.14
ee el ee
Avg.
The
current
and
the
power
consumption
data
include
the
period
from
power
application,
to
the
time
the
spindle
motor
has
reached
a
normal
speed.
The
average
current
and
power
consumption
data
are
for
refer-
ence,
based
on
the
mean
voltage
and
average
environment.
The
conditions
under
which
the
data
were
collected
are
as
follows:
IBM's
or
Hitachi
Maxell'’s
medium
is
mounted
on
the
FDD.
-
All
FDDs
connected
to
the
FDC
are
powered
on.
The
FDC
is
performing
a
seek
operation
on
one
FDD
with
its
head loading on the medium.
The
power
voltage
is
regulated
on
the
FDD
side.

FDD412A/B
2.3.3 Mounting Specifications
Table 2.3 Mounting Specifications
Specification
Outside dimensions
57(W) X 217(H) * 330(D) (Note 1)
Vibrations
3.5 max.
Under operation
0.25 (5 % 20Hz)
Under Vibration
non-operation
Peak value of allowable DC line
input noise (rise/fall time:
500 ns min.)
Mounting direction
5 (5 ~ 20Hz)
20 (Rise time : 10 ms min.
Pulse width: 20 ms max.)
Note 1: The outside dimensions exclude a handle protrusion of 10 mm.

FDD412A/B
2.3.4 Environment Specifications
Table 2.4 Environment Specifications
Item
Specification
Ambient temperature °C See Note l.
Under operation
Under non-operation
[vader transit
Relative humidity
Under operation
Under non-operation
Under transit
Wet bulb temperature °C 29 max., without dew condensation
Note 1: The temperature gradient must be 10°C/Hr or less.
2.3.5 Reliability Specifications
Table 2.5 Reliability Specifications
Specification
10000
MTBF (under operation) (Hr)
0.5
5 years or 15,000 POH
(whichever is shorter)
Error rates
Recovery times/bit
Non-
recovery
times/bit
Seek times/bit
Medium life pass/track
Bone eee IBM DISKETTE I, Il, IID; or
tas ar laa: HITACHI MAXELL FD1, FD2, FD2-D
-~i1-

FDD412A/B
2.4 Recording Media
2.4.1 Medium Type
(1)
As
shown
in
Fig.
2.5,
the
recording
media
for
the
FDD
is
floppy
disk:
composed
of
flexible,
oxide-coated
mylar
sheet
housed in a dedicated jacket. .
Except for the index hole position, both the single-sided and
two-sided floppy disks are of the same shape.
(2) IBM's floppy disks (IBM DISKETTE I, II, IID) are the standard
recording media.
(3) To use the file protection feature requires an inhibit notch, the
specifications of which are shown in Fig. 2.5.
Index hole (two-
sided floppy disk)
Index hole (single-
sided floppy disk)
\
I | -
i | Be
\ / <
\ / ie
“N
ead contact hole
| | 33,
| 4 4033/7
Fig. 2.5 Recording Medium
~12~—

FDD412A/B
2.4.2
Handling
of
Recording
Media
Giv
(1)
(2)
(3)
(4)
(5)
(6)
The
(1)
(2)
(3)
en
below
are
general
cautions
for
handling
the
recording
media:
Do
not
pierce
the
medium
jacket
with
a
pin,
put
a
clip
on
it,
or
write
directly
on
it
in
pencil.
Store
recording
media
in
a
dust-free
place.
They
should
always
be
housed
in
their
respective
cases
and
placed
horizontally
or
vertically.
In
horizontal
storage,
do
not
stack
the
disks
more
than
five
high
so
as
to
prevent
deformation.
The
recording
medium
should
be
under
the
following
ambient
condi-
tions
for
at
least
5
minutes
before
use:
Temperature
:
10%
43°C
Relative
humidity
-
:
20
%
80%
Maximum
wet
bulb
temperature
:
29°C,
without
dew-condensation
Do
not
touch
or
wipe
with
solvent
the
oxide-coated
medium
surfaces.
Keep
recording
media
away
from
magnetic
fields.
Do
not
expose
recording
media
to
heat
or
directly
to
the
sun.
.3 Recording Methods
FDD
utilizes
two
recording
methods:
FM
and
MFM.
FM
(frequency
modulation)
method
Flux
change
does
not
occur
at
data
'0'
but
takes
place
at
data
‘1'.
Clock
bits
are
inserted
between
data
items
to
indicate
the
range
of
data
presence
(bit
cell).
MFM
(modified
frequency
modulation)
method
Flux
change
does
not
occur
at
data
'0'
but
takes
place
at
data
'1'.
Clock
bits
are
inserted
only
where
O's
are
continuous.
MEM
me
thod
as
ee
ae
VN
es
mesitateses-
|
[a
bal
ad
ed Ee
(WINDOW)
Extracted
data
Fig. 2.6 MF Method and MFM Method
Comparison of FM method with MFM method
Table 2.6 A Comparison of FM Method with MFM Method
~13—

FDD412A/B
Recording : Data Transfer Pulse Frequency
Method Bee Rate Interval
(KB/s) (us) (kHz)
Frequency Ratio
2.4.4 Data Format
While the floppy disk needs to be initialized in advance to the pre-
determined format, the data format must meet the following requirements.
IBM—based data formats will meet all of them.
(1) Length of ID part § 224 us
(2) Length of gap across ID part to data part (exclusive of VFO area)
2 512 us.
(3) Length of gap across data part to ID part (exclusive of VFO area)
2 544 us.
(4) The VFO area should be of 6 bytes or more for the FM method and
12 bytes or more for the MFM method, with the (00)ig pattern.
(5) The gap pattern should be (FF),g for the FM method and (4E)j, for
the MFM method.
(6) The gap following the CRC to be updated upon writing to the data
part should be of 1 byte or less.
(7) Writing solely onto the ID part (partial write) should not be
- done.
As an example of double density recording onto the floppy disk,
Fig. 2.7 shows an IBM format and Table 2.7 fives the contents of the
format.
INDEX INDEX
1 !
~ 1 track _
Special |
i
ID eee | record—_——+]
vy | | I :
c5[cifAle2[ 1 |o3f vata |csf mw |e3f vata |esjcr
~
!
Fig. 2.7 IBM Data Format
~14-—