Teac FD-55AV User manual
TEAC
FD-55AV/
GV
MINI FLEXIBLE DISK DRIVE
MAINTENANCE
MANUAL
REV.
A
TEAC
FD-5SAV
~
GV
MINI
=~XI3LE
DISK
DRl~JE
H.~INTI:N;'_~G
P.Jl..NU;lL
- i -
TABLE
OF
CONTENTS
Title
Page
SECTION 3
THEORY
OF
OPERATION
300
3-1
CONSTRUCTION
AND
FUNCTION
301
3-1-1
General
Block
Diagram
301
3-1-2
Mechanical
Section
_
302
3-2
CIRCUIT
DESCRIPTIONS
307
3-2-1
Read
Write
Circuit
307
3-2-1-1
Mode
selector
(for
read
write
circuit)
309
3- 2
-1
- 2
Re
a d c
ire
u
it.
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
..
311
3-2-1-3
Wri
te
circui
t
.....•...........................................
315
3-2-1-4
Low
voltage
sensor
317
3-2-1-5
Function
and
operating
waveform
of
read
write
LSI
terminals
318
3-2-2
Control
Circui
t
326
3-2-2-1
Strap
circui
t
328
3-2-2-2
LED
and
head
load
control
circuit
......•......................
329
3-2-2-3
Write/erase
control
circuit
333
3-2-2-4
Mc>tor
on
gate
...........................................•.....
335
3-2-2-5
Ready
detector
336
3-2-2-6
Stepping
motor
control
circuit
339
3-2-2-7
Track
counter
343
3-2-2-8
Other
terminals
and
function
of
control
LSI
344
3-2-2-9
Interface
driver
346
3-2-3
Servo
Circuit
347
3-3
FUNCTION OF
TEST
POINTS
AND VARIABLE
RESISTORS
3~8
3-3-1
Function
of
Test
Points
349
3-3-2
Function
of
Variable
Resistors
354
-
ii
-
Title
Page
SECTION 4
MAINTENANCE
........................•.........................
4000
4
-1
GENERAL.............
............................................
..
4001
4-1-1
Periodic
Maintenance
4001
4-1~2
Check
and
Adjustment
.'
4002
4-1-3
Maintenance
Jigs
and
Tools
4003
4-2
PRECAUTIONS...............................................
. . . . . .
..
4007
4-2-1
Torque
Applied
to
Screws
and
Locking
Paint
4007
4-2-2
Handling
of
Connectors
4008
4-2-3
Head
Cable
Treatment
4013
4-2-4
Initial
Setting
of
SKA-G
and
SKA
4015
4-2-4-1
Cable
connection
and
setting
of
power
supply
voltage
4015
4-2-4-2
Setting
of
the
maximum
track
number
4018
4-2-4-3
Setting
of
step
rate
and
settling
time
.~
•.....................
4018
4-2-4-4
Level
disk
calibration
4021
4-2-4-5
Alignment
disk
calibration
4023
4-2-4-6
Humidi
ty
setting
4026
4
-2-4
- 7
Setting
0f
SKA
gain
4026
4-2-4-8
Setting
of
FDD
straps
and
SKA
special
key
4027
4-2-5
Others
4029
4-3
PREVENTIVE
MAINTENANCE
4032
4-3-1
Cleaning
of
Magnetic
Head
by
Cleaning
Disk
4032
4-3-2
Direct
Cleaning
<Single
sided}
4034
4-4
CHECK
AND
ADJUSTMENT
4036
4-4-1
Adjustment
of
Set
Arm
Position
4036
4-4-2
Check
and
Adjustment
of
Holder
Position
....•....................
4038
4-4-3
Check
and
Adjustment
of
Arm
Lifter
4041
4-4-3-1
[)()uble
sided
4041
4-4-3-2
Single
sided
4051
4-4
-4
Check
of
CSS
Ass'
Y-.f054
4-4-5
Check
of
File
Protect
Sensor
............•.......................
4058
4-4-6
Check
of
Disk
Rotation
Speed
4061
4-4-7
Check
of
Erase
Gate
Delay
4063
4-4-8
Check
of
Head
Touch
4066
-
iii
-
4-4-9
Title
Check
and
Adjustment
of
Asymmetry
Page
4072
Check
and
Adjustment
of
Track
Alignment
.........................
4084
Check
and
Adjustment
of
Track
00
Sensor
........................
4093
Check
and
Adjustment
of
Track
00
Stopper
.......................
4100
Check
and
Adjustment
of
Index
Burst
Timing
.....................
4105
4077
4080
Check
of
Resolution
Check
of
Read
Level
4-4-10
4-4-11
4-4-12
4-4-13
4-4-14
4-4-15
4-5
MAINTENANCE
PARTS
REPLACEMENT
4110
4-5-1
Replacement
of
Head
Carriage
Ass'y
........................•.....
4110
4-5-1-1
4-5-1-2
Replacement
of
v-type
carriage
Replacement
of
L-type
carriage
4110
4117
4-5-2
Replacement
of
Stepping
MQtor
Ass
'y
4121
4-5-3
Replacement
of
DD
motor
Ass'y
<Spindle
motor},
4124
4-5-4
Replacement
of
Collet
Ass'y
4126
4-5-5
Replacement
of
Head
Load
Solenoid
........•......................
4127
4-5-6
Replacement
of
Track
00
Sensor
Ass'y
4129
4-5-7
Replacement
of
PCBA
MFD
Control
#H
4130
4-5-8
4-5-9
Replacement
of
PCBA
Front
OPT
#H
Replacement
of
Front
Bezel
Ass'y
4132
4133
4-5-10
Replacement
of
Front
Lever
Ass'y
4134
4-5-11
Replacement
of
CSS
Ass'y
4135
4-5-12
Replacement
of
Head
Pad
(Single
sided)
.........•................
4136
-
iv
-
SECTION 3
THEORY
OF
OPERATION
-
300
-
3-1.
CONSTRUCTION
AND
FUNCTION
3-1-1.
General
Block
Diagram
Read
write
circuit
READ
DATA
SIDE
QNE
SeLECT
WRITE
DATA
DRIVE
Sc.:LECT
()'\..3
WRITE
GATE
MOTOR
ON
STEP
DIRECTION
SELECT
IN
USc.:
/
HEAD
LOAD
TRACK
00
INDEX
WRITE
PROTECT
READY
+12V,+SV,OV
Cunt.rol
circuit
Indi-
cator
Servo
circuit
Magnetic
head
Head
load
solenoid
Track
00
sensor
Stepping
motor
File
protect
sensor
sensor
LED
Index
sensor
Index
sensor
LED
Spindle
motor
(Fig.30l)
General
block
diagram
-
301
-
3-1-2.
Mechanical
Section
Since
the
disk
is
a
flexible
recording
media
made
of
mylar
film
base
and
data
interchangeability
between
disks
and
FDDs
is
required,
the
mechanical
section
of
the
FDD
uses
precision
parts
and
it
is
also
assembled
carefully
and
precisely.
For
this
reason,
only
trained
technicians
can
handle
the
internal
mechanism.
Never
apply
excessive
impact
nor
drop
the
FDD
down
on
the
desk.
The
mechanical
section
is
constructed
with
frame,
door
mechanism,
disk
clamp
mechanism,
disk
rotation
mechanism,
magnetic
head
and
carriage,
head
load
mechanism
(or
CSS
mechanism),
head
seek
mechanism,
various
detection
mechanisms,
etc.
(1)
Frame
The
main
structure
for
mounting
the
various
mechanisms
and
printed
circuit
boards.
The
frame
is
made
of
aluminum
diecast
to
maintain
the
stability
of
the
FDD
in
strength,
precision,
durability,
and
expansion
coefficient.
(2)
Door
mechanism
and
disk
clamp
mechanism
The
door
mechanism
is
constructed
with
the
main
parts
of
set
arm
which
forms
the
structure
for
installing
the
disk
on
the
spindle;
other
parts
of
front
lever,
clamp
arm,
etc.
The
set
arm
is
attached
to
the
rear
of
the
frame
with
leaf
spring
and
on
the
tip
of
the
set
arm
a
collet,
which
forms
the
disk
clamp
mechanism,
is
attached.
When a
disk
is
inserted
and
the
door
is
closed,
the
collet
is
inserted
into
the
center
hole
of
the
disk
and
the
disk
is
clamped
in
the
correct
position
along
the
outer
circumference
of
the
collet.
(3)
Disk
rotation
mechanism
The
disk
rotation
mechanism
comprises
DO
motor
Ass'y
which
includes
-
302
-
spindle.
The
DO
motor
is
an
outor-rotor
type
DC
brushless
motor
which
has
the
long
life
of
30,000
hours
or
more
in
continuous
rotation.
The
rotation
speed
is
300rpm
for
A
~
F
models
or
360rpm
for
G
model
and
is
maintained
at
a
stable
condition
against
load
variations
and
environmental
changes.
This
is
achieved
by
a
feedback
signal
from
the
internal
AC
tachometer.
The
collet
and
the
spindle
are
combined
precisely
to
maintain
the
center
position
correctly
without
damaging
the
center
hole
of
a
disk
and
so
as
to
make
the
head
be
in
contact
with
the
disk
at
a
correct
position.
(4)
Magnetic
head
and
carriage
Read/wri
te
core
gaps
___
Rota
tional
direction
of
disk
Erase
cores
(Fig.302)
External
view
of
magnetic
head
core
The
magnetic
head
assembly
(head
carriage
Ass'y)
of
a
single
sided
model
(A
or
E
model)
is
button
type,
which
is
mounted
on
the
carriage
to
be
in
contact
with
the
head
window
area
of
the
side
0
surface
of
a
disk
(down
surface
when
the
FDD
is
situated
horizontally).
For
a
double
sided
model
(B,
F,
or
G
model),
both
of
the
side
1
head
and
the
side
0
head
are
special
flat
type
supported
with
the
gimbaled
mechanisms.
The
two
magnp.tic
heads
are
mounted
accross
the
disk
on
one
carriage
(head
carriage).
In
both
types
of
head,
the
surface
is
designed
for
iltinimWii
disk
wear
and
maximum
read
output.
The
head
itself
is
a
long
life
type
for
improved
head
wear.
Each
head
is
constructed
with
a
read/write
gap
-
303
-
used
for
data
reading
and
data
writing
and
two
erase
gaps
to
erase
the
recorded
track
edge
immediately
after
the
recordinCJ
(tunnel
erase).
The
magnetic
ehad
and
the
carriage
form
the
core
section
of
the
FDD
and
is
specially
assembled
with
high
precision.
(5)
Head
load
mechanism
or
CSS
mechanism
The
head
load
mechanism
is
used
for
models
with
head
load
solenoid
and
the
CSS
mechanism
is
used
for
double
sided
CSS
model
without
head
load
solenoid.
The
head
load
mechanism
functions
to
make
the
head
in
contact
with
a
disk
when
only
required
so
as
to
reduce
disk
and
magnetic
head
wear.
This
mechanism
is
constructed
with
head
load
solenoid,
arm
lifter,
etc.
If
the
head
loading
is
executed
for
a
single
sided
model,
the
head
pad
attached
to
the
pad
arm
of
the
carriage
is
depressed
lightly
against
the
side
1
surface
of
a
disk.
For
a
double
sided
model,
the
side
1
head
attached
to
the
upper
arm
of
the
carriage
is
depressed
against
the
side
1
surface
of
a
disk
with
an
appropriate
pressure.
The
side
0
surfaces
of
the
head
and
the
disk
are
set
to
the
same
height
and
the
depression
of
the
side
1
head
produces
the
stable
contact
between
the
heads
and
the
disk.
In
the
CSS
model,
the
magnetic
heads
are
always
in
contact
with
a
disk
as
far
as
the
disk
is
installed.
In
order
to
elongate
the
disk
and
head
leves,
it
is
required
to
make
the
disk
rotate
only
when
it
is
necessary.
The
CSS
mechanism
is
constructed
with
aCSS
ASs'y
which
is
designed
to
protect
the
contact
of
side
0
and
side
1
heads
directly
when
the
front
lever
is
closed
without
disk.
For
the
purpose
os
protecting
the
head
being
caught
and
damaged
by
the
head
window
edge
during
disk
insertion
and
ejection,
head
protector
is
also
equipped
to
the
CSS
mechanism
to
lift
up
the
disk
jacket.
The
head
protector
is
also
used
-
304
-
in
models
with
head
load
solenoid.
(6)
Head
seek
mechanism
The
head
seek
mechanism
consists
mainly
of
stepping
motor
with
a
capstan
(pooly),
steel
belt
(band),
and
guide
shafts.
The
head
carriage
is
connected
to
the
capstan
of
the
stepping
motor
through
the
steel
belt
and
is
slided
along
the
guide
shafts.
The
stepping
motor
rotates
2
steps
(3.6°)
in
48tpi
models
and
I
step
(1.8°)
in
96tpi
models
for
one
track
space.
In
some
48tpi
models,
the
stepping
motor
rotates
3.6
0
for
one
steps.
For
all
models,
hybrid
type
4-phase
stepping
motor
is
adopted
to
improve
speed
of
the
head
seek
operation
and
precision
of
the
head
positioning.
This
special
motor
is
driven
in
a
unique
manner
which
brought
a
success
in
reducing
the
heat
radiation
and
to
obtain
a
highly
precise
positioning.
The
parallelism
and
the
distance
between
the
shafts
and
the
center
line
of
a
disk,
and
shafts
and
capstan
themselves
are
precisely
machined.
Also
the
thermal
expansion
of
the
frame,
steel
belt,
carriage,
etc.
are
taken
into
consideration
in
the
process
of
design
so
that
they
are
mutually
offset
with
the
expansion
of
the
disk.
(7)
Detection
mechanisms
(a)
File
protect
detection
mechanism
This
mechanism
is
constructed
with
an
LED
and
a
photo-transistor
to
detect
the
existence
of
the
write
enable
notch
of
the
disk
jacket.
When a
disk
with
the
notch
covered
is
installed
and
the
light
pass
for
detection
is
disturbed,
no
write
or
erase
current
will
be
supplied
to
the
read/write
and
erase
heads
and
the
recorded
information
on
the
disk
is
protected
from
an
erroneous
input
of
a
write
command.
The
LED
is
mounted
on
the
PCBA
DD
motor
servo
and
the
photo-transistor
on
the
PCBA
front
OPT
#H.
-
305
-
(b)
Track
00
detection
mechanism
This
mechanism
is
constructed
with
a
photo-interrupter
for
detecting
the'outermost
track
position
(track
00)
of
the
head
and
with
a
track
00
stopper
which
are
attached
to
the
rear
side
of
the
head
carriage.
Inside
tracks
from
the
track
00
on
the
disk
are
used.
Even
if
an
erroneous
step
out
command
is
input
from
the
track
00
position,
the
command
will
be
ignored
by
the
internal
circuit
of
the
FDD.
If
the
head
moves
out
from
the
track
00
by
some
reason
(such
as
impact
during
transportation),
the
head
carriage
strikes
the
track
00
stopper
to
protect
the
head
from
moving
out
of
the
returnable
range
at
a
next
power
on.
If
V-type
carriage
is
used
(refer
to
Note
12
of
item
5-2-1
and
Table
505),
the
frame
edge
functions
like
a
track
00
stopper.
And
if
L-type
carriage
(refer
to
Table
504)
is
used,
a
screwed
small
parts
functions
as
a
track
00
stopper.
When
step-in
commands
are
input
frOIn
the
innermost
track,
the
head
moves
toward
inward
with
an
appropriate
space
left
against
the
head
window
edge
of
the
disk.
In
order
to
recalibrate
the
track
from
this
position
(returning
operation
to
the
track
00),
it
is
required
to
input
the
step-out
commands
with
several
additional
steps
to
the
maximum
track
number.
(c)
Index
detection
mechanism
LED
and
photo-transistor
for
detecting
the
index
hole
are
located
at
the
index
window
area
of
the
disk
jacket.
The
LED
is
mounted
on
the
PCBA
DD
motor
servo
(in
the
rotor
of
spindle
motor)
and
the
photo-transistor
on
the
PCBA
front
OPT
#H.
The
index
hole
will
be
detected
along
the
rotation
of
the
disk.
-
306
-
3-2.
CIRCUIT DESCRIPTIONS
The
electronics
of
the
FDD
is
constructed
with
three
sections
which
are
read
write
circuit,
control
circuit,
and
servo
circuit.
Read
write
circuit
and
control
circuit
are
mounted
on
the
PCBA
MFD
control
#H,
and
servo
circuit
is
on
the
PCBA
DD
motor
servo.
3-2-1.
Read
write
Circuit
The
read
write
circuit
is
constructed
with
mode
selector,
read
circuit,
write
circuit,
low
voltage
sensor.
They
are
mostly
packed
in
a
read
write
LSI
(bipolar
LSI,
U5).
Fig.303
shows
the
block
diagram.
-
307
-
(Fig.303)
Block
diagram
of
read
write
circuit
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DR
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VER
ft
Re.
R9.Q1
~
~,
I
~-----
w
a
CD
3-2-1-1.
Mode
selector
Mode
selector
is
constructed
with
the
switch
filter
and
write
current
switch,
which
are
used
only
for
96tpi
models.
Table
301
shows
the
switching
condition
of
the
read
write
circuit
by
the
track
switch
signal
(SF
signal
in
the
schematic
diagram)
from
the
control
circuit.
(1)
Switch
filter
Switch
filter
is
used
only
in
G
model
and
in
optional
F
model
for
eliminating
the
influence
of
saddle
waveform
(refer
to
Fig.304)
at
the
outer
tracks.
When
the
SF
signal
is
HIGH
level,
the
output
of
the
NPN
transistors,
Q7
and
Q8
(includes
resistors
int~rnally)
becomes
LOW
level.
Then
the
switch
filter
capacitors,
C30
and
C3l
are
activated
to
increase
the
capacity
of
the
low
pass
filter
capacitor,
C29.
This
state
is
the
On-state
of
the
switch
filter,
and
the
cut-off
frequency
of
the
low
pass
filter
is
set
to
low.
(2)
Write
current
switch
Write
current
switch
is
used
only
in
E,
F,
and
G
models
and
used
for
making
the
write
current
in
outer
tracks
(track
00
to
track
43)
higher
than
in
inner
tracks
(track
44
to
track
79)
to
improve
the
over-write
(write
2F
after
IF
write
and
measure
the
residual
frequency
components
of
IF)
and
sholder
characteristics.
Write
current
is
supplied
to
the
write
driver
by
write
current
source
in
the
read
write
LSI,
US.
The
supplied
value
from
this
current
source
can
be
calculated
from
the
following
expression
combining
the
external
resistors
R9,
R8,
and
Ql
(ON
at
outer
tracks)
.
13.2
12.7
12
1
Outer
tracks:
Iw=
~
+
~
-
O.
---
No.
-
309
-
13.2
Inner
tracks:
Iw=
----
-
0.12
---
No.2
R9
(Reference)
Erase
current
is
calculated
from
the
following
expression.
Write
current
is
not
switched
depending
on
the
tr~ck
position.
Ie=
10.8
---
No.3
Rll
(or
R12)
Models
and
track
position
Switching
item
A,B
(48tpi)
E,F
(96tpi)
.
G(96tpi,high
density)
all
tracks
Tr.00'V43
Tr.44'V79
Tr.0Q'V43 Tr.44'\.,79
SF
signal
......
.
.....
H H LHL
Switch
filter
I
No
circuit
ON
OFF
ON
OFF
Write
current
sw.
Constant
No.1
No.2
No.1
No.2
(Current
exp.)
No.2
Erase
driver
Constant
++++
(Current
exp.)
No.3
(Table
301)
Switdhing
function
of
mode
selector
for
read
write
circuit
-
310
-
3-2-1-2.
Read
circuit
The
read
circuit
consists
of
head
matrix
switch,
pre-amplifier,
low
pass
filter,
differentiation
amplifier,
peak
detector,
time
domain
filter,
and
output
driver.
Main
circuits
are
enclosed
in
the
read
write
LSI,
US.
The
minute
voltage
induced
in
read
operation
by
the
read/write
head
i·s
input
to
pre-amplifier
via
matrix
switch
for
selecting
side
0/1
heads.
The
pre-amplifier
has
three
gain
setting
terminals,
GSa,
GSI
and
GSC.
In
A
~
F
models,
GSO-GSC
is
shorted
to
obtain
the
gain
of
100
times,
while
GSl-GSC
is
shorted
in
G
model
to
obtain
the
gain
of
200
times.
The
pre-amp.
output
is
supplied
to
the
differentiation
amplifier
via
\
the
low
pass
filter
and
the
switch
filter
to
~liminate
undesirable
high
frequency
noises.
The
differentiation
amplifier
phase-shifts
the
peak
position
of
the
reproduced
waveform
to
zero
cross
point,
and
at
the
same
time,
further
amplifies
the
signal
with
the
most
appropriate
equalization.
The
peak
detector
constructed
with
a
comparator
converts
the
differentiated
output
after
passing
through
the
coupling
capacitors,
C24
and
C25
into
a
~quare
wave.
The
time
domain
filter
eliminates
a
virtual
pulse
caused
by
the
saddle
in
the
low
frequency
area
(IF
area,
62.5KHz
for
A
~
F
models,
125KHz
for
G
model)
at
outer
tracks.
The
time
domain
filter
is
constructed
with
two
edge
detectors,
delay
single
shot,
read
data
latch,
and
data
single
shot.
Then
the
signal
is
output
from
the
FDD
through
the
RD
driver
and
the
output
driver.
In
the
RD
driver
(3-state
output)
of
the
read
write
LSI,
US,
there
are
some
gates.
To
the
TDCR
terminal
for
pulse
width
setting
of
delay
single
shot
m.v.,
control
signal
from
the
control
circuit
(OPEN/ROYO/
APS
signal)
is
input
in
parallel.
These
control
signals
are
different
depending
on
PCB
issue
numbers
(A
~
0,
E,
or
F
~)
and
PDD
models
(PCBA
versions).
Anyway,
the
FDD
is
so
set
that
the
RD
terminal
outputs
positive
read
pulses
at
read
operation.
Table
302
shows
the
control
function.
-
311
-
PCB
Typical
RD
output
control
No
positive
pulse
outputs
on
RD
issue
PCBA
terminal
at:
No.
Version
TDCR
orNV
DS
(RD
output:
LOW
level)
A"'D
-00
A"-'C
OPEN
HL
During
write
operation
(
-04
A"-'C
(Internal
control
of
LSI)
-14,A,B
RDYO
HL
During
write
+
Drive
not-READY
(RDYO:LOW)
_.
E
-08,B,C
APS
H L
During
write
+
During
motor
start-
-lOA
ting
(36O'V380ms
after
MON)
+Head
-lSA
seek
operation
F'V
-OOD'\.
OPEN
HH
The
same
as
-0Qt\..04
of
PCB
issue
~
-040'\.
A"-'D.
-080'\.
RDYO
HH
The
same
as
-14
A"-'D
of
PCB
issue
-lOB"-'
A"-'D.
-14C'V
-ISH""
Special
RDYO
APS
H
During
write
+
Drive
not-READY
+
Head,
seek
operation.
(Table
302)
RD
output
control
of
read
write
LSI'
-312 -
Magnetization
on
disk
Pre-amp.output
(TP4)
Pre-amp.output
(TP5)
Differentiation
amp.output(TP7)
Differentiation
amp.
output
(TP8)
----l-~~-+--~:__----::;~---J't"-__t'---..;::".""r;::::.__-
2.
5V,
approx.
..L...--l-..:::::,.........--+--~::::..-----=::~---;f---'l~---::T'<::..---
2. 5V ,
approx.
2.5V,
approx.
--..l:..-----¥:----I---~r-----)'--_4:___--_t_
2.
5
V,
approx.
Peak
detector
output
in
us
I~-
L
(Fig.304)
Read
amplifier
and
peak
detector
waveforms
-313 -
Virtual
pulse
(drop~in)
I
Tnn
LJLJl
fL
I
-H--A"'F
models:
Ills,
approx.
,G
model:
O.S\.ls,approx.
UUU
LnJIJ
LJ
RD
output
(US-33)
READ
DATA
(Jl-30)
Read
data
latch
output
in
uS
Edge
detector
#2
output
in
uS
Peak
detector
output
in
US
Edge
detector
#1
output
in
uS
Delay
s.s.
Q
output
in
US
(Fig.30S)
Time
domain
filter
and
read
gate
waveforms
-314 -
This manual suits for next models
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