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3.
Diagnosis Procedure
3-1
General
Errors
caused
by
an
incorrect
operating procedure,
erroneous programming,
damaged
diskette,
and
sott
errors
caused
by
dirty
air,
random
electric noise,
and
other external
factors are often
considered
to
be
drive failures or incorrect
adjustments.
Check
that errors
are
repetitively
produced
with
the
first
diskette
and
that similar errors
are also
produced
with other diskettes,
unless obvious
assembly
trouble
and
damage
are
found
in
visual
inspection.
3-2
Soft Error
Detection
and
Correction
Soft errors are
generally
caused
by the
following.
(1)
Dirty
air
between
the
R/W
head and
disk.
Normally,
this
dirt
is
cleaned by
the
liner
in
the
diskette.
(2)
Random
electrical
noise
less
than
several
microseconds.
(3)
Delicate track
misalignment
and
writing
timing
misalignment
that
are not
detected
during
writing
may
cause
soft
errors
during
reading.
(4)
Improper ground
of
the
drive or
host
system power
supply.
(5)
Improper motor speed.
The
following actions are required
on
the control side
to
recover the foregoing
soft errors.
(1)
Reread
the track ten
times
or
until
data
recovers.
(2)
Access
the
head
to
an adjacent
track
in
the
same
direction
as the
track
if
the
error
is
not
recovered by Step
1.
Then
return
the
head
to
the previous
track.
(3)
Repeat Step
1.
(4)
Errors
that
cannot be recovered
after
taking
these steps cannot be
recovered.
3-3
Write
Error
Operate
READ-AFTER-WRITE
if
an
error
occurs
during the
write operation.
If
the
error
cannot be recovered
after
operating
READ-AFTER-WRITE
more
than
four times,
operate
READ-AFTER-WRITE
on another
track
to
determine whether
the diskette
or drive
is
responsible
for
the
error.
Change
the diskette
and
repeat these steps
if
the
same
error
remains.
If
the
error
still
remains, the
drive
has
some
fault
and
if
the
error
is
erased, the diskette
is
defective
and
should be
discarded.
3-4
Read
Error
Most
errors are
soft errors.
Data can be recovered
by
following the error
recovery steps
(3-2).
3-5
Seek
Error
(1)
Trouble
with the
stepping
motor
or
stepping
motor
drive
circuit.
(2)
Carriage
trouble.
Seek
error
is
recovered by system
soft.
There
are
two
recovering ways.
(1)
Recalibrate
(2)
Detect
ID
field
3-6
Compatibility Error
In
some
cases, data
written
by
one
drive
cannot be
read by another
drive.
This
is
dur mainly
to
the
following
reasons:
The check
points are
listed
below.
(1)
Improper
head
alignment
—
5-2
(2)
The head
output
is
low
—
5-6
(3)
Motor speed
irregularity
—
5-1
(4)
Check
if
the
recommended
sector format
is
set
up.
3-7
List of
Test Points (see
figure 3-7)
Test Point
Signal
Name
TP1
AMP OUT
+
TP2
AMP OUT-
TP3
GND
TP4
STEP
TP5
READ DATA
TP6
INDEX
TP7
WRITE
PROTECT
TP8
TRACK
TP9
GND
3
Fig.
3-7 Test Point
Layout
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