AMSTRAD PPC 512S - Page 3

FD-5
MAINTENANCE
AND
ALIGNMENT INFORMATION
(FOR
INFORMATION
PURPOSES ONLY)
v
1.
OUTLINE
OF
MAINTENANCE
•
The
following
tools
are
required for
maintenance
of
a
Floppy
Disk Drive
1.1
Alignment
Diskettes
Alignment
diskette
is
used for
head
actuator alignment
and index
sensor alignment.
Use the
JU-01AA
-
DD and
817-363CE.
1.2 Exerciser
The
exerciser
enables
you
to make all
adjustments
and inspections
necessary for
an FDD. Its functions
include
the
following:
(1)
Seek increment
or
alternate
tracks
(2)
Read
(but no
data
compare)
(3)
Write
1
F
or 2F
(All
O's or
1
's)
(4)
Recalibration
to track
00
The
exerciser
has
switches
and indicators
to execute
a specified function.
2.
DIAGNOSTIC
PROCEDURES
2.1
Error
Symptom
Recognition
Errors
that
occur because
of the wrong
operating
procedure,
wrong programming,
or
use
of
a defective
diskette, or soft
errors
due to external
causes, such
as contaminated
air and random
electrical noise,
are often
attributed
to a drive failure.
Unless
a visual
inspection
of the drive
reveals an evident
assembly
fault or
a
defect,
always
confirm errors
with another
good diskette,
and another
known
good
drive.
2.2 Soft Error
Detection
and
Correction
Soft errors
are normally
caused
by the following:
(1)
Contamination
between
read/write heads
and diskette.
This kind of
contamination
can
be
easily
eliminated
by the liner
in
the
diskette.
Contaminated
heads can
be cleaned
by a general purpose
non-abrasive
head cleaning
diskette. Please
follow
the
suitable
procedure
provided with
the cleaning
diskette.
(2)
Random
electrical
noise, normally
a
few
microseconds
or less.
(3)
Small
defects in
written
data and/or track
not detected
during write
operation
may
cause soft errors during
read.
(4)
Faulty
grounding
of the
drive or host
system can
also
cause a soft error.
(5)
Wrong motor
speed is
another
cause of soft errors.
Take
the following
steps on
the controller
side to recover
from the soft
errors
mentioned above.
(1)
Read
the
track
again
ten times or
until the
data is recovered.
(2)
If
Step
(1)
above fails
to recover
the data,
access the
adjacent track. Then
return the
head
to
the
original track.
(3)
Repeat Step
(1).
(4)
Any error that
cannot
be corrected
by
the
above
procedure is
irrecoverable.
2.3 Write Error
If
an error
occurs during
write operation,
it is usually
detected during
the next
revolution
by performing
a read
operation
called
write
check. To correct
an error,
write again
and repeat
a
write
check
operation. If
the result is
unsatisfactory
after ten
or more
write
operations, perform
a
read
operation
on another track
to determine
whether
it is the diskette
or the
drive that
is wrong.
If
an error persists,
replace
the diskette
and repeat the
above
procedure. If the
error still persists,
consider
the drive
defective.
If
the error is
corrected,
dispose of the
diskette
as defective.
2.4 Read
Error
Most read
errors are
soft errors.
Data
can be recovered
by following
the recovery
procedure
mentioned
in 2.2.
2.5
Seek Error
(1)
Stepper motor
or
stepper motor
circuit drive is faulty.
(2)
Faulty
Carriage
There are
two ways
of seek
error recovery.
One is
to
recalibrate
to track
00,
and
seek back
to the original
track. The
other is
to
read
the ID
field, check
the track
number
on which the head
is located,
and move
the head
away from
it. And
read it
again.
2.6
Interchangeability
Error
Data which
is written
by one
drive may not
be read
by
another.
This error
is called
an Interchangeability
error, which
can
be
caused mostly
by
the
following
reason, which
should
be
checked
as
follows.
(1)
Head
misalignment:
Refer
to Adjustments
and Confirmation
Item 5.5
(2)
Head
output
too low: Refer
to Adjustments
and Confirmation
Item
5.3
(3)
Motor
speed difference:
Refer
to Adjustments
and Confirmation
Item 5.1
(4)
Format
difference