ittist
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NOTE
The flow charts are for information
only and for warranty purposes
any
faulty drive
mechanism must be
returned to
Amstrad
for
replacement. Service Agents should not
attempt
to
repair the
mechanism.
Service Agents should note
that the hard disc units are the
most sophisticated
mechanisms
and should
never be
opened in
a
normal
environment. If any attempts are made to
open the hard
disc unit the
guarantee is
then invalidated
and
Amstrad
takes no
responsibility
to
exchange the drive.
You should
note further that there
are two types
of hard disc
units in use
i.e.
Alps and
Tandon. When
ordering the
replacement units
make sure that the
Part
No.
is
either 175037
for the
Alps drive or 60001
for the
Tandon
drive. This
information applies
only
to
the 20MB drives.
Amstrad reserves the
right
to
ammend the circuit or
change the components
without
prior warning.
Use
RP4 diagnostics expansion
card or diagnostic disc for
fault findings.
FD3 MAINTENANCE
1. Introduction
This maintenance manual is
for the
maintanance
FD3
1-1
General
The floppy disk Drive is
a
high precision equipment and requires the following
Special
Jigs,
Tools, measuring
instruments and Adjustment when repairing or changing
parts.
2.
Special
Jigs,
Tools and Measuring Instruments
2-1
List of Special Jigs and Tools
CE diskette Dysan 224/2A
Blank diskette
Cleaning diskette
2-2
List of Measuring Instruments
Oscilloscope
Brian
Frequency
Counter
2-3
CE Diskette (Alignment Diskette)
This Diskette is used for the following adjustments and checks.
R/W head radial position
R/W
head azimuth
Index burst timing
3. Diagnosis Procedure
3-1
General
Hard
errors
are
often caused by an incorrect procedure erroneous
programing or damaged diskette, and soft
errors are often
caused
by dirty air or random electric noise. And other external factors are often considered to
be
drive failure or incorrect adjustment. Check that errors are repeatedly produced with the first diskette and
that
similar
errors are also produced with other diskettes,
unless obvious assembly trouble or 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 out by the liner in
the diskette.
2)
Random electrical noise less than several microseconds.
3)
Delicate track misalignment and writing
timing
misalignment, these are not
detected
during writing, and may
cause
soft errors during reading.
4)
Incorrect
ground
of the drive
or host system power supply.
5)
Incorrect spindle
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
recovered.
2)
Access the head
to
an adjacent track if the error is not recovered
by step
(1)
then return the head to the
previous track.
3)
Repeat step
(1).
4)
Recalibrate the head
then access
the previous track and repeat
step
(1).
5)
An error 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 the drive is responsible for the error. If the
same error
occurs on another track, change the diskette and repeat these steps. If
the error still occurs, the
drive has
some
fault.
If the error
does
not occur, the diskette is defective.
3-4
Read
Error
Most
errors
are soft errors.
Data
can
be
recovered
by
following the recovery steps
3-2.
3-5
Seek Error
If seek error occurs, recalibrate the head then
access
target track once more.
If
seek error occurs again, the drive has some faults.
Most
seek errors
are
caused by stepping motor trouble or stepping motor drive
circuit trouble.
3-6
Compatibility Error
In some cases, data written by one drive cannot
be
read
by
another drive.
This is
due to the
following
reasons:
The check points
are
listed
below.
1)
Incorrect 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.
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