Post by E***@yahoo.comI have a couple of old 5.25" drives which are having trouble reading
some archive 5.25" floppy disks (these disks read fine on other
equipment).
Is there any way to adjust/align these disk drives to try to get them
to work better?
To properly align a drive you need an alignment disk and a scope.
However - you usually get "close enough" without any special
tools if you are careful.
My ImageDisk, a program primarily for for archiving and restoring
"any format" floppy comunicates directly with the PC floppy controller
and has a couple of functions which may be useful to you. ImageDisk
is available at: http://www.classiccmp.org/dunfield/img/index.htm
(Note, you will need a DOS or Win9X PC to run ImageDisk).
#1 is a disk head cleaning cycle. To use this, you need a 5.25 "wet"
head cleaning disk. Wet the "media" (with alcohol) as per the
manufacturers directions, insert the disk and run the head cleaning
cycle - this will "scrub" the heads back and forth in a zig-zag pattern
to clean the heads.
If you don't have a head-cleaning disk, you may be able to clean
the heads with a Q-tip and some alcohol (use the solution from a
tape head cleaning kit). On some drives you can pull the heads
far enough apart to swab them with a Q-tip, and on others you
can't - don't force them. Best to find a cleaning disk if you are
unsure about doing this.
#2 is an Align/Test function. This will let you manually control
the drive, seek, read, format, write individual tracks etc.
For alignment, it allows you to seek to any track on the disk,
and sits in a continuous read loop. It provides a running display
of the number of sectors read which match the seeked track
ID, and the number read which don't match. There is also an
audible "beep" which increases in pitch the more matching
sectors are found.
How you physically adjust head alignment varies from one drive
to another. For some you loosen the stepper motor and rotate it.
For others, you loosen the whole head carrier assembly and there
is either a worm-screw or a slotted cam which moves it back and
forth.
To "best guess" align the drive, start with a diskette formatted
on a known good drive. Seek to various tracks, and adjust the
head position for the highest audible tones. Note the limits where
the tone starts to drop, and assume "dead center" between
those limits is the best alignment point for that track. Do this at
several tracks over the range of head movement and find
the best compromise for all positions. Confirm your results with
several other known good diskettes from other sources - find
the best compromise.
#3 is the track-zero detect switch. During the Align/Test function,
ImageDisk will show you the status of the track-0 sensor at the
top of the screen. Make sure that it comes on when you step to
track 0, and goes off when you step to track 1. If not, you
may have to adjust the sensor position.
Note that if you have either the alignment or track-0 sensor
wrong, you may not be able to adjust the other correctly. If the
drive is really bad to begin with, you may have to go back and
forth between the two a few tmes in order to get to the point where
you can make the correct adjustments.
usual caveats and disclaimers apply - if you don't know what you
are doing, you can really mess up your drive. Since you have
to run the drive "out of the box" to do this, you can also mess up
your PC. Don't blame me if you stab yourself with a screwdriver
etc. etc.
--
dave06a@ Collector of classic pre-PC computer systems.
dunfield. If you have an old 8/16 bit non-PC system in need of a good
com home, please contact me at email address on the left, or
via contact link of this web site:
http://www.classiccmp.org/dunfield/index.html