28 Jan
2010
28 Jan
'10
7:11 p.m.
Sometime ago I posted a request for help on my two Compaq Portable IIs that
failed to boot from the FDD.
I now can boot one using an "off the shelf" (at Weird Stuff) half height 360
kB FDD in place of either of the two Canon 5201 1/3 height FDDs that were in
the two Portable IIs. Both exhibit the same failure mode, while trying to
read the disk visibly spins erratically, as if there were some form of
stiction causing it to go slower and then faster. Manually turning it with
and without a disk, the spindle motor feels free of stiction.
It is surprising to me to find both Canon 1/3 height FDDs fail in the same
mode, suggesting a fundamental flaw in the design. For example, the full
height and half heights I used in this project are older than the Canon's,
of unknown provenance, but all 5 have worked flawlessly. Any ideas, other
than avoid old Canon 1/3 height FDs?
Anyone have a working 1/3 height 360 kB Canon FD? (I think I need Canon to
get the bezel right on the machine I am "restoring").
Tom
PS: I bought a package of 20 360 kB FDs off the internet and one of my
problems was that about 1/2 of them were full of defects, causing some of my
problems. I finally solved that problem by throwing away any disk with any
defect found during Format and doing a Diskcomp after each Diskcopy.
28 Jan
28 Jan
7:39 p.m.
--- On Thu, 1/28/10, Tom Gardner <thomas.gardner at sbcglobal.net> wrote:
Both exhibit the same failure
mode, while trying to
read the disk visibly spins erratically, as if there were
some form of
stiction causing it to go slower and then faster.
Manually turning it with
and without a disk, the spindle motor feels free of
stiction.
I had a standard half height floppy drive in a Compaq Portable 286 that did something
similar. I found that the glue holding the magnetic ring into the metal "puck"
on the motor had come loose. Removing the center screw (careful, it's left-hand
thread!) will allow you to take off the puck. Inside, there should be a magnetic ring
glued into place. In my case, that ring was loose, and dragging against the board. A
little super glue and it was good as new. Perhaps yours is crooked, but not dragging on
the baord yet?
Anyone have a working 1/3 height 360 kB Canon FD? (I
think I need Canon to
get the bezel right on the machine I am "restoring").
I had to replace a 1/3 height floppy drive in a friend's sequencer one time. It was a
720k (80 track, double density 5 1/4") drive, and there was something wrong with the
heads or read/write logic - it would appear to write disks, but could not read them back.
Mechanical motions were fine.
I ended up using a half height 1.2mb Teac drive that I hardwired to run as 720k. I had to
strip down the mechanism and cut the aluminum casting down with a dremel on the front so
it would match up with the 1/3 height opening in the front of the sequencer. The faceplate
was able to remain mostly unmodified, and it hung over the opening on the front of the
sequencer. All told it looked pretty good when I was done... however this probably
wouldn't work on your Compaq, I don't remember there being enough room on the side
of one of those things.
-Ian
9:47 p.m.
On 28 Jan 2010 at 11:39, Mr Ian Primus wrote:
I had to replace a 1/3 height floppy drive in a
friend's sequencer one
time. It was a 720k (80 track, double density 5 1/4") drive, and there
was something wrong with the heads or read/write logic - it would
appear to write disks, but could not read them back. Mechanical
motions were fine.
I ended up using a half height 1.2mb Teac drive that I hardwired to
run as 720k. I had to strip down the mechanism and cut the aluminum
casting down with a dremel on the front so it would match up with the
1/3 height opening in the front of the sequencer. The faceplate was
able to remain mostly unmodified, and it hung over the opening on the
front of the sequencer. All told it looked pretty good when I was
done... however this probably wouldn't work on your Compaq, I don't
remember there being enough room on the side of one of those things.
Could you have better used the 5.25' section from a Teac FD-505 dual
drive?
--Chuck
10:02 p.m.
Sometime ago I posted a request for help on my two Compaq Portable IIs that
failed to boot from the FDD.
I now can boot one using an "off the shelf" (at Weird Stuff) half height 360
kB FDD in place of either of the two Canon 5201 1/3 height FDDs that were in
the two Portable IIs. Both exhibit the same failure mode, while trying to
read the disk visibly spins erratically, as if there were some form of
stiction causing it to go slower and then faster. Manually turning it with
and without a disk, the spindle motor feels free of stiction.
It is surprising to me to find both Canon 1/3 height FDDs fail in the same
mode, suggesting a fundamental flaw in the design. For example, the full
Hve you checked -- with a voltmeter and 'scope -- the 12V power line to
the drives? It's possible the original Canon drives need more current
than your replacemetn (enve if they're working correctly) and you have a
PSU problem that is cuaseing the 12V line to dip under those conditions.
If it's certianly the drive (I'd stick it on an exerciser powered by a
known-stable PSU), I'd start ivestigatgn the spindle motor. I assume it's
a direct-drive mortor under the spindle (that's not _always_ the case,
even in slimline drives).. Strip it down and check the windigns for
open-scirucits. Check the outputs of the hall sensrs witha 'scope when
the motor is running. Maybe suspect the motor control IC((if you're lucky
it'll be a stnadard one.
-tony
5448
days inactive
5448
days old
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ard＠p850ug1.demon.co.uk -
cclist＠sydex.com -
ian_primus＠yahoo.com -
thomas.gardner＠sbcglobal.net