TI 99/4a Disk drive problems.
Saar Maoz
I have just reconfigured the TI computer that was sitting for a long time in
my room, I have an expansion box with extra memory and a 5 1/4" floppy drive.
I was able to read and run all my programs that I had saved onto floppies
back in 1983, however when I tried saving something to any floppy it returned
an I/O error 06 and after that I was not able to even read from that floppy.
I ruined 3 this way, until I realized that the drive may be faulty.
Any attempt to format some floppies returned I/O errors 21 or 31, I checked
the write protect and it looks like it's working fine.
So I took the disk drive apart and found an old disk label in it, after
removing it I still see the same behaviour.
I wanted help from as many people as possible, in ideas or thoughts as to what
to do.
1. How come I can read just fine, but can't write at all?
2. How can I clean the write heads? if any...
any other ideas would be appreciated.
Thanks, Saar
email: sm...@us.oracle.com
Phone: 415-506-5473
eic...@delphi.com
>1. How come I can read just fine, but can't write at all?
>2. How can I clean the write heads? if any...
connectors, includeing the edge on the side of the console and any
cartridges that you may be using.
You can probably pick up 5.25" DS/DD half height for around 25 dollars.
That would be the best way to go. If I remember correctly, one of
those error messages you got, is one that will appear if you put the
floppy disk in reversed.
You can also run into other strange problems if you are using DS disk in
a single sided drive.
Two half height drive can be easily moundted in the pbox. I would probably
try to get Teac drives if you can....
Dano
Gary D Bishop
In article: <40bm9f$l...@inet-nntp-gw-1.us.oracle.com>
Saar Maoz <smaoz> writes:
>I wanted help from as many people as possible, in ideas or thoughts as to what
>to do.
>1. How come I can read just fine, but can't write at all?
>2. How can I clean the write heads? if any...
Saar: As long as all you tried to to was read, there was no need to
use any of the write circuitry on the drive. Things behaved normally.
If there was a problem in the write circuitry, and you attempted to write,
things got messed up. In a normal write operation, the file table on the
disk is read into memory, modifications to it are made for the file you wish
to write, then the file table is written back to the disk. If all went
well, then the actual file contents are written to the disk.
Once the failed attempt to write the file table back to the disk has
occurred, the entire file table is now unreadable. The disk now
looks like it has a lot of errors, or even may report back that it is
uninitialized. Take heart, though. There are disk fixing tools out
there that can recover your files off the blown disks.
I also had a drive behave as you describe. There was a fault in
the write circuits that simply erased everything. Technically, an gate output
got stuck and didn't apply an alternating field to the disk during write.
It just applied DC. This made a very effective erasure. I too blew a few
disks before I figured out what was going wrong.
The read head is the same as the write head. There are separate
sections on the head for each operation, but physically they are
the same head(s).
Disk cleaners are available for cleaning heads. They look kind of like
a regular disk, but instead of a magnetic disk there is a porous media
to which you apply a cleaning fluid. Insert it into the disk drive,
ask some disk manager to attempt to format the drive a few times, and that
should do it for normal levels of crud. If there is any sticky on the head
left from the disk label, stronger measures and chemicals are called for.
Depending upon your level of expertise, you may want to attempt this
yourself. It involves locating an appropriate cleaner, such as
chlorothane or some other solvent. Don't let any of the cleaner touch
any plastic, or damage may occur. For that matter, minimize your own contact
with the cleaner and its vapors. You need to disassemble the disk drive
far enough to gain acces to the head(s). Use a lint-free applicator,
it resembles a Q-tip, but with a foam or spongy end to it.
The circuit board usually needs to be removed or loosened from the drive.
You may only have to disconnect a few wires to move the board out of the
way. Observe and/or mark the connections and their orientation, if you
don't recogize how to reassemble it.
You need to carefully insert the applicator (with chemical applied) between
the heads, and lightly wash the heads. This involves slightly lifting the
top head. Be gentle, and also don't lift any higher than necessary to insert
the cleaner. Take your time; don't try to remove all the crud at once. I find it is best to concentrate
on just one head at a time, either the top or the bottom. You must
be very careful not to push too hard, or apply sideways forces. This can
bend the mounting arm, or destroy the head alignment. A small mirror
is very handy to observe the surface of the top head, which is pointing down.
While you are in here, you should consider degaussing the heads. I use
a wand made for demagnitizing cassette player heads. It has a small metal rod
with a protective rubber tip. It is ideal to reach in small places, like
the gap between the heads.
If your drive is single sided, you will have only one head on the bottom to
clean. The top is a small felt pad. As long as there is some amount of
pad protruding from its holder, you do not normally need to do anything to
the pad. If the pad has been fouled with computer label sticky, you will
need to replace the pad. It is called a head load button. These are not
generally available, but could be salvaged from another drive that
expired for some other reason.
Hope this helps. -Gary
My email address is gdbi...@crems.rockwell.com, regardless of what the
header of this message states.