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romanon
March 17th, 2014, 06:56 AM
Hi, i have IBM full high 5.25" floppy drive on my 5150. First problem was immobile reading heads, they were stuck, but the DIR command worked, other reading action not.
So i cleaned, anointed and bestir stepper motor parts, everything looked fine, floppy drive sounded typical sound when booted (previously not) but cant read boot diskette. Command DIR not work anymore. Any help?

Chuck(G)
March 17th, 2014, 09:14 AM
Did you disturb the alignment?

romanon
March 17th, 2014, 11:39 AM
How would I know? :)

KC9UDX
March 17th, 2014, 12:11 PM
It sounds like the head was positioned to the directory track the last time it was used, at which point it seized in that position.

Since then, you tried using it, and so the motor was trying to move the stuck head. That in itself could have caused a misalignment.

If I were you, I'd disconnect the head stepper motor, and manually move the head until I could get the directory to read again. Then, mark that position somehow, reconnect the motor, and do a "DIR" command. You should be able to see how far it's off, and thus how far to adjust it.

Before you do anything though, clean the read head(s) with alcohol. You never know when the head could get too dirty to work.

MikeS
March 17th, 2014, 12:48 PM
Can you still boot the computer without it (i.e. is there another bootable drive) so you can use it to test the drive?

You'd think that after being anointed and bestirred it oughta work for sure... ;-)

Chuck(G)
March 17th, 2014, 02:17 PM
So i cleaned, anointed and bestir stepper motor parts, everything looked fine, floppy drive sounded typical sound when booted (previously not) but cant read boot diskette. Command DIR not work anymore. Any help?

As others have noted, it's entirely possible that you had dried-up lubricant or just dirt on the head carriage rails. But did you loosen any screws on the stepper mechanism, particularly ones holding the stepper in place? If so, there's your answer. Rotating the stepper in its mountings adjusts the head alignment and it's very sensitive.

romanon
March 18th, 2014, 12:27 AM
Ok, i tried to clean heads with alcohol, nothing changes...Next i disconnect stepper motor and tried to find possition to DIR command execution. When i moved heads to outer edge, i get message "General failture error reading drive B"
When i moved heads slightly onwards, i get message "Seek error reading drive B". Is this information is interesting for us?

KC9UDX
March 18th, 2014, 06:25 AM
"Seek error" suggests to me that it is reading the track, and determined it is on the wrong track. But, I don't remember much about IBM drives.

I'd try moving it to another track. Where, physically, is the directory track on an IBM disk? Where was the head positioned when the DIR command was working? Try positioning it there and see what happens. If you get a "Seek error," try positioning small amounts one way or the other, and see what it does.

Chuck(G)
March 18th, 2014, 08:37 AM
The message comes from the fact that the controller read an ID address header and the cylinder number contained in the header didn't match the cylinder number expected by positioning the drive.

In other words, the alignment is hosed and needs to be adjusted.