IBM 5160 with ALPS 360k floppy where head will not return to track 1

[dklawren]

I have an ALPS half-height floppy that came with my IBM 5160 XT that has a strange issue. I do not get any post errors and the system will boot to the hard disk. If I put a
360k floppy in and try to access A:, it will start to try and read the drive and then give the abort, retry, fail error. I have notices that when the drive initializes on boot up, the head will
move as it should but it does not quite go all the way back to the starting position. If I manually move the head back to start, then access A: it will work fine. I can even load the disk directory and run a program. But if it has to load enough data to move the head far down and then come back, it doesn't make it back to start again and will fail the next time I load something.
I have done the usual, clear the rails, put some silicone lube on the rails, etc. I have put a small amount of lube near the stepper motor rod and best I can tell it moves back and forth freely.
I thought maybe the sensor for the starting track was faulty but it doesn't seem like the head make it far enough back for that to matter. What would be the best course or troubleshooting an issue like this? Bad stepper motor or bad IC on PCB? Lost on this one.

 

[kc8eyt]

Tear that puppy down then clean and lube everything. I've had a few drives exhibit similar behaviors. Nine times out of ten a good thorough cleaning brings them right back to life. I've always used gun swabs and isopropyl alcohol to clean everything and then follow up with white lithium grease on all moving parts.

From postings I've seen Chuck is the expert on drives and recommends a different cleaner (PERC) which I am going to try. Read here:

https://www.vcfed.org/forum/forum/c...10943-cleaning-diskettes-alone-are-not-enough

Old grease is stubborn to remove. I usually have to clean the old grease off, then clean again because even though it looks like it's gone it isn't. I'm hoping PERC will help with this.

 

[modem7]

This certainly sounds like a head stepping problem.

I have an ALPS half-height floppy that came with my IBM 5160 XT that has a strange issue ...

Have you proven that the drive is the problem cause?
Other possibilities that I can think of are:
* Step pulse output of floppy controller is bad.
* Bad ribbon cable disrupting step pulses to drive.
* Is your floppy configuration terminated properly? See [here]. Correct terminator for the drive?

If two drives on the cable, try with only the ALPS drive connected.

 

[SomeGuy]

One other thing that might be worth checking is if it behaves better using a lower step rate. Dos 5.x and later default to higher step rates, so perhaps try it under DOS 2.x. (There are also little utilities that can be loaded to change step rate).

Although, I would think this drive should be compatible with normal step rates.

BTW, you can use ImageDisk in alignment mode to manually move the head around. That might help reveal some pattern if there is one.