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Toshiba FDD6882-EIJ, 96 TPI but can only step to 40 tracks(?!)

Jackson

Jackson

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Has anyone seen this in the wild? It's an unusual specification. The jumpers match the FDD6881-H1R in the manual.
Could it be that a resistor is malfunctioning, or is it intended by design? Disk reads and writes appear to be working fine otherwise, if the SuperCard Pro gives me any indication.

It was set to DS1 when I got it, in contrast to how the FDD6881-H1R has DS2 set by default according to the manual.
This indicates that it was last used with a machine that had a Shugart-style pinout. Could this explain it?
 
Could you show a picture of the jumpers on the drive? I know that a few 96 tpi drives had a setting to force double stepping the drive making it into a 40 track drive with half width tracks.
 
There are actually a couple of other unknown jumpers that don't seem to match the list. For instance, there is a WP (write protect?) jumper:
SFkBkrk.jpeg


Do you know which one could possibly enable 80 track capabilities?
 
I was hoping that there would be a jumper that was set differently from the standard 80 track configuration. I don't see it.

Do you know the provenance of the drive? BBC Micro drives were the most common to have a switch making 80-track drives only use 40 tracks.

Have you examined the drive to make sure nothing is blocking head movement? Does the drive head move in a double stepping manner?
 
The drive has atypical plastic rails attached to the sides, meaning that it couldn't have been for a typical IBM PC computer. They look to be the slide in kind; no clips. I am from the US, so it was not a BBC Micro, I'm sure. I tried every jumper combination and it appears that none of them enable 80 tracks. Shucks.
 
Before my attempts to clean it, it left thin marks that were clearly 96 TPI. The flux streams show that it is clearly a 96 TPI drive.
The only thing to do at this point is swap the board with another one that uses the same mechanism and pinout.

This is what the rails look like, by the way. Can anyone identify what they would have been placed in?
MPix7Ps.jpeg
 
The rails look to be standard 5170/AT clone ones. I have a bucketload of those.

What you're saying is that the drive automatically double-steps?
 
That looks like the rails used in the AT clone I had. Memory is a tricky thing; it looks backward with the tiny notch being where the little clip at the front of the drive bay locks it in place.

What system is currently using it?
 
Ah. I don't have a 5170 in my collection, so I forgot the rails looked.
No, the drive does not double step. It single steps and jams after track 41 or so.

Looking at the head assembly, the motor/stepper seems to jam itself moving halfway.
it might need some lubrication; that might what be the problem.

EDIT: Definitely a lubrication issue. Waste of my time...
 
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