Hi,
I have the exact same problem with my drive. Could you go into detail with the process you did. I would love to fix mine as its been bugging me for a long time. 😀
I couldn't get ImageDisk reading my drive as its mapped to D: (Seems to only allow A and B)
Cheers,

Hi robbo007,

Yes, apologies for not mentioning the work that I had to do first, which was making up a custom cable! 😀
You're right that IMD won't work with an external drive, so you need to get it connected to a regular floppy controller to be seen as drive A: or B:

Background:
Internally, the DB37 goes to a 34 pin floppy connector on an adapter to connect to the 40 pin edge connector of the drive itself. There are two types of these external drives - the one for the IBM XT 5160 had a power pigtail, whereas the one for the AT 5170 only has the DB37 connector, which carries power on pins 1 & 4.
Mine is actually for a 5170 so it lacks the power pigtail for the 5160. Some people modify the controller card but I didn't want to do that - fortunately I had a male-female DB37 extension cable which I modded to add a power connector. See here for an old Instagram post of mine. If yours is the same (ie for a 5170), +12V goes to pin 1 and +5V to pin 4 of the DB37, ground on pins 2&3.

There are two options for making up an adapter cable to connect it as a normal floppy drive:
1) As above the DB37 cable goes to a 34 pin floppy connector internally anyway... so you can make a suitable cable by taking a normal floppy cable, cutting some of the wires, and soldering in a power connector (this is what I did).
If you do it this way, make sure you connect it the right way around, because I'm sure that you don't want to send those voltages into your controller card instead of the drive. Also double check which pins carry voltage. I really can't remember if pins 1-4 of the DB37 connector map to pins 1-4 of the 34 pin connector... quite possibly not. So PLEASE check continuity first with a multimeter. 😀

2) The safer / better and more reusable option would probably be to make a floppy to DB37 female cable which you can connect to the DB37 of the external drive. It just means you'd need to get a DB37 F connector. Check out this page on minuszerodegrees under the data cable section. Basically you need to make something a bit like this example pic but using a DB37 female (noting that the gap would appear to be on the other side).... Then if your drive is from the 5170, also wire in a power connector (+12V to pin 1, +5V to pin 4, ground to 2&3)

So... a disclaimer re voltage for the first option... and for the second option a disclaimer of "I didn't try this but can't see why it wouldn't work" (and double check all the pinouts etc) 😀

Once you actually get it connected as drive A: or B:, then using IMD is reasonably straight forward, but give me a yell if you need any help. I'd just suggest not touching the track 0 position sensor unless you absolutely need to. IIRC the conical screw has a fine thread which makes adjustment easier (ie a large turn has a small effect... just make sure you don't unscrew it all the way). But really, once I discovered that little #@$! the rest was easy!

robbo007 wrote on 2021-04-09, 13:23:

Hi, I have the exact same problem with my drive. Could you go into detail with the process you did. I would love to fix mine as […]
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Hi,
I have the exact same problem with my drive. Could you go into detail with the process you did. I would love to fix mine as its been bugging me for a long time. 😀
I couldn't get ImageDisk reading my drive as its mapped to D: (Seems to only allow A and B)
Cheers,

IMD doesn't care about DOS drive letters whatsoever. Even though the choices in the menu are "A, B, C, D" what that really means is unit number 0, 1, 2, 3 on the selected controller. It uses the primary FDC by default but you can use a secondary FDC (located at port 370) by starting the program with the switch /S. If your controller has support for 4 physical drives (like the IBM FDC included with the PC and XT) you can start the program with the switch /4 to enable the menu choices of "C, D" which again, mean units 2 and 3. If you plug a unmodified 4865 into a unmodified IBM FDC card, it will be unit 2.

maxtherabbit wrote on 2021-04-11, 14:25:

If your controller has support for 4 physical drives (like the IBM FDC included with the PC and XT) you can start the program with the switch /4 to enable the menu choices of "C, D" which again, mean units 2 and 3.

Thanks for the info... when I first read your reply I was like... wow you've gotta be kidding me, that would have saved a bit of time! 🤦

But unfortunately I'm not able to get that to work, although I haven't tried using IMD on the 5160 itself.
I used my "test box" (socket 7 machine) to do the drive adjustment. I've got a 4 port FDC card with its own BIOS (FDA-4) and using that I can successfully access the drive using driver.sys /D:2 /F:2... however IMD doesn't seem to work with this controller card 🙁 The TESTFDC utiility that comes with IMD gives a "no interrupt" error.
I've tried using it as a secondary controller and primary (with onboard FDC disabled). Also tried different DMA/IRQ settings, but no luck.

InbetweenDays wrote on 2021-04-12, 06:31:

Thanks for the info... when I first read your reply I was like... wow you've gotta be kidding me, that would have saved a bit of […]
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maxtherabbit wrote on 2021-04-11, 14:25:

If your controller has support for 4 physical drives (like the IBM FDC included with the PC and XT) you can start the program with the switch /4 to enable the menu choices of "C, D" which again, mean units 2 and 3.

Thanks for the info... when I first read your reply I was like... wow you've gotta be kidding me, that would have saved a bit of time! 🤦

But unfortunately I'm not able to get that to work, although I haven't tried using IMD on the 5160 itself.
I used my "test box" (socket 7 machine) to do the drive adjustment. I've got a 4 port FDC card with its own BIOS (FDA-4) and using that I can successfully access the drive using driver.sys /D:2 /F:2... however IMD doesn't seem to work with this controller card 🙁 The TESTFDC utiility that comes with IMD gives a "no interrupt" error.
I've tried using it as a secondary controller and primary (with onboard FDC disabled). Also tried different DMA/IRQ settings, but no luck.

Many thanks guys. This is the only post about this problem I've found online, I've seen on other forums many people with this same problem. I have the XT model so its got the power cable and works perfectly with the /4 switch.

@InbetweenDays: Would you be able to help with, opening the drive (plastic is darn tight, not sure which way it opens. Don't want to force it) and also how to align successfully with IMD?
Thanks,

Sure, no problem... will post a pic soon.

4865 disassembly part 1:

A small clip can be seen through the rear vent slots on each side of the drive. Use a small screwdriver or similar to gently press one clip in, while using your other hand to pry the two halves apart (fingernails work, or you could use a pry tool). Then do the other side.

Remove the enclosure cover, then these two screws to remove the metal cover.

Now remove the screws from the adapter board. Unplug the 34 pin connector to be able to free the cable from the case, and then remove the board from the drive edge connector. (Note: I didn't unplug the 34 pin connector in these pics as you don't HAVE to in order to get the cable out, but it makes it easier and you will need to unplug it for reassembly later too).

Finally, remove the two screws holding the drive into the case and the cable shield wire. Remove the cable and drive from the enclosure.

4865 disassembly part 2:

This is how it looks with the drive removed.

Flip it over and remove these two screws holding the drive in the metal bracket.

Now you can plug the cable and adapter back in and proceed to using IMD to do the alignment. As per my original post, these are the two points of interest. The conical adjustment screw is marked, along with the solder point at which you can measure voltage when adjusting the track 0 sensor. (But I'd really advise leaving that alone unless you really need to adjust it)

Final note...
If you need to clean/lube the worm gear shaft or heads etc, you need to remove these screws (2 on each side) to remove the top plate. Then there are some wires to carefully unplug, and a couple more screws to remove the top circuit board. Sorry but I didn't go that far when taking these pics.

Alignment using IMD

It's actually pretty simple once you get to using IMD. I'd suggest checking out these two links that explain the process quite well - this is what I read first.

https://vswitchzero.com/2018/05/07/5-25-flopp … rive-alignment/ (and the old thread link too)
And from Dave Dunfield himself: https://comp.os.msdos.misc.narkive.com/UaZSEA … isk-drive#post5

You should be good to go after reading those, but let me know if you do need any more help. 👍

PS... I've also used ImageDisk on an old 5.25" drive that had an issue with the top and bottom heads being out of alignment with each other.
I have to say that it's really VERY satisfying when you successfully realign the heads, hear those high pitched beeps in IMD, and end up with a working drive. 😀

Proper head alignment is done with a special analog alignment disk and an oscilloscope. Aligning a drive using the IMD beeper is ghetto and should only be done as a last resort

InbetweenDays wrote on 2021-04-13, 12:54:

Alignment using IMD […]
Show full quote

Alignment using IMD

It's actually pretty simple once you get to using IMD. I'd suggest checking out these two links that explain the process quite well - this is what I read first.

https://vswitchzero.com/2018/05/07/5-25-flopp … rive-alignment/ (and the old thread link too)
And from Dave Dunfield himself: https://comp.os.msdos.misc.narkive.com/UaZSEA … isk-drive#post5

You should be good to go after reading those, but let me know if you do need any more help. 👍

Thats amazing. Thank-you so much. I'll try this weekend when I have more time and let you know how I get on 😀

robbo007 wrote on 2021-04-13, 14:43:

InbetweenDays wrote on 2021-04-13, 12:54:

Alignment using IMD […]
Show full quote

Alignment using IMD

It's actually pretty simple once you get to using IMD. I'd suggest checking out these two links that explain the process quite well - this is what I read first.

https://vswitchzero.com/2018/05/07/5-25-flopp … rive-alignment/ (and the old thread link too)
And from Dave Dunfield himself: https://comp.os.msdos.misc.narkive.com/UaZSEA … isk-drive#post5

You should be good to go after reading those, but let me know if you do need any more help. 👍

Thats amazing. Thank-you so much. I'll try this weekend when I have more time and let you know how I get on 😀

make sure you exhaust every other possible cause of your issues before messing around with the alignment, there is no going back once you deviate from the factory setting unless you buy a real alignment disk

maxtherabbit wrote on 2021-04-13, 15:51:

Alignment using IMD
make sure you exhaust every other possible cause of your issues before messing around with the alignment, there is no going back once you deviate from the factory setting unless you buy a real alignment disk

Can you still buy alignment disks for these drives? I don't have an oscilloscope so this is my only real option.

InbetweenDays wrote on 2021-04-13, 13:01:

PS... I've also used ImageDisk on an old 5.25" drive that had an issue with the top and bottom heads being out of alignment with each other.
I have to say that it's really VERY satisfying when you successfully realign the heads, hear those high pitched beeps in IMD, and end up with a working drive. 😀

Right I managed to find some time to open the drive and connect to IMG on the XT.

Dave Says:
"For alignment, it allows you to seek to any track on the disk,
and sits in a continuous read loop. It provides a running display
of the number of sectors read which match the seeked track
ID, and the number read which don't match. There is also an
audible "beep" which increases in pitch the more matching
sectors are found."

So to get my head around this. From my photo I'm on track 0. Which column are the matched and unmatched entries? I see the second column reading the sectors 1-9 but then displays them out of order? Sorry for the dumb questions but don't want to break my dive 😀

Right so further usage of ImageDisk I get the following using Single step:
T0 H0: x 18 0
T1 h0 to t67 h0: x 0 18
T68 H0: x 0 12
T69 H0: x 0 13
T70 H0: x 0 16
T71 H0: x 0 18
T72 H0: x 0 16
T73 H0: x 0 9
T74 H0: x 0 16
T75 H0: x 0 18
T76 H0: x 0 12
T77 H0: x 0 8
T78 H0: x 0 12
T78 H0: x 0 18
T80 H0: ?

Actually that first pic looks like a perfect read of track 0. The first column (with all the 0's) shows the track ID actually read from the disk. You can ignore the second column which is the sector being read. The third column is the number that matched the seeked track ID; the fourth is those that don't match.

So, excuse the rubbish pics but I just took these quickly as an example, using a 1.44MB drive.

Good read of track 0:

Then I manually moved the heads by slightly turning the worm gear, resulting in the head going back slightly (before track 0)... hence the ? as no track ID was read.

Moved the heads back the other way and it was then reading track 1... as far as IMD was concerned it was meant to be reading track 0 but wasn't, and hence no matching sectors.

Hope this makes sense.

You sure you're using single step? Your photo says double step

Anyway I'd guess more likely a problem with the stepper based on those results

Are you using a suitable 720k floppy that was formatted on a different drive known to be working properly? (I used an original software disk).