Re: [M100] DVI Disk Formatting

[Brian K. White]

On 3/15/19 9:09 PM, George Rimakis wrote:

Hi all,

Sorry to bombard the list with DVI related posts, but I am having an issue.

So, I have two DVI’s one with two drives, one with one.

At first I used the DVI with one drive, was able to format the boot disk, and 
make a copy. After that I am not able to format any additional disks. I just 
get a Format Failed error.

I tried the second DVI, and only one of the two drives can format the disks. 
They all can read and write to disks that are formatted however.

I took them apart and cleaned the heads with isopropyl, but nothing has changed.

Does any have experience with 180k drives like this being unable to format, but 
otherwise appearing fine?

~George


First just make sure you are using SD or DD disks (360K) not HD (1.2M).

Other than that there are many age related failure points on all old 
floppy drives.


Make sure all the mechanicals are good obviously.

The rpm adjustment is easy, as there is a strobe sticker on the main 
spindle and a trim pot on the spindle motor driver board (there is also 
a trim pot on the main board, don't tough that one)

https://photos.app.goo.gl/jbBSq96GExzKCw727
https://photos.app.goo.gl/Ww6o6fXGzDfuTAcP9

For radial alignment, if you have an old 386-486 era machine (so it has 
a floppy controller that's old enough) you can try this method using 
ImageDisk:

https://www.classic-computers.org.nz/blog/2010-06-28-alignment-tandon-m100.htm
Note this method relies on having a disk that you believe has proper 
alignment to start with, to use as a reference. It can't be one you 
formatted in the drive previously, or in any other old questionable 
drive. Ideally it should be a few different commercially produced disks 
that previous owners probably never re-formatted.


That's about all the low hanging fruit other than you could try 
replacing the electrolytic caps and just visually inspect traces.. 
Beyond that you need to know how to actually diagnose electronics to 
find components that have gone bad.


Now here's a question for the group...
Drives had to have the radial alignment calibrated very exactly at the 
factory using special alignment disks, and then locked down for all time 
right?


I wonder if the plastic sheets that all disks are made of have shrunk at 
all over 30-40 years, making the *disks* out of alignment, causing 
people to take technically proper drives and move them actually out of 
the proper spec, so that they can read 40 year old disks??


(Or more specifically, 40 year old formatting. Even if the mylar sheet 
has shrunk, it would still format to spec again just fine, by just 
formatting it today in a properly aligned drive.)


If this idea is true, then I guess everyone should try to keep one 
out-of-spec drive just for reading old disks that you don't want to 
reformat. You don't ever format or even write anything with that drive, 
it's just for reading and just for really old disks. Then for formatting 
and writing you use a properly aligned drive.


And, if this idea of the mylar shrinking is true, does that mean that 
even if you had one of the original special factory calibration 
reference discs, that probably means that disk is no longer a good 
reference. It would be shrunk out of spec too. We'd have to come up with 
a new reference.


--
bkw

Re: [M100] DVI Disk Formatting

[John R. Hogerhuis]

I remember my full height Coco floppy drives required not just cleaning but
people would also do some timing or alignment them.  I don't think I went
through the process but they were capable of being calibrated I some way.
You'd think that would more affect writing on one drive and reading on
another but I don't know. Not calibrated could make write once read never
data.

I don't know if that drive is the same or if it uses a belt that might need
replaced.

Just guesses. I think people just replace those 1/2 height floppy drives in
the dvi when they act up.

On Fri, Mar 15, 2019, 6:23 PM Randall Kindig 
wrote:

> Funny you should ask.  At Tandy Assembly (http://www.tandyassembly.com)
> last year I found the same issue with my single-drive DVI.  I can boot from
> a disk fine, but cannot format.  It just crunches forever when trying to
> format, then eventually fails.  I didn’t try writing to a disk.  A second
> DVI I had (but sold at the show) worked fine.
>
> I’d love to know how to deal with that too.
>
> Randy
>
> On Mar 15, 2019, at 9:09 PM, George Rimakis  wrote:
>
> Hi all,
>
> Sorry to bombard the list with DVI related posts, but I am having an issue.
>
> So, I have two DVI’s one with two drives, one with one.
>
> At first I used the DVI with one drive, was able to format the boot disk,
> and make a copy. After that I am not able to format any additional disks. I
> just get a Format Failed error.
>
> I tried the second DVI, and only one of the two drives can format the
> disks. They all can read and write to disks that are formatted however.
>
> I took them apart and cleaned the heads with isopropyl, but nothing has
> changed.
>
> Does any have experience with 180k drives like this being unable to
> format, but otherwise appearing fine?
>
> ~George
>
>
>

Re: [M100] DVI Disk Formatting

[Gregory McGill]

likely old caps in the drive or controller needing replacement

On Fri, Mar 15, 2019 at 6:23 PM Randall Kindig 
wrote:

> Funny you should ask.  At Tandy Assembly (http://www.tandyassembly.com)
> last year I found the same issue with my single-drive DVI.  I can boot from
> a disk fine, but cannot format.  It just crunches forever when trying to
> format, then eventually fails.  I didn’t try writing to a disk.  A second
> DVI I had (but sold at the show) worked fine.
>
> I’d love to know how to deal with that too.
>
> Randy
>
> On Mar 15, 2019, at 9:09 PM, George Rimakis  wrote:
>
> Hi all,
>
> Sorry to bombard the list with DVI related posts, but I am having an issue.
>
> So, I have two DVI’s one with two drives, one with one.
>
> At first I used the DVI with one drive, was able to format the boot disk,
> and make a copy. After that I am not able to format any additional disks. I
> just get a Format Failed error.
>
> I tried the second DVI, and only one of the two drives can format the
> disks. They all can read and write to disks that are formatted however.
>
> I took them apart and cleaned the heads with isopropyl, but nothing has
> changed.
>
> Does any have experience with 180k drives like this being unable to
> format, but otherwise appearing fine?
>
> ~George
>
>
>

Re: [M100] DVI Disk Formatting

[Randall Kindig]

Funny you should ask.  At Tandy Assembly (http://www.tandyassembly.com 
) last year I found the same issue with my 
single-drive DVI.  I can boot from a disk fine, but cannot format.  It just 
crunches forever when trying to format, then eventually fails.  I didn’t try 
writing to a disk.  A second DVI I had (but sold at the show) worked fine.

I’d love to know how to deal with that too.

Randy
> On Mar 15, 2019, at 9:09 PM, George Rimakis  wrote:
> 
> Hi all,
> 
> Sorry to bombard the list with DVI related posts, but I am having an issue.
> 
> So, I have two DVI’s one with two drives, one with one.
> 
> At first I used the DVI with one drive, was able to format the boot disk, and 
> make a copy. After that I am not able to format any additional disks. I just 
> get a Format Failed error.
> 
> I tried the second DVI, and only one of the two drives can format the disks. 
> They all can read and write to disks that are formatted however.
> 
> I took them apart and cleaned the heads with isopropyl, but nothing has 
> changed.
> 
> Does any have experience with 180k drives like this being unable to format, 
> but otherwise appearing fine?
> 
> ~George

[M100] DVI Disk Formatting

[George Rimakis]

Hi all,

Sorry to bombard the list with DVI related posts, but I am having an issue.

So, I have two DVI’s one with two drives, one with one.

At first I used the DVI with one drive, was able to format the boot disk, and 
make a copy. After that I am not able to format any additional disks. I just 
get a Format Failed error.

I tried the second DVI, and only one of the two drives can format the disks. 
They all can read and write to disks that are formatted however.

I took them apart and cleaned the heads with isopropyl, but nothing has changed.

Does any have experience with 180k drives like this being unable to format, but 
otherwise appearing fine?

~George