[Coco] Re: Drive speed incompatibilities

[Robert Gault]

Add whatever you want to the Basic program. My system always runs at width80 so
I did not include the command. As the program came from an article I wrote, it
is more a tutorial than a finished product.

If your drives measure 303 and 299 rpm, then there is no need to adjust them as
they are well within tolerance. It is possible that the drives won't permit
adjustment and use some type of phase-locked internal clocking. However, if you
want to check the 303 setting, you will need to find a mini 10 or 15 turn pot on
the drive circuit board that controls drive speed. Since there could be more
than one such, you are taking a risk of trashing your drive by turning the wrong
control.

It would be best to try to find a service manual or instructions at the
manufacturer's web site. Then you will know the location of the rpm adjustment
pot.

Keep in mind that if the tolerance for speed is +-1.5%, then your deviation of
1.3% could be twice as bad and might still work. I would leave this alone!

There may be some problem with magnetic density on the disks or track alignment
that is causing the problem. The latter is a very good possibility. Heads get
knocked out of alignment with respect to both track position and asimuth. If
that is the case, it would take a service shop to adjust the drive.

fsteeman at dds.nl wrote:
> 
> OK, thanks for that program RPM.BAS ! It was just what I was looking for and it
> works perfectly! OK, I have now determined that my new drive 0 is slightly off
> in speed from my old drive. In fact, my old drive 0 turns at almost 303 rpm
> whereas my new drive 0 has a speed of about 299. It is not much and just in
> between the 1.5% margin, but it would certainly explain why my new drive cannot
> read my old floppies.
> 
> The question now is: OK now I know that the drive speeds are different, what do
> I do next? Is it at all possible to adjust the drive speeds?
> 
> Cheers,
> 
> Fedor
> 
> PS: Not to criticize, but just one line that ought to be added to the RPM.BAS
> program would be: 5 WIDTH 80
> 
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